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The Fauna of British India, Including Ceylon and Burma.
Published Under the Authority of the Secretary of
State for India in Council.
Edited by A. E. Shipley, M.A., Sc.D., HON. D.Sc., F.R.S.
FRESHWATER SPONGES, HYDROIDS & POLYZOA.
by
N. ANNANDALE, D.SC.,
Superintendent and Trustee (_Ex Officio_) of the Indian Museum,
Fellow of the Asiatic Society of Bengal and of the Calcutta University.
London:
Taylor and Francis, Red Lion Court, Fleet Street.
Calcutta:
Thacker, Spink, & Co.
Bombay:
Thacker & Co., Limited.
Berlin:
R. Friedländer & Sohn, 11 Carlstrasse.
August, 1911.
Printed at Today & Tomorrow's Printers & Publishers, Faridabad
CONTENTS.
Page
EDITOR'S PREFACE v
SYSTEMATIC INDEX vii
GENERAL INTRODUCTION 1
Biological Peculiarities 2
Geographical Distribution 5
Geographical List 7
Special Localities 13
Nomenclature and Terminology 17
Material 20
INTRODUCTION TO PART I. (_Spongillidæ_) 27
The Phylum Porifera 27
General Structure 29
Skeleton and Spicules 33
Colour and Odour 35
External Form and Consistency 37
Variation 39
Nutrition 41
Reproduction 41
Development 45
Habitat 47
Animals and Plants commonly associated with Freshwater Sponges 49
Freshwater Sponges in relation to Man 50
Indian Spongillidæ compared with those of other Countries 51
Fossil Spongillidæ 52
Oriental Spongillidæ not yet found in India 52
History of the Study of Freshwater Sponges 54
Literature 55
GLOSSARY OF TECHNICAL TERMS USED IN PART I. 61
SYSTEMATIC LIST OF THE INDIAN SPONGILLIDÆ 63
INTRODUCTION TO PART II. (_Hydrida_) 129
The Phylum Coelenterata and the Class Hydrozoa 129
Structure of Hydra 130
Capture and Ingestion of Prey: Digestion 133
Colour 134
Behaviour 135
Reproduction 136
Development of the Egg 139
Enemies 139
Coelenterates of Brackish Water 139
Freshwater Coelenterates other than Hydra 141
History of the Study of Hydra 142
Bibliography of Hydra 143
GLOSSARY OF TECHNICAL TERMS USED IN PART II. 145
LIST OF THE INDIAN HYDRIDA 146
INTRODUCTION TO PART III. (_Ctenostomata_ and _Phylactolæmata_) 163
Status and Structure of the Polyzoa 163
Capture and Digestion of Food: Elimination of Waste Products 166
Reproduction: Budding 168
Development 170
Movements 172
Distribution of the Freshwater Polyzoa 173
Polyzoa of Brackish Water 174
History of the Study of Freshwater Polyzoa 177
Bibliography of the Freshwater Polyzoa 178
GLOSSARY OF TECHNICAL TERMS USED IN PART III. 181
SYNOPSIS OF THE CLASSIFICATION OF THE POLYZOA 183
SYNOPSIS OF THE SUBCLASSES, ORDERS, AND SUBORDERS 183
SYNOPSIS OF THE LEADING CHARACTERS OF THE DIVISIONS OF
THE SUBORDER CTENOSTOMATA 185
SYSTEMATIC LIST OF THE INDIAN FRESHWATER POLYZOA 187
APPENDIX TO THE VOLUME 239
Hints on the Preparation of Specimens 239
ADDENDA 242
Part I. 242
Part II. 245
Part III. 245
ALPHABETICAL INDEX 249
EXPLANATION OF PLATES.
EDITOR'S PREFACE.
Dr. N. Annandale's volume on the Freshwater SPONGES, POLYZOA, and
HYDRIDA contains an account of three of the chief groups of freshwater
organisms. Although he deals mainly with Indian forms the book contains
an unusually full account of the life-history and bionomics of
freshwater Sponges, Polyzoa, and Hydrozoa.
I have to thank Dr. Annandale for the great care he has taken in the
preparation of his manuscript for the press, and also the Trustees of
the Indian Museum, Calcutta, for their kindness in placing material at
the disposal of the Author.
A. E. SHIPLEY.
Christ's College, Cambridge,
March 1911.
SYSTEMATIC INDEX.
Page
PORIFERA.
Order HALICHONDRINA 65
Fam. 1. SPONGILLIDÆ 65
1. Spongilla, _Lamarck_ 67
1A. Euspongilla, _Vejdovsky_ 69
1. lacustris, _auct._ 69
1_a_. reticulata, _Annandale_ 71, 241
2. proliferens, _Annandale_ 72
3. alba, _Carter_ 76
3_a_. cerebellata, _Bowerbank_ 76
3_b_. bengalensis, _Annandale_ 77
4. cinerea, _Carter_ 79, 241
5. travancorica, _Annandale_ 81
6. hemephydatia, _Annandale_ 82
7. crateriformis (_Potts_) 83
1B. Eunapius, _J. E. Gray_ 86
8. carteri, _Carter_ 87, 241
8_a_. mollis, _Annandale_ 88
8_b_. cava, _Annandale_ 88
9. fragilis, _Leidy_ 95
9_a_. calcuttana, _Annandale_ 96
9_b_. decipiens, _Weber_ 97
10. gemina, _Annandale _ 97
11. crassissima, _Annandale_ 98
11_a_. crassior, _Annandale_ 98
1C. Stratospongilla, _Annandale_ 100
12. indica, _Annandale_ 100
13. bombayensis, _Carter_ 102, 241
13_a_. pneumatica, _Annandale_ 241
14. ultima, _Annandale_ 104
2. Pectispongilla, _Annandale_ 106
15. aurea, _Annandale_ 106
15 _a_. subspinosa, _Annandale_ 107
3. Ephydatia, _Lamouroux_ 108
16. meyeni (_Carter_) 108
fluviatilis, _auct._ 242
4. Dosilia, _Gray_ 110
17. plumosa (_Carter_) 111
5. Trochospongilla, _Vejdovsky_ 113
18. latouchiana, _Annandale_ 115
19. phillottiana, _Annandale_ 117
20. pennsylvanica (_Potts_) 118
6. Tubella, _Carter_ 120
21. vesparioides, _Annandale_ 120
7. Corvospongilla, _Annandale_ 122
22. burmanica (_Kirkpatrick_) 123
caunteri, _Annandale_ 243
23. lapidosa (_Annandale_) 124
HYDROZOA.
Order ELEUTHEROBLASTEA 147
Fam. 1. HYDRIDÆ 147
1. Hydra, _Linné_ 147
24. vulgaris, _Pallas_ 148
25. oligactis, _Pallas_ 158, 245
POLYZOA.
Order CTENOSTOMATA 189
Div. 1. Vesicularina 189
Fam. 1. VESICULARIDÆ 189
1. Bowerbankia, _Farre_ 189
caudata, _Hincks_ 189
bengalensis, _Annandale_ 189
Div. 2. Paludicellina 190
Fam. 1. PALUDICELLIDÆ 191
1. Paludicella, _Gervais_ 192
2. Victorella, _Kent_ 194
26. bengalensis, _Annandale_ 195
Fam. 2. HISLOPIIDÆ 199
1. Hislopia, _Carter_ 199
27. lacustris, _Carter_ 202
27 _a_. moniliformis, _Annandale_ 204
Order PHYLACTOLÆMATA 206
Div. 1. Plumatellina 206
Fam. 1. FREDERICELLIDÆ 208
1. Fredericella, _Gervais_ 208
28. indica, _Annandale_ 210, 245
Fam. 2. PLUMATELLIDÆ 211
Subfam. A. _Plumatellinæ_ 212
1. Plumatella, _Lamarck_ 212
29. fruticosa, _Allman_ 217
30. emarginata, _Allman_ 220, 245
31. javanica, _Kraepelin_ 221
32. diffusa, _Leidy_ 223, 245
33. allmani, _Hancock_ 224, 246
34. tanganyikæ, _Rousselet_ 225, 246
35. punctata, _Hancock_ 227
2. Stolella, _Annandale_ 229
36. indica, _Annandale_ 229
himalayana, _Annandale_ 246
Subfam. B. _Lophopinæ_ 231
1. Lophopodella, _Rousselet_ 231
37. carteri (_Hyatt_) 232
37 _a_. himalayana (_Annandale_) 233
2. Pectinatella, _Leidy_ 235
38. burmanica, _Annandale_ 235
GENERAL INTRODUCTION TO THE VOLUME.
Although some zoologists have recently revived the old belief that the
sponges and the coelenterates are closely allied, no one in recent times
has suggested that there is any morphological relationship between
either of these groups and the polyzoa. Personally I do not think that
any one of the three groups is allied to any other so far as anatomy is
concerned; but for biological reasons it is convenient to describe the
freshwater representatives of the three groups in one volume of the
"Fauna."
Indeed, I originally proposed to the Editor that this volume should
include an account not only of the freshwater species, but of all those
that have been found in stagnant water of any kind. It is often
difficult to draw a line between the fauna of brackish ponds and marshes
and that of pure fresh water or that of the sea, and this is
particularly the case as regards the estuarine tracts of India and
Burma.
Pelseneer[A] has expressed the opinion that the Black Sea and the
South-east of Asia are the two districts in the world most favourable
for the study of the origin of a freshwater fauna from a marine one. The
transition in particular from the Bay of Bengal, which is much less salt
than most seas, to the lower reaches of the Ganges or the Brahmaputra is
peculiarly easy, and we find many molluscs and other animals of marine
origin in the waters of these rivers far above tidal influence.
Conditions are unfavourable in the rivers themselves for the development
and multiplication of organisms of many groups, chiefly because of the
enormous amount of silt held in suspension in the water and constantly
being deposited on the bottom, and a much richer fauna exists in ponds
and lakes in the neighbourhood of the rivers and estuaries than in
running water. I have only found three species of polyzoa and three of
sponges in running water in India, and of these six species, five have
also been found in ponds or lakes. I have, on the other hand, found
three coelenterates in an estuary, and all three species are essentially
marine forms, but two have established themselves in ponds of brackish
water, one (the sea-anemone _Sagartia schilleriana_) undergoing in so
doing modifications of a very peculiar and interesting nature. It is not
uncommon for animals that have established themselves in pools of
brackish water to be found occasionally in ponds of fresh water; but I
have not been able to discover a single instance of an estuarine species
that is found in the latter and not in the former.
[Footnote A: "L'origine des animaux d'eau douce," Bull. de
l'Acad. roy. de Belgique (Classe des Sciences), No. 12,
1905, p. 724.]
For these reasons I intended, as I have said, to include in this volume
descriptions of all the coelenterates and polyzoa known to occur in
pools of brackish water in the estuary of the Ganges and elsewhere in
India, but as my manuscript grew I began to realize that this would be
impossible without including also an amount of general introductory
matter not justified either by the scope of the volume or by special
knowledge on the part of its author. I have, however, given in the
introduction to each part a list of the species found in stagnant
brackish water with a few notes and references to descriptions.
BIOLOGICAL PECULIARITIES OF THE SPONGES, COELENTERATES, AND POLYZOA OF
FRESH WATER.
There is often an external resemblance between the representatives of
the sponges, coelenterates, and polyzoa that causes them to be classed
together in popular phraseology as "zoophytes"; and this resemblance is
not merely a superficial one, for it is based on a similarity in habits
as well as of habitat, and is correlated with biological phenomena that
lie deeper than what are ordinarily called habits. These phenomena are
of peculiar interest with regard to difficult questions of nutrition and
reproduction that perhaps can only be solved by a close study of animals
living together in identical conditions and exhibiting, apparently in
consequence of so living, similar but by no means identical tendencies,
either anatomical or physiological, in certain directions.
One of the most important problems on which the study of the sponges,
coelenterates, and polyzoa of stagnant water throws light is that of the
production of resting buds and similar reproductive bodies adapted to
withstand unfavourable conditions in a quiescent state and to respond to
the renewal of favourable conditions by a renewed growth and activity.
Every autumn, in an English pond or lake, a crisis takes place in the
affairs of the less highly organized inhabitants, and preparations are
made to withstand the unfavourable conditions due directly or indirectly
to the low winter temperature of the water: the individual must perish
but the race may be preserved. At this season _Hydra_, which has been
reproducing its kind by means of buds throughout the summer, develops
eggs with a hard shell that will lie dormant in the mud until next
spring; the phylactolæmatous polyzoa produce statoblasts, the
ctenostomatous polyzoa resting-buds ("hibernacula"), and the sponges
gemmules. Statoblasts, hibernacula, and gemmules are alike produced
asexually, but they resemble the eggs of _Hydra_ in being provided with
a hard, resistant shell, and in having the capacity to lie dormant until
favourable conditions return.
In an Indian pond or lake a similar crisis takes place in the case of
most species, but it does not take place at the same time of year in the
case of all species. Unfortunately the phenomena of periodic
physiological change have been little studied in the freshwater fauna of
most parts of the country, and as yet we know very little indeed of the
biology of the Himalayan lakes and tarns, the conditions in which
resemble those to be found in similar masses of water in Europe much
more closely than they do those that occur in ponds and lakes in a
tropical plain. In Bengal, however, I have been able to devote
considerable attention to the subject, and can state definitely that
some species flourish chiefly in winter and enter the quiescent stage at
the beginning of the hot weather (that is to say about March), while
others reach their maximum development during the "rains" (July to
September) and as a rule die down during winter, which is the driest as
well as the coolest time of year.
The following is a list of the forms that in Bengal are definitely known
to produce hard-shelled eggs, gemmules, resting-buds, or statoblasts
only or most profusely at the approach of the hot weather and to
flourish during winter:--
_Spongilla carteri._
_Sponging alba._
_Spongilla alba_ var. _bengalensis_.
_Spongilla crassissima._
_Hydra vulgaris._
_Victorella bengalensis._
_Plumatella fruticosa._
_Plumatella emarginata._
_Plumatella javanica._
The following forms flourish mainly during the "rains":--
_Spongilla lacustris_ subsp. _reticulata_.
_Trochospongilla latouchiana._
_Trochospongilla phillottiana._
_Stolella indica._
The following flourish throughout the year:--
_Spongilla proliferens._
_Hislopia lacustris._
It is particularly interesting to note that three of the species that
flourish in the mild winter of Bengal, namely _Hydra vulgaris_,
_Plumatella emarginata_, and _P. fruticosa_, are identical with species
that in Europe perish in winter. There is evidence, moreover, that the
statoblasts of the genus to which two of them belong burst more readily,
and thus give rise to new colonies, after being subjected to a
considerable amount of cold. In Bengal they only burst after being
subjected to the heat of the hot weather. Does extreme heat have a
similar effect on aquatic organisms as extreme cold? There is some
evidence that it has.
The species that flourish in India during the rains are all forms which
habitually live near the surface or the edge of ponds or puddles, and
are therefore liable to undergo desiccation as soon as the rains cease
and the cold weather supervenes.
The two species that flourish all the year round do not, properly
speaking, belong to one category, for whereas _Hislopia lacustris_
produces no form of resting reproductive body but bears eggs and
spermatozoa at all seasons, _Spongilla proliferens_ is a short-lived
organism that undergoes a biological crisis every few weeks; that is to
say, it begins to develop gemmules as soon as it is fully formed, and
apparently dies down as soon as the gemmules have attained maturity. The
gemmules apparently lie dormant for some little time, but incessant
reproduction is carried on by means of external buds, a very rare method
of reproduction among the freshwater sponges.
The facts just stated prove that considerable specific idiosyncrasy
exists as regards the biology of the sponges, hydroids, and polyzoa of
stagnant water in Bengal; but an even more striking instance of this
phenomenon is afforded by the sponges _Spongilla bombayensis_ and
_Corvospongilla lapidosa_ in Bombay. These two sponges resemble one
another considerably as regards their mode of growth, and are found
together on the lower surface of stones. In the month of November,
however, _C. lapidosa_ is in full vegetative vigour, while _C.
bombayensis_, in absolutely identical conditions, is already reduced to
a mass of gemmules, having flourished during the "rains." It is thus
clear that the effect of environment is not identical in different
species. This is more evident as regards the groups of animals under
consideration in India (and therefore probably in other tropical
countries) than it is in Europe. The subject is one well worthy of study
elsewhere than in India, for it is significant that specimens of _S.
bombayensis_ taken in November in S. Africa were in a state of activity,
thus contrasting strongly with specimens taken at the same time of year
(though not at the same season from a climatic point of view) in the
Bombay Presidency.
GEOGRAPHICAL DISTRIBUTION OF THE INDIAN SPECIES.
The geographical distribution of the lower invertebrates of fresh and of
stagnant water is often an extremely wide one, probably because the
individual of many species exists at certain seasons or in certain
circumstances in a form that is not only resistant to unfavourable
environment, but also eminently capable of being transported by wind or
currents. We therefore find that some genera and even species are
practically cosmopolitan in their range, while others, so far as our
knowledge goes, appear to have an extraordinarily discontinuous
distribution. The latter phenomenon may be due solely to our ignorance
of the occurrence of obscure genera or species in localities in which
they have not been properly sought for, or it may have some real
significance as indicating that certain forms cannot always increase and
multiply even in those localities that appear most suitable for them. As
an example of universally distributed species we may take the European
polyzoa of the genus _Plumatella_ that occur in India, while of species
whose range is apparently discontinuous better examples could not be
found than the sponges _Trochospongilla pennsylvanica_ and _Spongilla
crateriformis_, both of which are only known from N. America, the
British Isles, and India.
My geographical list of the species of sponges, coelenterates, and
polyzoa as yet found in fresh water in India is modelled on Col.
Alcock's recently published list of the freshwater crabs (Potamonidæ) of
the Indian Empire[B]. I follow him in accepting, with slight
modifications of my own, Blanford's physiographical rather than his
zoogeographical regions, not because I think that the latter have been
or ought to be superseded so far as the vertebrates are concerned, but
rather because the limits of the geographical distribution of aquatic
invertebrates appear to depend on different factors from those that
affect terrestrial animals or even aquatic vertebrates.
[Footnote B: Cat. Ind. Dec. Crust. Coll. Ind. Mus., part i,
fasc. ii (Potamonidæ), 1910.]
"Varieties" are ignored in this list, because they are not considered to
have a geographical significance. The parts of India that are least
known as regards the freshwater representatives of the groups under
consideration are the valley of the Indus, the lakes of Kashmir and
other parts of the Himalayas, the centre of the Peninsula, and the basin
of the Brahmaputra. Those that are best known are the districts round
Bombay, Calcutta, Madras and Bangalore, Travancore and Northern
Tenasserim. Little is known as regards Ceylon, and almost nothing as
regards the countries that surround the Indian Empire, a few species
only having been recorded from Yunnan and the Malay Peninsula, none from
Persia, Afghanistan, or Eastern Turkestan, and only one from Tibet.
Professor Max Weber's researches have, however, taught us something as
regards Sumatra and Java, while the results of various expeditions to
Tropical Africa are beginning to cast light on the lower invertebrates
of the great lakes in the centre of that continent and of the basin of
the Nile.
It is not known to what altitude the three groups range in the Himalayas
and the hills of Southern India. No sponge has been found in Indian
territory at an altitude higher than that of Bhim Tal in Kumaon (4,500
feet), and _Hydra_ is only known from the plains; but a variety of _H.
oligactis_ was taken by Capt. F. H. Stewart in Tibet at an altitude of
about 15,000 feet. _Plumatella diffusa_ flourishes at Gangtok in Sikhim
(6,100 feet), and I have found statoblasts of _P. fruticosa_ in the
neighbourhood of Simla on the surface of a pond situated at an altitude
of about 8,000 feet; Mr. R. Kirkpatrick obtained specimens of the genus
in the Botanical Gardens at Darjiling (6,900 feet), and two species have
been found at Kurseong (4,500-5,000 feet) in the same district.
GEOGRAPHICAL LIST OF THE FRESHWATER SPONGES, HYDROIDS, AND POLYZOA OF
INDIA, BURMA, AND CEYLON.
[A * indicates that a species or subspecies has only been found in one
physiographical region or subregion so far as the Indian Empire is
concerned; a ! that the species has also been found in Europe, a $ in
North America, a + in Africa, and a @ in the Malay Archipelago.]
1. Western Frontier Territory[C].
(Baluchistan, the Punjab, and the N.W. Frontier Province.)
[Footnote C: I include Baluchistan in this territory largely
for climatic reasons.]
SPONGES:--
1. _Spongilla_ (_Eunapius_) _carteri_!@ (Lahore).
HYDROIDS:--
1. _Hydra oligactis_!$ (Lahore).
POLYZOA:--
1. _Plumatella fruticosa_!$ (Lahore).
2. _Plumatella diffusa_!$ (Lahore).
2. Western Himalayan Territory.
(Himalayas from Hazara eastwards as far as Nepal.)
SPONGES:--
1. _Spongilla_ (_Eunapius_) _carteri_!@ (Bhim Tal).
2. _Ephydatia meyeni_@ (Bhim Tal).
HYDROIDS:--None known (_Hydra oligactis_ recorded from Tibet).
POLYZOA:--
1. _Plumatella allmani_! (Bhim Tal).
2. _Plumatella fruticosa_!$ (Simla).
3. _Lophopodella carteri_+ (Bhim Tal).
3. North-Eastern Frontier Territory.
(Sikhim, Darjiling and Bhutan, and the Lower Brahmaputra
Drainage-System.)
SPONGES:--
_Spongilla proliferens_@ (Assam).
HYDROIDS:--None known.
POLYZOA:--
1. _Plumatella fruticosa_! (Kurseong and Assam).
2. _Plumatella diffusa_!$ (Sikhim).
3. _Plumatella javanica_@ (Kurseong).
4. Burma Territory.
(Upper Burma, Arrakan, Pegu, Tenasserim.)
SPONGES:--
1. _Spongilla_ (_Euspongilla_) _proliferens_@ (Upper Burma, Pegu).
2. _Spongilla_ (_Euspongilla_) _crateriformis_!$ (Tenasserim).
3. _Spongilla_ (_Eunapius_) _carteri_!@ (Upper Burma, Pegu,
Tenasserim).
4. _Trochospongilla latouchiana_ (Tenasserim).
5. _Trochospongilla phillottiana_ (Tenasserim).
6. _Tubella vesparioides_* (Tenasserim).
7. _Corvospongilla burmanica_* (Pegu).
HYDROIDS:--
1. _Hydra vulgaris_!$ (Upper Burma and Tenasserim).
POLYZOA:--
1. _Plumatella emarginata_!$ (Pegu, Upper Burma).
2. _Plumatella allmani_! (Tenasserim).
3. _Pectinatella burmanica_ (Tenasserim).
4. _Hislopia lacustris_ (Pegu).
5 _a._ Peninsular Province--Main Area.
(The Peninsula east of the Western Ghats.)
SPONGES:--
1. _Spongilla_ (_Euspongilla_) _lacustris_ subsp. _reticulata_
(Orissa, Madras).
2. _Spongilla_ (_Euspongilla_) _proliferens_@ (Madras).
3. _Spongilla_ (_Euspongilla_) _alba_+ (N. Madras, Orissa, Hyderabad).
4. _Spongilla_ (_Euspongilla_) _hemephydatia_* (Orissa).
5. _Spongilla_ (_Euspongilla_) _crateriformis_!$.
6. _Spongilla_ (_Eunapius_) _carteri_!@.
7. _Spongilla_ (_Eunapius_) _gemina_* (Bangalore).
8. _Spongilla_ (_Stratospongilla_) _bombayensis_+ (Mysore).
9. _Dosilia plumosa_ (N. Madras).
HYDROIDS:--
1. _Hydra vulgaris_!$.
POLYZOA:--
1. _Plumatella fruticosa_! (Madras, Bangalore).
2. _Lophopus_ (?_Lophopodella_), sp. (Madras).
3. _Pectinatella burmanica_ (Orissa).
4. _Victorella bengalensis_ (Madras).
5. _Hislopia lacustris_ (Nagpur).
5b. Peninsular Province--Malabar Zone.
(Western Ghats from Tapti R. to Cape Comorin and eastwards
to the sea.)
SPONGES:--
1. _Spongilla_ (_Euspongilla_) _lacustris_ subsp. _reticulata_
(W. Ghats).
2. _Spongilla_ (_Euspongilla_) _proliferens_@ (Cochin).
3. _Spongilla_ (_Euspongilla_) _alba_+.
4. _Spongilla_ (_Euspongilla_) _cinerea_*.
5. _Spongilla_ (_Euspongilla_) _travancorica_* (Travancore).
6. _Spongilla_ (_Euspongilla_) _crateriformis_!$ (Cochin).
7. _Spongilla_ (_Eunapius_) _carteri_!@.
8. _Spongilla_ (_Stratospongilla_) _indica_* (W. Ghats).
9. _Spongilla _ (_Stratospongilla_) _bombayensis_+ (Bombay, W. Ghats).
10. _Spongilla_ (_Stratospongilla_) _ultima_* (Travancore).
11. _Pectispongilla aurea_* (Travancore, Cochin).
12. _Ephydatia meyeni_@ (Bombay, Travancore).
13. _Dosilia plumosa_ (Bombay).
14. _Trochospongilla pennsylvanica_*!$ (Travancore).
15. _Corvospongilla lapidosa_* (W. Ghats).
HYDROIDS:--None recorded.
POLYZOA:--
1. _Fredericella indica_* (W. Ghats and Travancore).
2. _Plumatella fruticosa_! (Bombay).
3. _Plumatella javanica_@ (Travancore).
4. _Plumatella tanganyikæ_*+ (W. Ghats).
5. _Lophopodella carteri_+ (Bombay, W. Ghats).
6. Indo-Gangetic Plain.
(From Sind to the Brahmaputra.)
SPONGES:--
1. _Spongilla_ (_Euspongilla_) _lacustris_ subsp. _reticulata_
(Gangetic delta).
2. _Spongilla_ (_Euspongilla_) _proliferens_@ (Lower Bengal, etc.).
3. _Spongilla_ (_Euspongilla_) _alba_+ (Lower Bengal).
4. _Spongilla_ (_Euspongilla_) _crateriformis_!$.
5. _Spongilla_ (_Eunapius_) _carteri_!@ (Lower Bengal, etc.).
6. _Spongilla_ (_Eunapius_) _fragilis_ subsp. _calcuttana_* (Lower
Bengal).
7. _Spongilla_ (_Eunapius_) _crassissima_ (Bengal).
8. _Ephydatia meyeni_@ (Lower Bengal).
9. _Trochospongilla latouchiana_ (Lower Bengal).
10. _Trochospongilla phillottiana_ (Lower Bengal).
HYDROIDS:--
1. _Hydra vulgaris_!$.
POLYZOA:--
1. _Plumatella fruticosa_!.
2. _Plumatella emarginata_!$.
3. _Plumatella javanica_@ (Lower Bengal).
4. _Plumatella diffusa_!$.
5. _Plumatella allmani_!.
6. _Plumatella punctata_!$ (Lower Bengal).
7. _Stolella indica_* (Lower Bengal, United Provinces).
8. _Victorella bengalensis_ (Lower Bengal).
9. _Hislopia lacustris_ (United Provinces, N. Bengal).
9a. _Hislopia lacustris_ subsp. _moniliformis_* (Lower Bengal).
7. Ceylon.
SPONGES:--
1. _Spongilla_ (_Euspongilla_) _proliferens_@.
2. _Spongilla_ (_Eunapius_) _carteri_!@.
HYDROIDS:--
1. _Hydra vulgaris_!$.
POLYZOA:--
1. ? _Plumatella emarginata_!$.
2. _Pectinatella burmanica._
The most striking feature of this list is the evidence it affords as to
the distinct character of the fauna of the Malabar Zone, a feature that
is also remarkably clear as regards the Potamonidæ, one genus of which
(_Gecarcinucus_) is peculiar, so far as India is concerned, to that
zone. As regards the sponges we may note the occurrence of no less than
three species of the subgenus _Stratospongilla_, which has not been
found elsewhere in India except on one occasion in Mysore, and of a
species of the genus _Corvospongilla_, which is unknown from the rest of
Peninsular India and from the Himalayas. The genus _Pectispongilla_ is
only known from the Malabar Zone. Among the polyzoa the genus
_Fredericella_[D] appears to be confined, so far as the Indian and
Burmese fauna is concerned, to the Malabar Zone, and the same is true as
regards the group of species to which _Plumatella tanganyikæ_, an
African form, belongs.
[Footnote D: Mr. S. W. Kemp recently obtained at Mangaldai,
near the Bhutan frontier of Assam, a single specimen of what
may be a species of _Fredericella_.]
A further examination of the list of Malabar species and a consideration
of allied forms shows that the majority of the forms restricted to the
Malabar Zone are either African or else closely allied to African forms.
The genus _Corvospongilla_, except for one Burmese species, is otherwise
peculiar to Tropical Africa; while _Stratospongilla_, although not
confined to Africa, is more prolific in species in that continent than
in any other. _Spongilla (Stratospongilla) bombayensis_ has only been
found in Bombay, the Western Ghats, Mysore, and Natal, and _Plumatella
tanganyikæ_ only in the Western Ghats and Central Africa. The genus
_Fredericella_ (which also occurs in Europe, N. America, and Australia)
is apparently of wide distribution in Africa, while _Lophopodella_
(which in India is not confined to the Malabar Zone) is, except for a
Japanese race of the Indian species, restricted outside India, so far as
we know, to East Africa.
A less definite relationship between the sponges and polyzoa of the
Malabar Zone and those of countries to the east of India is suggested by
the following facts:--
(1) The occurrence of the genus _Corvospongilla_ in Burma;
(2) the occurrence of the subgenus _Stratospongilla_ in
Sumatra, China, and the Philippines;
(3) the occurrence of a race of _Lophopodella carteri_ in
Japan;
(4) the occurrence of a species allied to _Plumatella
tanganyikæ_ in the Philippines.
It will be noted that in each of these instances the relationship
extends to Africa as well as to the Eastern countries, and is more
marked in the former direction. The species of _Stratospongilla_,
moreover, that occurs in Sumatra (_S. sumatrensis_) also occurs in
Africa, while those that have been found in China and the Philippines
are aberrant forms.
At first sight it might appear that these extra-Indian relationships
might be explained by supposing that gemmules and statoblasts were
brought to the Malabar Coast from Africa by the aërial currents of the
monsoon or by marine currents and carried from India eastwards by the
same agency, this agency being insufficient to transport them to the
interior and the eastern parts of the Peninsula. The work of La
Touche[E] on wind-borne foraminifera in Rajputana is very suggestive in
this direction; but that the peculiar sponge and polyzoon fauna of
Malabar is due to the agency either of wind or of marine currents may be
denied with confidence, for it is a striking fact that most of the
characteristic genera and subgenera of the Zone have resting
reproductive bodies that are either fixed to solid objects or else are
devoid of special apparatus to render them light. The former is the case
as regards all species of _Corvospongilla_ and all Indian and most other
species of _Stratospongilla_, the gemmules of which not only are
unusually heavy but also adhere firmly; while the statoblasts of
_Fredericella_ have no trace of the air-cells that render the free
statoblasts of all other genera of phylactolæmatous polyzoa peculiarly
light and therefore peculiarly liable to be transported by wind.
[Footnote E: See Mem. Geol. Surv. Ind. XXXV (1), p. 39
(1902).]
A true geographical or geological explanation must therefore be sought
for the relationship between the sponges and polyzoa of Malabar, of
Africa, and of the Eastern countries--a relationship that is well known
to exist as regards other groups of animals. No more satisfactory
explanation has as yet been put forward than that of a former land
connection between Africa and the Malaysia through Malabar at a period
(probably late Cretaceous) when the Western Ghats were much higher than
they now are[F].
[Footnote F: See Ortmann, "The Geographical Distribution of
Freshwater Decapods and its bearing upon Ancient Geography,"
Proc. Amer. Phil. Soc. xli, p. 380, fig. 6 (1902); also
Suess, "The Face of the Earth" (English ed.) i, p. 416
(1904).]
There is little to be said as regards the distribution of the sponges,
hydroids, and polyzoa of fresh water in other parts of India. It may be
noted, however, that the species known from the Punjab are all widely
distributed Palæarctic forms, and that the genus _Stolella_ is
apparently confined to the Indo-Gangetic Plain. Two species of sponge
are peculiar to Lower Burma, one of them (_Corvospongilla burmanica_)
representing the geographical alliance already discussed as regards the
Malabar Zone, the other (_Tubella vesparioides_) closely related to a
Malaysian species (_T. vesparium_ from Borneo) and perhaps representing
the northern limit of the Malaysian element well known in the fauna of
Lower Burma. Of the sponges and polyzoa of Ceylon we know as yet too
little to make it profitable to discuss their affinities. All that have
as yet been discovered occur also in Peninsular India; nor do they
afford any evidence of a connection with the Malabar Zone.
The question of the geographical range of the sponges, hydroids, and
polyzoa of brackish water may be considered briefly, for it is of
importance in considering that of those which are confined to fresh
water. Some of these species from brackish water (e. g., _Membranipora
lacroixii_) are identical with others (e. g., _Victorella bengalensis_
and _Bowerbankia caudata_ subsp. _bengalensis_) closely related to
European forms. Others again (e. g., _Loxosomatoides colonialis_ and
_Sagartia schilleriana_) are known as yet from the Ganges delta only. In
our ignorance of the Indian representatives of the groups to which they
belong, it is impossible to assert that their distribution is actually
so restricted as it seems.
SOME SPECIAL LOCALITIES.
In order to avoid constant repetition as regards the conditions that
prevail at the places most frequently mentioned in this volume, a few
details as regards them may be conveniently stated here.
_Lower Bengal._
CALCUTTA is situated on the River Hughli at a point about 90 miles from
the open sea. The water of the river is practically fresh, but is
strongly affected by the tides; it is always turbid and of a brownish
colour. The river, however, is not a good collecting ground for sponges,
coelenterates, and polyzoa, and none of the species described in this
volume have been obtained from it. It is in the Calcutta "tanks" that
most of my investigations have been made. These tanks are ponds, mostly
of artificial origin, very numerous, of varying size but never very
large or deep. Most of them contain few solid objects to which sedentary
organisms can fix themselves, and such ponds are of course poor in
sponges and polyzoa. Others, however, support a prolific growth of weeds
such as _Pistia stratiotes_, _Lemna_, and _Limnanthemum_, and a few have
brickwork or artificial stonework at their sides. In those parts of the
town that approach the Salt Lakes (large lagoons and swamps of brackish
water connected with the sea by the Mutlah River) the water of the ponds
is slightly brackish and permits few plants except algæ to flourish. Few
of the bigger tanks ever dry up. The best of the tanks from the
sponge-collector's point of view, so far as I have been able to
discover, is the one in the compound of the Indian Museum. It enjoys all
the advantages of light and shade, solid supports, prolific aquatic
vegetation, considerable depth, and the vicinity of human dwellings that
seem to be favourable to the growth of sponges, no less than nine
species of which, representing three genera and two subgenera, grow
abundantly in it. _Hydra_ also flourishes in this pond, but for some
reasons there are few polyzoa. The phylactolæmatous species of the
latter group, however, are extraordinarily abundant in one of the tanks
in the Zoological Gardens at Alipore. In this tank, which unlike the
Museum tank is directly connected with the river, no less than six
species and varieties of the genus _Plumatella_ have been found growing
together on sticks, floating seeds, and water-plants. Except _Hislopia_,
which is common on _Vallisneria_ in one tank on the Maidan (opposite the
Bengal Club), the ctenostomes of stagnant water are only found in the
tanks near the Salt Lakes.
PORT CANNING is situated on the Mutlah River about 30 miles from
Calcutta and about 60 from the open sea. The Mutlah is really a tidal
creek rather than a river, in spite of the fact that it runs for a
considerable number of miles, and its waters are distinctly brackish.
Water taken from the edge at Port Canning in March was found to contain
25.46 per thousand of saline residue. The interesting feature of Port
Canning, however, is from a zoological point of view not the Mutlah but
certain ponds of brackish water now completely separated from it, except
occasionally when the river is in flood, but communicating regularly
with it in the memory of living persons. These ponds, which were
apparently not in existence in 1855, have on an average an area of about
half an acre each, and were evidently formed by the excavation of earth
for the construction of an embankment along the Mutlah. They are very
shallow and lie exposed to the sun. The salinity differs considerably in
different ponds, although the fauna seems to be identical; the water of
one pond was found to contain 22.88 per thousand of saline residue in
May, 20.22 per thousand in March, and 12.13 in December. A second pond
in the neighbourhood of the first and apparently similar to it in every
way contained only 9.82 per thousand in July, after the rains had
broken. The fauna of these ponds includes not only a freshwater sponge
(_Spongilla alba_ var. _bengalensis_) but also many aquatic insects
(_e. g._, larvæ of mosquitos and of _Chironomus_ and several species of
beetles and Rhynchota); while on the other hand essentially marine
coelenterates (_Irene ceylonensis_, etc.) and worms (_e. g._, the
gephyrean _Physcosoma lurco_[G]) form a part of it, together with forms
of intermediate habitat such as _Bowerbankia caudata_ subsp.
_bengalensis_, _Victorella bengalensis_, and several fish and crustacea
common in brackish water.
[Footnote G: I am indebted to Mr. W. F. Lanchester for the
identification of this species.]
_Orissa._
Orissa may be described in general terms as consisting of the coastal
area of Bengal south of the Gangetic delta. It extends in inland,
however, for a considerable distance and includes hilly tracts. There is
no geographical boundary between it and the north-eastern part of the
Madras Presidency or the eastern part of the Central Provinces.
CHILKA LAKE.--This marine lake is a shallow lagoon measuring about 40
miles in length and 10 miles in breadth, and formed in geologically
recent times by the growth of a narrow sand-bank across the mouth of a
wide bay. At its northern end it communicates with the sea by a narrow
channel, and throughout its length it is strongly affected by the tides.
At its south end, which is actually situated in the Ganjam district of
Madras, the water is distinctly brackish and is said to be nearly fresh
at certain times of year. At this end there are numerous small
artificial pools of brackish water somewhat resembling those of Port
Canning as regards their fauna.
SUR (or SAR) LAKE.--A shallow, freshwater lake of very variable size
situated a few miles north of Puri on the Orissa coast. In origin it
probably resembled the Chilka Lake, but it is now separated from the sea
by about 3 miles of barren sand dunes, among which numerous little pools
of rain-water are formed during the rains. These dry up completely in
winter, and even the lake itself is said sometimes almost to disappear,
although when it is full it is several miles in length. The fauna is
essentially a freshwater one, but includes certain Mysidæ and other
crustacea usually found in brackish water.
_Bombay Presidency._
BOMBAY.--The town of Bombay, built on an island near the mainland, is
situated close to swamps and creeks of brackish water not unlike those
that surround Calcutta. Its "tanks," however, differ from those of
Calcutta in having rocky bottoms and, in many cases, in drying up
completely in the hot weather. Of the fauna of the swamps extremely
little is known, but so far as the sponges and polyzoa of the tanks are
concerned the work undertaken by Carter was probably exhaustive.
IGATPURI.--Igatpuri is situated at an altitude of about 2000 feet, 60
miles north-east of Bombay. Above the town there is a lake of several
square miles in area whence the water-supply of several stations in the
neighbourhood is obtained. The water is therefore kept free from
contamination. The bottom is composed of small stones and slopes
gradually up at the edges. During the dry weather its level sinks
considerably. Several interesting sponges and polyzoa have been found in
this lake, most of them also occurring in a small pond in the
neighbourhood in which clothes are washed and the water is often full of
soap-suds.
_Southern India._
MADRAS.--The city of Madras is built by the sea, straggling over a large
area of the sandy soil characteristic of the greater part of the east
coast of India. In wet weather this soil retains many temporary pools of
rain-water, and there are numerous permanent tanks of no great size in
the neighbourhood of the town. The so-called Cooum River, which flows
through the town, is little more than a tidal creek, resembling the
Mutlah River of Lower Bengal on a much smaller scale. The sponges and
polyzoa as yet found in the environs of Madras are identical with those
found in the environs of Calcutta.
BANGALORE.--Bangalore (Mysore State) is situated near the centre of the
Madras Presidency on a plateau about 3000 feet above sea-level. The
surrounding country is formed of laterite rock which decomposes readily
and forms a fine reddish silt in the tanks. These tanks are numerous,
often of large size, and as a rule at least partly of artificial origin.
Their water supports few phanerogamic plants and is, as my friend Dr.
Morris Travers informs me, remarkably free from salts in solution. The
sponge fauna of the neighbourhood of Bangalore appears to be
intermediate between that of Madras and that of Travancore.
THE BACKWATERS OF COCHIN AND TRAVANCORE.--The "backwaters" of Cochin and
Travancore were originally a series of shallow lagoons stretching along
the coast of the southern part of the west coast of India for a distance
of considerably over a hundred miles. They have now been joined together
by means of canals and tunnels to form a tidal waterway, which
communicates at many points directly with the sea. The salinity of the
water differs greatly at different places and in different seasons, and
at some places there is an arrangement to keep out sea-water while the
rice-fields are being irrigated. The fauna is mainly marine, but in the
less saline parts of the canals and lakes many freshwater species are
found.
_Shasthancottah._--There are two villages of this name, one situated on
the backwater near Quilon (coast of Travancore), the other about three
miles inland on a large freshwater lake. This lake, which does not
communicate with the backwater, occupies a narrow winding rift several
miles in length at a considerable depth below the surrounding country.
Its bottom is muddy and it contains few water-plants, although in some
places the water-plants that do exist are matted together to form
floating islands on which trees and bushes grow. The fauna, at any rate
as regards mollusca and microscopic organisms, is remarkably poor, but
two species of polyzoa (_Fredericella indica_ and _Plumatella
fruticosa_) and one of sponge (_Trochospongilla pennsylvanica_) grow in
considerable abundance although not in great luxuriance.
_The Himalayas._
BHIM TAL[H] is a lake situated at an altitude of 4500 feet in that part
of the Western Himalayas known as Kumaon, near the plains. It has a
superficial area of several square miles, and is deep in the middle. Its
bottom and banks are for the most part muddy. Little is known of its
fauna, but two polyzoa (_Plumatella allmani_ and _Lophopodella carteri_)
and the gemmules of two sponges (_Spongilla carteri_ and _Ephydatia
meyeni_) have been found in it.
[Footnote H: The fauna of this lake and of others in the
neighbourhood has recently been investigated by Mr. S. W.
Kemp. See the addenda at the end of this volume.--_June
1911._]
* * * * *
NOMENCLATURE AND TERMINOLOGY.
The subject of nomenclature may be considered under four heads:--(I.)
the general terminology of the various kinds of groups of individuals
into which organisms must be divided; (II.) the general nomenclature of
specimens belonging to particular categories, such as types, co-types,
etc.; (III.) the nomenclature that depends on such questions as that of
"priority"; and (IV.) the special terminology peculiar to the different
groups. The special terminology peculiar to the different groups is
dealt with in the separate introductions to each of the three parts of
this volume.
(I.)
No group of animals offers greater difficulty than the sponges,
hydroids, and polyzoa (and especially the freshwater representatives of
these three groups) as regards the question "What is a species?" and the
kindred questions, "What is a subspecies?" "What is a variety?" and
"What is a phase?" Genera can often be left to look after themselves,
but the specific and kindred questions are answered in so many different
ways, if they are even considered, by different systematists, especially
as regards the groups described in this volume, that I feel it necessary
to state concisely my own answers to these questions, not for the
guidance of other zoologists but merely to render intelligible the
system of classification here adopted. The following definitions should
therefore be considered in estimating the value of "species," etc.,
referred to in the following pages.
_Species._--A group of individuals differing in constant characters of a
definite nature and of systematic[I] importance from all others in the
same genus.
[Footnote I: "What characters are of systematic importance?"
is a question to which different answers must be given in
the case of different groups.]
_Subspecies._--An isolated or local race, the individuals of which
differ from others included in the same species in characters that are
constant but either somewhat indefinite or else of little systematic
importance.
_Variety._--A group of individuals not isolated geographically from
others of the same species but nevertheless exhibiting slight, not
altogether constant, or indefinite differences from the typical form of
the species (_i. e._, the form first described).
_Phase._--A peculiar form assumed by the individuals of a species which
are exposed to peculiarities in environment and differ from normal
individuals as a direct result.
There are cases in which imperfection of information renders it
difficult or impossible to distinguish between a variety and a
subspecies. In such cases it is best to call the form a variety, for
this term does not imply any special knowledge as regards its
distribution or the conditions in which it is found.
I use the term "form" in a general sense of which the meaning or
meanings are clear without explanation.
(II.)
The question of type specimens must be considered briefly. There are two
schools of systematists, those who assert that one specimen and one only
must be the type of a species, and those who are willing to accept
several specimens as types. From the theoretical point of view it seems
impossible to set up any one individual as the ideal type of a species,
but those who possess collections or are in charge of museums prefer,
with the natural instinct of the collector, to have a definite single
type (of which no one else can possibly possess a duplicate) in their
possession or care, and there is always the difficulty that a zoologist
in describing a species, if he recognizes more than one type, may
include as types specimens that really belong to more than one species.
These difficulties are met by some zoologists by the recognition of
several specimens as paratypes, all of equal value; but this, after all,
is merely a terminological means of escaping from the difficulty,
calculated to salve the conscience of a collector who feels unwilling to
give up the unique type of a species represented by other specimens in
his collection. The difficulty as regards the confounding of specimens
of two or more species as the types of one can always be adjusted if the
author who discovers the mistake redescribes one of the species under
the original name and regards the specimen that agrees with his
description as the type, at the same time describing a new species with
another of the specimens as its type. Personally I always desire to
regard the whole material that forms the basis of an original
description of a species as the type, but museum rules often render this
impossible, and the best that can be done is to pick out one specimen
that seems particularly characteristic and to call it the type, the rest
of the material being termed co-types. A peculiar difficulty arises,
however, as regards many of the sponges, coelenterates, and polyzoa,
owing to the fact that they are often either compound animals, each
specimen consisting of more than one individual, or are easily divisible
into equivalent fragments. If the single type theory were driven to its
logical conclusion, it would be necessary to select one particular polyp
in a hydroid colony, or even the part of a sponge that surrounded a
particular osculum as the type of the species to which the hydroid or
the sponge belonged. Either by accident or by design specimens of
Spongillidæ, especially if kept dry, are usually broken into several
pieces. There is, as a matter of fact, no reason to attribute the
peculiarly sacrosanct nature of a type to one piece more than another.
In such cases the biggest piece may be called the type, while the
smaller pieces may be designated by the term "schizotype."
The more precise definition of such terms as topotype, genotype, _et
hujus generis omnis_ is nowadays a science (or at any rate a form of
technical industry) by itself and need not be discussed here.
(III.)
In 1908 an influential committee of British zoologists drew up a
strenuous protest against the unearthing of obsolete zoological names
(see 'Nature,' Aug. 1908, p. 395). To no group does this protest apply
with greater force than to the three discussed in this volume. It is
difficult, however, to adopt any one work as a standard of nomenclature
for the whole of any one of them. As regards the Spongillidæ it is
impossible to accept any monograph earlier than Potts's "Fresh-Water
Sponges" (P. Ac. Philad., 1887), for Bowerbank's and Carter's earlier
monographs contained descriptions of comparatively few species. Even
Potts's monograph I have been unable to follow without divergence, for
it seems to me necessary to recognize several genera and subgenera that
he ignored. The freshwater polyzoa, however, were dealt with in so
comprehensive a manner by Allman in his "Fresh-Water Polyzoa" (London,
1856) that no difficulty is experienced in ignoring, so far as
nomenclature is concerned, any earlier work on the group; while as
regards other divisions of the polyzoa I have followed Hincks's "British
Marine Polyzoa" (1880), so far as recent researches permit. In most
cases I have not attempted to work out an elaborate synonymy of species
described earlier than the publication of the works just cited, for to
do so is a mere waste of time in the case of animals that call for a
most precise definition of species and genera and yet were often
described, so far as they were known earlier than the dates in question,
in quite general terms. I have been confirmed in adopting this course by
the fact that few of the types of the earlier species are now in
existence, and that a large proportion of the Indian forms have only
been described within the last few years.
MATERIAL.
The descriptions in this volume are based on specimens in the collection
of the Indian Museum, the Trustees of which, by the liberal manner in
which they have permitted me to travel in India and Burma on behalf of
the Museum, have made it possible not only to obtain material for study
and exchange but also to observe the different species in their natural
environment. This does not mean to say that specimens from other
collections have been ignored, for many institutions and individuals
have met us generously in the matter of gifts and exchanges, and our
collection now includes specimens of all the Indian forms, named in
nearly all cases by the author of the species, except in those of
species described long ago of which no authentic original specimens can
now be traced. Pieces of the types of all of the Indian Spongillidæ
described by Carter have been obtained from the British Museum through
the kind offices of Mr. R. Kirkpatrick. The Smithsonian Institution has
sent us from the collection of the United States National Museum
specimens named by Potts, and the Berlin Museum specimens named by
Weltner, while to the Imperial Academy of Sciences of St. Petersburg we
owe many unnamed but interesting sponges. Dr. K. Kraepelin and Dr. W.
Michaelsen have presented us with specimens of most of the species and
varieties of freshwater polyzoa described by the former in his great
monograph and elsewhere. We owe to Dr. S. F. Harmer, formerly of the
Cambridge University Museum and now Keeper in Zoology at the British
Museum, to Professor Max Weber of Amsterdam, Professor Oka of Tokyo, and
several other zoologists much valuable material. I would specially
mention the exquisite preparations presented by Mr. C. Rousselet.
Several naturalists in India have also done good service to the Museum
by presenting specimens of the three groups described in this volume,
especially Major H. J. Walton, I.M.S., Major J. Stephenson, I.M.S., Dr.
J. R. Henderson and Mr. G. Matthai of Madras, and Mr. R. Shunkara
Narayana Pillay of Trivandrum.
The following list shows where the types of the various species,
subspecies, and varieties are preserved, so far as it has been possible
to trace them. I have included in this list the names of all species
that have been found in stagnant water, whether fresh or brackish, but
those of species not yet found in fresh water are enclosed in square
brackets.
+-----------------------------------------------------------------------+
| INDIAN SPONGILLIDÆ. |
| |
+---------------------------------+----------------------+--------------+
| NAME. | TYPE IN COLL. | MATERIAL |
| | | EXAMINED. |
+---------------------------------+----------------------+--------------+
| _Spongilla lacustris_ subsp. | Ind. Mus. | Type. |
| _reticulata_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla proliferens_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Spongilla alba_ | Brit. and Ind. Mus. | Schizotype. |
+---------------------------------+----------------------+--------------+
| [_Spongilla alba_ var. | Ind. Mus. | Type |
| _bengalensis_] | | |
+---------------------------------+----------------------+--------------+
| _Spongilla alba_ var. | Brit. Mus. | {Specimens |
| _cerebellata_ | | {compared |
| | | {with type. |
+---------------------------------+----------------------+--------------+
| _Spongilla cinerea_ | Brit. and Ind. Mus. | Schizotype. |
+---------------------------------+----------------------+--------------+
| [_Spongilla travancorica_] | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Spongilla hemephydatia_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Spongilla crateriformis_ | U.S. Nat. Mus. | Co-type. |
+---------------------------------+----------------------+--------------+
| _Spongilla carteri_ | Brit. and Ind. Mus. | Schizotype. |
+---------------------------------+----------------------+--------------+
| _Spongilla carteri_ var. | Ind. Mus. | Type. |
| _mollis_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla carteri_ var. | " " | " |
| _cava_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla carteri_ var. | " " | " |
| _lobosa_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla fragilis_ subsp. | " " | " |
| _calcuttana_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla fragilis_ subsp. | Amsterdam Mus. | Co-type. |
| _decipiens_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla gemina_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Spongilla crassissima_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Spongilla crassissima_ var. | " " | " |
| _crassior_ | | |
+---------------------------------+----------------------+--------------+
| _Spongilla bombayensis_ | Brit. and Ind. Mus. | Schizotype. |
+---------------------------------+----------------------+--------------+
| _Spongilla indica_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Spongilla ultima_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Pectispongilla aurea_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Ephydatia meyeni_ | Brit. and Ind. Mus. | Schizotype. |
+---------------------------------+----------------------+--------------+
| _Dosilia plumosa_ | " " " " | " |
+---------------------------------+----------------------+--------------+
| _Trochospongilla latouchiana_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Trochospongilla phillottiana_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Trochospongilla pennsylvanica_ | U.S. Nat. Mus. | Co-type. |
+---------------------------------+----------------------+--------------+
| _Tubella vesparioides_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Corvospongilla burmanica_ | Brit. and Ind. Mus. | Schizotype. |
+---------------------------------+----------------------+--------------+
| _Corvospongilla lapidosa_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| INDIAN COELENTERATES OF STAGNANT WATER. |
+---------------------------------+----------------------+--------------+
| HYDROZOA. | | |
+---------------------------------+----------------------+--------------+
| _Hydra oligactis_ | Not in existence. | |
+---------------------------------+----------------------+--------------+
| _Hydra vulgaris_ | " " | |
+---------------------------------+----------------------+--------------+
| [_Syncoryne filamentata_] | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| [_Bimeria vestita_] | ? Not in existence. | |
+---------------------------------+----------------------+--------------+
| [_Irene ceylonensis_] | {Hydroid in Ind.} | Hydroid type |
| | {Mus., Medusa} | |
| | {in Brit. Mus.} | |
+---------------------------------+----------------------+--------------+
| ACTINIARIA. | | |
+---------------------------------+----------------------+--------------+
| [_Sagartia schilleriana_] | Ind. Mus. | Types. |
+---------------------------------+----------------------+--------------+
| [_Sagartia schilleriana_ | " " | " |
| subsp. _exul_] | | |
+---------------------------------+----------------------+--------------+
| INDIAN POLYZOA OF STAGNANT WATER. |
+---------------------------------+----------------------+--------------+
| ENTOPROCTA. | | |
+---------------------------------+----------------------+--------------+
| [_Loxosomatoides colonialis_] | Ind. Mus. | Types. |
+---------------------------------+----------------------+--------------+
| ECTOPROCTA CHEILOSTOMATA. | | |
+---------------------------------+----------------------+--------------+
| [_Membranipora lacroixii_] | ? Paris Mus. | |
+---------------------------------+----------------------+--------------+
| [_Membranipora bengalensis_] | Ind. Mus. | Types. |
+---------------------------------+----------------------+--------------+
| ECTOPROCTA STENOSTOMATA. | | |
+---------------------------------+----------------------+--------------+
| [_Bowerbankia caudata_ subsp. | Ind. Mus. | Types. |
| _bengalensis_] | | |
+---------------------------------+----------------------+--------------+
| _Victorella bengalensis_ | " " | " |
+---------------------------------+----------------------+--------------+
| _Hislopia lacustris_ | ? Not in existence. | |
+---------------------------------+----------------------+--------------+
| _Hislopia lacustris_ subsp. | Ind. Mus. | " |
| _moniliformis_ | | |
+---------------------------------+----------------------+--------------+
| ECTOPROCTA PHYLACTOLÆMATA. | | |
+---------------------------------+----------------------+--------------+
| _Fredericella indica_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Plumatella fruticosa_ | Not in existence. | |
+---------------------------------+----------------------+--------------+
| _Plumatella diffusa_ |?Philadelphia Acad.[J]| |
+---------------------------------+----------------------+--------------+
| _Plumatella allmani_ | Not in existence. | |
+---------------------------------+----------------------+--------------+
| _Plumatella emarginata_ | " " | |
+---------------------------------+----------------------+--------------+
| | {Hamburg and} | One of the |
| _Plumatella javanica_ | {Ind. Mus. } | types. |
+---------------------------------+----------------------+--------------+
| | {Brit. and Ind.} | One of the |
| _Plumatella tanganyikæ_ | {Mus. } | types. |
+---------------------------------+----------------------+--------------+
| _Stolella indica_ | Ind. Mus. | Type. |
+---------------------------------+----------------------+--------------+
| _Lophopodella carteri_ | Brit. Mus. | " |
+---------------------------------+----------------------+--------------+
| _Lophopodella carteri_ var. | Ind. Mus. | " |
| _himalayana_ | | |
+---------------------------------+----------------------+--------------+
| _Pectinatella burmanica_ | Ind. Mus. | " |
+---------------------------------+----------------------+--------------+
[Footnote J: I have failed to obtain from the Philadelphia
Academy of Science a statement that the type of this species
is still in existence.]
The literature dealing with the various groups described in the volume
is discussed in the introductions to the three parts. Throughout the
volume I have, so far as possible, referred to works that can be
consulted in Calcutta in the libraries of the Indian Museum, the
Geological Survey of India, or the Asiatic Society of Bengal. The names
of works that are not to be found in India are marked with a *. The
rarity with which this mark occurs says much for the fortunate position
in which zoologists stationed in Calcutta find themselves as regards
zoological literature, for I do not think that anything essential has
been omitted.
It remains for me to express my gratitude to those who have assisted me
in the preparation of this volume. The names of those who have
contributed specimens for examination have already been mentioned. I
have to thank the Trustees of the Indian Museum not only for their
liberal interpretation of my duties as an officer of the Museum but also
for the use of all the drawings and photographs and some of the blocks
from which this volume is illustrated. Several of the latter have
already been used in the "Records of the Indian Museum." From the Editor
of the "Fauna" I have received valuable suggestions, and I am indebted
to Dr. Weltner of the Berlin Museum for no less valuable references to
literature. Mr. F. H. Gravely, Assistant Superintendent in the Indian
Museum, has saved me from several errors by his criticism.
The majority of the figures have been drawn by the draftsmen of the
Indian Museum, Babu Abhoya Charan Chowdhary, and of the Marine Survey of
India, Babu Shib Chandra Mondul, to both of whom I am much indebted for
their accuracy of delineation.
No work dealing with the sponges of India would be complete without a
tribute to the memory of H. J. Carter, pioneer in the East of the study
of lower invertebrates, whose work persists as a guide and an
encouragement to all of us who are of the opinion that biological
research on Indian animals can only be undertaken in India, and that
even systematic zoological work can be carried out in that country with
success. I can only hope that this, the first volume in the official
Fauna of the Indian Empire to be written entirely in India, may prove
not unworthy of his example.
Indian Museum, Calcutta Oct. 23rd, 1910.
PART I.
FRESHWATER SPONGES
(SPONGILLIDÆ).
INTRODUCTION TO PART I.
I.
THE PHYLUM PORIFERA.
The phylum Porifera or Spongiæ includes the simplest of the Metazoa or
multicellular animals. From the compound Protozoa its members are
distinguished by the fact that the cells of which they are composed
exhibit considerable differentiation both in structure and in function,
and are associated together in a definite manner, although they are not
combined to form organs and systems of organs as in the higher Metazoa.
Digestion, for instance, is performed in the sponges entirely by
individual cells, into the substance of which the food is taken, and the
products of digestion are handed on to other cells without the
intervention of an alimentary canal or a vascular system, while there is
no structure in any way comparable to the nervous system of more highly
organized animals.
The simplest form of sponge, which is known as an olynthus, is a hollow
vase-like body fixed at one end to some solid object, and with an
opening called the osculum at the other. The walls are perforated by
small holes, the pores, from which the name Porifera is derived.
Externally the surface is protected by a delicate membrane formed of
flattened cells and pierced by the pores, while the interior of the vase
is covered with curious cells characteristic of the sponges, and known
as choanocytes or collar-cells. They consist of minute oval or
pear-shaped bodies, one end of which is provided with a rim or collar of
apparently structureless membrane, while a flagellum or whip-like lash
projects from the centre of the surface surrounded by the collar. These
collar-cells are practically identical with those of which the Protozoa
known as Choanoflagellata consist; but it is only in the sponges[K] that
they are found constantly associated with other cells unlike themselves.
[Footnote K: Except in "_Proterospongia_," an organism of
doubtful affinities but not a sponge. It consists of a mass
of jelly containing ordinary cells, with collar-cells
_outside_.]
In addition to the collar-cells, which form what is called the gastral
layer, and the external membrane (the derma or dermal membrane), the
sponge contains cells of various kinds embedded in a structureless
gelatinous substance, through which they have the power of free
movement. Most of these cells have also the power of changing their form
in an "amoeboid" manner; that is to say, by projecting and withdrawing
from their margin mobile processes of a more or less finger-like form,
but unstable in shape or direction. The protoplasm of which some of the
cells are formed is granular, while that of others is clear and
translucent. Some cells, which (for the time being at any rate) do not
exhibit amoeboid movements, are glandular in function, while others
again give rise in various ways to the bodies by means of which the
sponge reproduces its kind. There is evidence, however, that any one
kind of cell, even those of the membrane and the gastral layer, can
change its function and its form in case of necessity.
Most sponges possess a supporting framework or skeleton. In some it is
formed entirely of a horny substance called spongin (as in the
bath-sponge), in others it consists of spicules of inorganic matter
(either calcareous or siliceous) secreted by special cells, or of such
spicules bound together by spongin. Extraneous objects, such as
sand-grains, are frequently included in the skeleton. The spongin is
secreted like the spicules by special cells, but its chemical structure
is much more complicated than that of the spicules, and it is not
secreted (at any rate in most cases) in such a way as to form bodies of
a definite shape. In the so-called horny sponges it resembles the chitin
in which insects and other arthropods are clothed.
* * * * *
In no adult sponge do the collar-cells completely cover the whole of the
internal surface, the olynthus being a larval form, and by no means a
common larval form. It is only found in certain sponges with calcareous
spicules. As the structure of the sponge becomes more complicated the
collar-cells are tucked away into special pockets or chambers known as
ciliated chambers, and finally the approach to these chambers, both from
the external surface and from the inner or gastral cavity, takes the
form of narrow tubes or canals instead of mere pores. With further
complexity the simple internal cavity tends to disappear, and the sponge
proliferates in such a way that more than one osculum is formed. In the
class Demospongiæ, to which the sponges described in this volume belong,
the whole system is extremely complicated.
The skeleton of sponges, when it is not composed wholly of spongin,
consists of, or at any rate contains, spicules that have a definite
chemical composition and definite shapes in accordance with the class,
order, family, genus, and species of the sponge. Formerly sponges were
separated into calcareous, siliceous, and horny sponges by the nature of
their skeleton; and although the system of classification now adopted
has developed into a much more complex one and a few sponges are known
that have both calcareous and siliceous spicules, the question whether
the spicules are formed of salts of lime or of silica (strictly speaking
of opal) is very important. All Demospongiæ that have spicules at all
have them of the latter substance, and the grade Monaxonida, in which
the freshwater sponges constitute the family Spongillidæ, is
characterized by the possession of spicules that have typically the form
of a needle pointed at both ends. Although spicules of this simple form
may be absent in species that belong to the grade, the larger spicules,
which are called megascleres, have not normally more than one main axis
and are always more or less rod-like in outline. They are usually
arranged so as to form a reticulate skeleton. Frequently, however, the
megascleres or skeleton-spicules are not the only spicules present, for
we find smaller spicules (microscleres) of one or more kinds lying loose
in the substance of the sponge and in the external membrane, or, in the
Spongillidæ only, forming a special armature for the reproductive bodies
known as gemmules.
All sponges obtain their food in the same way, namely by means of the
currents of water set up by the flagella of the collar-cells. These
flagella, although apparently there is little concerted action among
them, cause by their rapid movements changes of pressure in the water
contained in the cavities of the sponge. The water from outside
therefore flows in at the pores and finally makes its way out of the
oscula. With the water minute particles of organic matter are brought
into the sponge, the collar-cells of which, and probably other cells,
have the power of selecting and engulfing suitable particles. Inside the
cells these particles undergo certain chemical changes, and are at least
partially digested. The resulting substances are then handed on directly
to other cells, or, as some assert, are discharged into the common
jelly, whence they are taken up by other cells.
Sponges reproduce their kind in more ways than one, _viz._, by means of
eggs (which are fertilized as in other animals by spermatozoa), by means
of buds, and by means of the peculiar bodies called gemmules the
structure and origin of which is discussed below (p. 42). They are of
great importance in the classification of the Spongillidæ. Sponges can
also be propagated artificially by means of fission, and it is probable
that this method of reproduction occurs accidentally, if not normally,
in natural circumstances.
GENERAL STRUCTURE OF THE SPONGILLIDÆ.
It would be impracticable in this introduction to give a full account of
the structure of the Spongillidæ, which in some respects is still
imperfectly known. Students who desire further information should
consult Professor Minchin's account of the sponges in Lankester's
'Treatise on Zoology,' part ii, or, if a less technical description is
desired, Miss Sollas's contribution to the 'Cambridge Natural History,'
vol. i, in which special attention is paid to _Spongilla_.
The diagram reproduced in fig. 1 gives a schematic view of a vertical
section through a living freshwater sponge. Although it represents the
structure of the organism as being very much simpler than is actually
the case, and entirely omits the skeleton, it will be found useful as
indicating the main features of the anatomy.
[Illustration: Fig. 1.--Diagram of a vertical section through a
freshwater sponge (_modified from Kükenthal_).
A=pores; B=subdermal cavity; C=inhalent canal; D=ciliated chamber;
E=exhalent canal; F=osculum; G=dermal membrane; H=eggs; J=gemmule.]
It will be noted that the diagram represents an individual with a single
osculum or exhalent aperture. As a rule adult Demospongiæ have several
or many oscula, but even in the Spongillidæ sponges occur in which there
is only one. New oscula are formed by a kind of proliferation that
renders the structure still more complex than it is when only one
exhalent aperture is present.
The little arrows in the figure indicate the direction of the currents
of water that pass through the sponge. It enters through small holes in
the derma into a subdermal cavity, which separates the membrane from the
bulk of the sponge. This space differs greatly in extent in different
species. From the subdermal space the water is forced by the action of
the flagella into narrow tubular canals that carry it into the ciliated
chambers. Thence it passes into other canals, which communicate with
what remains of the central cavity, and so out of the oscula.
The ciliated chambers are very minute, and the collar-cells excessively
so. It is very difficult to examine them owing to their small size and
delicate structure. Fig. 2 D represents a collar-cell of a sponge seen
under a very high power of the microscope in ideal conditions.
[Illustration: Fig. 2.--Sponge cells.
A=bubble-cells of _Ephydatia mülleri_, × 350 (_after Weltner_).
B=gemmule-cell of _Spongilla lacustris_ containing green corpuscles
(shaded dark), × 800 (_after Weltner_). C=gemmule-cell of _Ephydatia
blembingia_ showing "tabloids" of food-material, × 1150 (_after Evans_).
D=collar-cell of _Esperella ægagrophila_, × 1600 (_after Vosmaer and
Pekelharing_). E=three stages in the development of a gemmule-spicule of
_E. blembingia_ (_after Evans_), × 665. F=outline of porocytes of _S.
proliferens_, × ca. 1290: _e_=dermal cell; _n_=nucleus; _p_=pore;
_p.c._=pore-cell.]
The nature of the inhalent apertures in the external membrane has been
much discussed as regards the Demospongiæ, but the truth seems to be
that their structure differs considerably even in closely allied
species. At any rate this is the case as regards the Indian _Spongillæ_.
In all species the membrane is composed of flattened cells of irregular
shape fitted together like the pieces of a puzzle-picture. In some
species (e. g., _Spongilla carteri_) the apertures in the membrane
consist merely of spaces between adjacent cells, which may be a little
more crowded together than is usual. But in others (e. g., _Spongilla
proliferens_ and _Spongilla crassissima_) in which the pores are
extremely small, each pore normally pierces the middle of a flat,
ring-shaped cell or porocyte. Occasionally, however, a pore may be found
that is enclosed by two narrow, crescent-shaped cells joined together at
their tips to form a ring. The porocytes of sponges like _Spongilla
carteri_ are probably not actually missing, but instead of being in the
external membrane are situated below the derma at the external entrance
to the canals that carry water to the flagellated chambers or even at
the entrance to the chambers themselves[L]. Some authors object on
theoretical grounds to the statement that porocytes exist in the
Demospongia, and it is possible that these cells have in this grade
neither the same origin as, nor a precisely similar function to, the
porocytes of other sponges. When they occur in the dermal membrane no
great difficulty is experienced in seeing them under a sufficiently high
power of the microscope, if the material is well preserved and mounted
and stained in a suitable manner[M]. In most sponges the porocytes can
contract in such a way that the aperture in their centre is practically
closed, but this power appears to be possessed by the porocytes of
_Spongilla_ only to a very limited extent, although they closely
resemble the porocytes of other sponges in appearance.
[Footnote L: _Cf._ Weltner, "Spongillidenstudien, V," Arch.
Naturg. Berlin, lxxiii (i), p. 273 (1907).]
[Footnote M: It is difficult to see any trace of them in
thin microtome sections. A fragment of the membrane must be
mounted whole.]
The external membrane in many Spongillidæ is prolonged round and above
the oscula so as to form an oscular collar. This structure is highly
contractile, but cannot close together. As a rule it is much more
conspicuous in living sponges than in preserved specimens.
It is not necessary to deal here with most of the cells that
occur in the parenchyma or gelatinous part of the sponge. A full
list of the kinds that are found is given by Dr. Weltner in his
"Spongillidenstudien, V," p. 276 (Arch. Naturg. Berlin, lxxiii (i),
1907). One kind must, however, be briefly noticed as being of some
systematic importance, namely the "bubble-cells" (fig. 2 A) that are
characteristic of some species of _Ephydatia_ and other genera. These
cells are comparatively large, spherical in form; each of them contains
a globule of liquid which not only occupies the greater part of the
cell, but forces the protoplasm to assume the form of a delicate film
lining the cell-wall and covering the globule. In optical section
"bubble-cells" have a certain resemblance to porocytes, but the cell is
of course imperforate and not flattened.
SKELETON AND SPICULES.
[Illustration: Fig. 3.--Radial sections of fragments of the skeletons of
_Spongillæ_.
A, _S. crassissima_ var. _crassior_ (from Rajshahi); B, _S. carteri_
(from Calcutta); _a_=transverse, _b_=radiating fibres; _e_=external
surface of the sponge.]
In the Spongillidæ the spicules and the skeleton are more important as
regards the recognition of genera and species than the soft parts. The
skeleton is usually reticulate, but sometimes consists of a mass of
spicules almost without arrangement. The amount of spongin present is
also different in different species. The spicules in a reticulate
skeleton are arranged so as to form fibres of two kinds--radiating
fibres, which radiate outwards from the centre of the sponge and
frequently penetrate the external membrane, and transverse fibres, which
run across from one radiating fibre to another. The fibres are composed
of relatively large spicules (megascleres) arranged parallel to one
another, overlapping at the ends, and bound together by means of a more
or less profuse secretion of spongin. In some species they are actually
enclosed in a sheath of this substance. The radiating fibres are usually
more distinct and stouter than the transverse ones, which are often
represented by single spicules but are sometimes splayed out at the ends
so as to assume in outline the form of an hour-glass (fig. 3 B). The
radiating fibres frequently raise up the membrane at their free
extremities just as a tent-pole does a tent.
Normal spicules of the skeleton are always rod-like or needle-like, and
either blunt or pointed at both ends; they are either smooth, granular,
or covered with small spines. Sometimes spicules of the same type form a
more or less irregular transverse network at the base or on the surface
of the sponge.
[Illustration: Fig. 4.--Part of an oscular collar of _Spongilla
lacustris_ subsp. _reticulata_, showing arrangement of microscleres in
the derma (magnified).]
From the systematist's point of view, the structure of the free spicules
found scattered in the substance and membrane of the sponge, and
especially of those that form the armature of the gemmules, is of more
importance than that of the skeleton-spicules. Free spicules are absent
in many species; when present they are usually needle-like and pointed
at the tips. In a few species, however, they are of variable or
irregular form, or consist of several or many shafts meeting in a common
central nodule. In one genus (_Corvospongilla_) they resemble a double
grappling-iron in form, having a circle of strongly recurved hooks at
both ends. The free microscleres, or flesh-spicules as they are often
called, are either smooth, granular, or spiny.
Gemmule-spicules, which form a characteristic feature of the
Spongillidæ, are very seldom absent when the gemmules are mature. They
are of the greatest importance in distinguishing the genera. In their
simplest form they closely resemble the free microscleres, but in
several genera they bear, either at or near one end or at or near both
ends, transverse disks which are either smooth or indented round the
edge. In one genus (_Pectispongilla_) they are provided at both ends not
with disks but with vertically parallel rows of spines resembling combs
in appearance.
The simpler spicules of the Spongillidæ are formed in single cells (see
fig. 2 E), but those of more complicated shape are produced by several
cells acting in concert. Each spicule, although it is formed mainly of
hydrated silica (opal), contains a slender organic filament running
along its main axis inside the silica. This filament, or rather the tube
in which it is contained, is often quite conspicuous, and in some
species (e. g., _Spongilla crassissima_) its termination is marked at
both ends of the megasclere by a minute conical protuberance in the
silica.
Unless sponges are alchemists and can transmute one element into
another, the material of which the spicules are made must ultimately
come from the water in which the sponges live, or the rocks or other
bodies to or near which they are attached. The amount of water that must
pass through a large specimen of such a sponge as _Spongilla carteri_ in
order that it may obtain materials for its skeleton must be enormous,
for silica is an insoluble substance. I have noticed, however, that this
sponge is particularly abundant and grows with special luxuriance in
ponds in which clothes are washed with soap, and my friend Mr. G. H.
Tipper has suggested to me that possibly the alkali contained in the
soap-suds may assist the sponge in dissolving out the silica contained
in the mud at the bottom of the ponds. The question of how the mineral
matter of the skeleton is obtained is, however, one about which we know
nothing definite.
The spongin that binds the skeleton-spicules together takes the form of
a colourless or yellowish transparent membrane, which is often
practically invisible. When very abundant it sometimes extends across
the nodes of the skeleton as a delicate veil. In some sponges it also
forms a basal membrane in contact with the object to which the sponge is
attached, and in some such cases the spongin of the radiating fibres is
in direct continuity with that of the basal membrane.
COLOUR AND ODOUR.
Most freshwater sponges have a bad odour, which is more marked in some
species than in others. This odour is not peculiar to the Spongillidæ,
for it is practically identical with that given out by the common marine
sponge _Halichondria panicea_. Its function is probably protective, but
how it is produced we do not know.
The coloration of freshwater sponges is usually dull and uniform, but
_Pectispongilla aurea_ is of the brilliant yellow indicated by its name,
while many species are of the bright green shade characteristic of
chlorophyll, the colouring matter of the leaves of plants. Many species
are brown or grey, and some are almost white.
These colours are due to one of three causes, or to a combination of
more than one of them, viz.:--(1) the inhalation of solid inorganic
particles, which are engulfed by the cells; (2) the presence in the
cells of coloured substances, solid or liquid, produced by the vital
activities of the sponge; and (3) the presence in the cells of peculiar
organized living bodies known as "green corpuscles."
Sponges living in muddy water are often nearly black. This is because
the cells of their parenchyma are gorged with very minute solid
particles of silt. If a sponge of the kind is kept in clean water for a
few days, it often becomes almost white. An interesting experiment is
easily performed to illustrate the absorption and final elimination of
solid colouring matter by placing a living sponge (small specimens of
_Spongilla carteri_ are suitable) in a glass of clean water, and
sprinkling finely powdered carmine in the water. In a few hours the
sponge will be of a bright pink colour, but if only a little carmine is
used at first and no more added, it will regain its normal greyish hue
in a few days.
The colouring matter produced by the sponge itself is of two
kinds--pigment, which is probably a waste product, and the substances
produced directly by the ingestion of food or in the process of its
digestion. When pigment is produced it takes the form of minute granules
lying in the cells of the parenchyma, the dermal membrane being as a
rule colourless. Very little is known about the pigments of freshwater
sponges, and even less about the direct products of metabolism. It is
apparently the latter, however, that give many otherwise colourless
sponges a slight pinkish or yellowish tinge directly due to the presence
in cells of the parenchyma of minute liquid globules. In one form of
_Spongilla carteri_ these globules turn of a dark brown colour if
treated with alcohol. The brilliant colour of _Pectispongilla aurea_ is
due not to solid granules but to a liquid or semi-liquid substance
contained in the cells.
The green corpuscles of the Spongillidæ are not present in all species.
There is every reason to think that they represent a stage in the
life-history of an alga, and that they enter the sponge in an active
condition (see p. 49).
A fourth cause for the coloration of freshwater sponges may be noted
briefly. It is not a normal one, but occurs commonly in certain forms
(e. g., _Spongilla alba_ var. _bengalensis_). This cause is the growth
in the canals and substance of the sponge of parasitic algaæ, which turn
the whole organism of a dull green colour. They do not do so, however,
until they have reduced it to a dying state. The commonest parasite of
the kind is a filamentous species particularly common in brackish water
in the Ganges delta.
EXTERNAL FORM AND CONSISTENCY.
[Illustration: Fig. 5.--Part of a type-specimen of _Spongilla lacustris_
subsp. _reticulata_ (nat. size).]
The external form of sponges is very variable, but each species,
subspecies, or variety of the Spongillidæ has normally a characteristic
appearance. The European race of _Spongilla lacustris_, for example,
consists in favourable circumstances of a flattened basal part from
which long cylindrical branches grow out; while in the Indian race of
the species these branches are flattened instead of being cylindrical,
and anastomose freely. The structure of the branches is identical with
that of the basal part. Many other species (for instance, _Spongilla
bombayensis_ and _S. ultima_) never produce branches but always consist
of lichenoid or cushion-shaped masses. The appearance of _Spongilla
crateriformis_, when it is growing on a flattened surface which allows
it to develop its natural form, is very characteristic, for it consists
of little flattened masses that seem to be running out towards one
another, just as though the sponge had been dropped, spoonful by
spoonful, in a viscous condition from a teaspoon. Some species, such as
_Trochospongilla phillottiana_, cover large areas with a thin film of
uniform thickness, while others (e. g., _Spongilla alba_ and _Ephydatia
meyeni_) consist of irregular masses, the surface of which bears
numerous irregular ridges or conical, subquadrate, or digitate
processes. In a few forms (e. g., _Corvospongilla burmanica_) the
surface is covered with small turret-like projections of considerable
regularity, and some (e. g., _Spongilla crassissima_) naturally assume a
spherical or oval shape with an absolutely smooth surface.
The production of long branches is apparently rare in tropical
freshwater sponges.
The form of the oscula is characteristic in many cases. No other Indian
species has them so large, or with such well-defined margins as
_Spongilla carteri_ (Pl. II, fig. 1). In many species (Pl. II, fig. 3)
they have a stellate appearance owing to the fact that grooves in the
substance of the sponge radiate round them beneath the external
membrane. In other species they are quite inconspicuous and very small.
[Illustration: Fig. 6.--Radial section through part of a dried sponge of
_Spongilla crassissima_ (from Calcutta), × 5.]
Spongillidæ differ greatly in consistency. _Spongilla crassissima_ and
_Corvospongilla lapidosa_ are almost stony, although the former is
extremely light, more like pumice than true stone. Other species (e. g.,
_Trochospongilla latouchiana_) are hard but brittle, while others again
are soft and easily compressed, as _Spongilla lacustris_, the variety
_mollis_ of _S. carteri_, and _S. crateriformis_. The consistency of a
sponge depends on two factors--the number of spicules present, and the
amount of spongin. In _Corvospongilla lapidosa_ the number of spicules
is very large indeed. They are not arranged so as to form a reticulate
skeleton but interlock in all directions, and there is hardly any
spongin associated with them. In _Spongilla crassissima_, on the other
hand, the number of spicules although large is not unusually so; but
they form a very definitely reticulate skeleton, and are bound together
by an unusually profuse secretion of spongin. In _S. carteri_ var.
_mollis_ both spicules and spongin are reduced to a minimum, and the
parenchyma is relatively more bulky than usual.
VARIATION.
Sponges are very variable organisms, and even a slight change in the
environment of the freshwater species often produces a considerable
change in form and structure. Some species vary in accordance with the
season, and others without apparent cause. Not only have many given rise
to subspecies and "varieties" that possess a certain stability, but most
if not all are liable to smaller changes that apparently affect both the
individual and the breed, at any rate for a period.
(a) _Seasonal Variation._
Weltner has shown in a recent paper (Arch. Natg. Berlin, lxxiii (i), p.
276, 1907) that in Europe those individuals of _Ephydatia_ which are
found (exceptionally) in an active condition in winter differ
considerably both as regards the number of their cells and their anatomy
from those found in summer. In Calcutta the majority of the individuals
of _Spongilla carteri_ that are found in summer have their external
surface unusually smooth and rounded, and contain in their parenchyma
numerous cells the protoplasm of which is gorged with liquid. These
cells give the whole sponge a faint pinkish tinge during life; but if it
is plunged in spirit, both the liquid in the cells and the spirit turn
rapidly of a dark brown colour. Specimens of _Spongilla crateriformis_
taken in a certain tank in Calcutta during the cold weather had the
majority of the skeleton-spicules blunt, while the extremities of the
gemmule-spicules were distinctly differentiated. Specimens of the same
species taken from the same tank in July had the skeleton-spicules
pointed, while the extremities of the gemmule-spicules were much less
clearly differentiated. I have been unable to confirm this by
observations made on sponges from other tanks, but it would certainly
suggest that at any rate the breed of sponges in the tank first
investigated was liable to seasonal variation.
(b) _Variation due directly to Environment._
The characteristic external form of freshwater sponges is liable in most
cases to be altered as a direct result of changes in the environment.
The following are two characteristic instances of this phenomenon.
Certain shrubs with slender stems grow in the water at the edge of
Igatpuri Lake. The stems of these shrubs support many large examples of
_Spongilla carteri_, which are kept in almost constant motion owing to
the action of the wind on those parts of the shrubs that are not under
water. The surface of the sponges is so affected by the currents of
water thus set up against it that it is covered with deep grooves and
high irregular ridges like cockscombs. Less than a hundred yards from
the lake there is a small pond in which _Spongilla carteri_ is also
abundant. Here it grows on stones at the bottom and has the
characteristic and almost smooth form of the species.
My second instance also refers in part to Igatpuri Lake. _Corvospongilla
lapidosa_ is common in the lake on the lower surface of stones, and also
occurs at Nasik, about thirty miles away, on the walls of a conduit of
dirty water. In the latter situation it has the form of large sheets of
a blackish colour, with the surface corrugated and the oscula
inconspicuous, while in the clear waters of the lake it is of a pale
yellowish colour, occurs in small lichenoid patches, and has its oscula
rendered conspicuous, in spite of their minute size, by being raised on
little conical eminences in such a way that they resemble the craters of
volcanoes in miniature.
Both the European and the Indian races of _Spongilla lacustris_ fail to
develop branches if growing in unfavourable conditions. In specimens
obtained from the River Spree near Berlin these structures are sometimes
many inches in length; while in mature specimens taken under stones in
Loch Baa in the Island of Mull the whole organism consisted of a minute
cushion-shaped mass less than an inch in diameter, and was also
deficient in spicules. Both these breeds belong to the same species, and
probably differ as a direct result of differences in environment.
(c) _Variation without apparent cause._
Plate I in this volume illustrates an excellent example of variation in
external form to which it is impossible to assign a cause with any
degree of confidence. The three specimens figured were all taken in the
same pond, and at the same season, but in different years. It is
possible that the change in form, which was not peculiar to a few
individuals but to all those in several adjacent ponds, was due to a
difference in the salinity of the water brought about by a more or less
abundant rainfall; but of this I have been able to obtain no evidence in
succeeding years.
Many Spongillidæ vary without apparent cause as regards the shape, size,
and proportions of their spicules. This is the case as regards most
species of _Euspongilla_ and _Ephydatia_, and is a fact to which careful
consideration has to be given in separating the species.
NUTRITION.
Very little is known about the natural food of freshwater sponges,
except that it must be of an organic nature and must be either in a very
finely divided or in a liquid condition. The cells of the sponge seem to
have the power of selecting suitable food from the water that flows past
them, and it is known that they will absorb milk. The fact that they
engulf minute particles of silt does not prove that they lack the power
of selection, for extraneous matter is taken up by them not only as food
but in order that it may be eliminated. Silt would soon block up the
canals and so put a stop to the vital activity of the sponge, if it were
not got rid of, and presumably it is only taken into the cells in order
that they may pass it on and finally disgorge it in such a way or in
such a position that it may be carried out of the oscula. The siliceous
part of it may be used in forming spicules.
It is generally believed that the green corpuscles play an important
part in the nutrition of those sponges in which they occur, and there
can be no doubt that these bodies have the power peculiar to all
organisms that produce chlorophyll of obtaining nutritive substances
direct from water and carbonic oxide through the action of sunlight.
Possibly they hand on some of the nourishment thus obtained to the
sponges in which they live, or benefit them by the free oxygen given out
in the process, but many Spongillidæ do well without them, even when
living in identical conditions with species in which they abound.
REPRODUCTION.
Both eggs and buds are produced by freshwater sponges (the latter rarely
except by one species), while their gemmules attain an elaboration of
structure not observed in any other family of sponges.
Probably all Spongillidæ are potentially monoecious, that is to say,
able to produce both eggs and spermatozoa. In one Indian species,
however, in which budding is unusually common (viz. _Spongilla
proliferens_), sexual reproduction takes place very seldom, if ever. It
is not known whether the eggs of sponges are fertilized by spermatozoa
from the individual that produces the egg or by those of other
individuals, but not improbably both methods of fertilization occur.
The egg of a freshwater sponge does not differ materially from that of
other animals. When mature it is a relatively large spherical cell
containing abundant food-material and situated in some natural cavity of
the sponge. In the earlier stages of its growth, however, it exhibits
amoeboid movements, and makes its way through the common jelly. As it
approaches maturity it is surrounded by other cells which contain
granules of food-material. The food-material is apparently transferred
by them in a slightly altered form to the egg. The egg has no shell, but
in some species (e. g. _Ephydatia blembingia_[N]) it is surrounded,
after fertilization, by gland-cells belonging to the parent sponge,
which secrete round it a membrane of spongin. Development goes on within
the chamber thus formed until the larva is ready to assume a free life.
[Footnote N: Rec. Ind. Mus. i, p. 269 (1907).]
The spermatozoon is also like that of other animals, consisting of a
rounded head and a lash-like tail, the movements of which enable it to
move rapidly through the water. Spermatozoa are produced in _Spongilla_
from spherical cells not unlike the eggs in general appearance. The
contents of these cells divide and subdivide in such a way that they
finally consist of a mass of spermatozoa surrounded by a single covering
cell, which they finally rupture, and so escape.
[Illustration: Fig. 7.--Diagram of a vertical section through the
gemmule of _Spongilla proliferens_.
A=cellular contents; B=internal chitinous layer; C=external chitinous
layer; D=pneumatic coat; E=gemmule-spicule; F=external membrane;
G=foraminal tubule.]
Gemmules are asexual reproductive bodies peculiar to the sponges, but
not to the Spongillidæ. They resemble the statoblasts of the
phylactolæmatous polyzoa in general structure as well as in function,
which is mainly that of preserving the race from destruction by such
agencies as drought, starvation, and temperatures that are either too
high or too low for its activities. This function they are enabled to
perform by the facts that they are provided with coverings not only very
hard but also fitted to resist the unfavourable agencies to which the
gemmules are likely to be exposed, and that they contain abundant
food-material of which use can be made as soon as favourable conditions
occur again.
Internally the gemmule consists of a mass of cells containing
food-material in what may be called a tabloid form, for it consists of
minutely granular plate-like bodies. These cells are enclosed in a
flask-like receptacle, the walls of which consist of two chitinous
layers, a delicate inner membrane and an outer one of considerable
stoutness. The mouth of the flask is closed by an extension of the inner
membrane, and in some species is surrounded by a tubular extension of
the external membrane known as the foraminal tubule. Externally the
gemmule is usually covered by what is called a "pneumatic coat," also of
"chitin" (spongin), but usually of great relative thickness and
honeycombed by spaces which contain air, rendering the structure
buoyant. The pneumatic coat also contains the microscleres
characteristic of the species; it is often limited externally by a third
chitinous membrane, on which more gemmule-spicules sometimes lie
parallel to the surface.
The cells from which those of the gemmules are derived are akin in
origin to those that give rise to eggs and spermatozoa. Some zoologists
are therefore of the opinion that the development of the gemmule is an
instance of parthenogenesis--that is to say of an organism arising from
an egg that has not been fertilized. But some of the collar-cells,
although most of them originate from the external ciliated cells of the
larva, have a similar origin. The building-up of the gemmule affords an
excellent instance of the active co-operation that exists between the
cells of sponges, and of their mobility, for the food-material that has
to be stored up is brought by cells from all parts of the sponge, and
these cells retire after discharging their load into those of the young
gemmule.
The formation of the gemmule of _Ephydatia blembingia_, a Malayan
species not yet found in India, is described in detail by Dr. R. Evans
(Q. J. Microsc. Sci. London, xliv, p. 81, 1901).
Gemmules are produced by the freshwater sponges of Europe, N. America
and Japan at the approach of winter, but in the tropical parts of India
they are formed more frequently at the approach of the hot weather (p.
4). After they are fully formed the sponge that has produced them dies,
and as a rule disintegrates more or less completely. In some species,
however, the greater part of the skeleton remains intact, if it is not
disturbed, and retains some of the gemmules in its meshwork, where they
finally germinate. Other gemmules are set free. Some of them float on
the surface of the water; others sink to the bottom. In any case all of
them undergo a period of quiescence before germinating. It has been
found that they can be kept dry for two years without dying.
The function of the special spicules with which the gemmules of the
Spongillidæ are provided appears to be not only to protect them but more
especially to weight them to the extent suitable to the habits of each
species. Species that inhabit running water, for example, in some cases
have heavier gemmule-spicules than those that live in stagnant water,
and their gemmules are the less easily carried away by the currents of
the river. The gemmules of sponges growing in lakes are sometimes
deficient in spicules. This is the case as regards the form of
_Spongilla lacustris_ found in Lake Baa, Isle of Mull, as regards _S.
helvetica_ from the Lake of Geneva, _S. moorei_ from Lake Tanganyika,
and _S. coggini_ from Tali-Fu in Yunnan; also as regards the species of
_Spongilla_ and _Ephydatia_ found in Lake Baikal, many of the sponges of
which are said never to produce gemmules.
Except in the genus _Corvospongilla_ and the subgenus _Stratospongilla_,
in both of which the air-spaces of the gemmules are usually no more than
cavities between different chitinous membranes, the pneumatic coat is
either "granular" or "cellular." Neither of these terms, however, must
be understood in a physiological sense, for what appear to be granules
in a granular coat are actually minute bubbles of air contained in
little cavities in a foam-like mass of chitin (or rather spongin), while
the cells in a cellular one are only larger and more regular air-spaces
with thin polygonal walls and flat horizontal partitions. The walls of
these spaces are said in some cases to contain a considerable amount of
silica.
The gemmules with their various coverings are usually spherical in
shape, but in some species they are oval or depressed in outline. They
lie as a rule free in the substance of the sponge, but in some species
adhere at its base to the object to which it is attached. In some
species they are joined together in groups, but in most they are quite
free one from another.
Reproductive buds[O] are produced, so far as is known, by very few
Spongillidæ, although they are common enough in some other groups of
sponges. In the only freshwater species in which they have been found to
form a habitual means of reproduction, namely in _Spongilla
proliferens_, they have much the appearance of abortive branches, and it
is possible that they have been overlooked for this reason in other
species, for they were noticed by Laurent in _Spongilla lacustris_ as
long ago as 1840 (CR. Sé. Acad. Sci. Paris, xi, p. 478). The buds
noticed by Laurent, however, were only produced by very young sponges,
and were of a different nature from those of _S. proliferens_, perhaps
representing a form of fission rather than true budding (see 'Voyage de
la Bonite: Zoophytologie,' Spongiaires, pl. i (Paris, 1844)).
[Footnote O: Proliferation whereby more than one osculum is
produced is really a form of budding, but in most sponges
this has become no longer a mode of reproduction but the
normal method by which size is increased, and must therefore
be considered merely as a vegetative process.]
In _Spongilla proliferens_, a common Indian species, the buds arise as
thickenings of the strands of cells accompanying the radiating
spicule-fibres of the skeleton, which project outwards from the surface
of the sponge. The thickenings originate beneath the surface and
contain, at the earliest stage at which I have as yet examined them, all
the elements of the adult organism (_i. e._ flesh-spicules, ciliated
chambers, efferent and afferent canals, parenchyma-cells of various
sorts) except skeleton fibres, gemmules, and a dermal membrane. A
section at this period closely resembles one of an adult sponge, except
that the structure is more compact, the parenchyma being relatively
bulky and the canals of small diameter.
Laurent observed reproduction by splitting in young individuals of
_Spongilla_, but I have not been able to obtain evidence myself that
this method of reproduction occurs normally in Indian species. In
injured specimens of _Spongilla carteri_, however, I have observed a
phenomenon that seems to be rather an abnormal form of budding, little
rounded masses of cells making their way to the ends of the radiating
skeleton fibres and becoming transformed into young sponges, which break
loose and so start an independent existence. Possibly the buds observed
by Laurent in _S. lacustris_ were of a similar nature.
DEVELOPMENT.
(a) _From the Egg._
After fertilization, the egg, lying in its cavity in the sponge,
undergoes a complete segmentation; that is to say, becomes divided into
a number of cells without any residuum remaining. The segmentation,
however, is not equal, for it results in the formation of cells of two
distinct types, one larger and less numerous than the other. As the
process continues a pear-shaped body is produced, solid at the broader
end, which consists of the larger cells, but hollow at the other.
Further changes result in the whole of the external surface becoming
ciliated or covered with fine protoplasmic lashes, each of which arises
from a single small cell; considerable differentiation now takes place
among the cells, and spicules begin to appear. At this stage or earlier
(for there seem to be differences in different species and individuals
as to the stage at which the young sponge escapes) the larva makes its
way out of the parent sponge. After a brief period of free life, in
which it swims rapidly through the water by means of its cilia, it fixes
itself by the broad end to some solid object (from which it can never
move again) and undergoes a final metamorphosis. During this process the
ciliated cells of the external layer make their way, either by a
folding-in of the whole layer or in groups of cells, into the interior,
there change into collar-cells and arrange themselves in special
cavities--the ciliated chambers of the adult. Finally an osculum, pores,
&c., are formed, and the sponge is complete.
This, of course, is the merest outline of what occurs; other changes
that take place during the metamorphosis are of great theoretical
interest, but cannot be discussed here. The student may refer to Dr. R.
Evans's account of the larval development of _Spongilla lacustris_ in
the Q. J. Microsc. Sci. London, xlii, p. 363 (1899).
(b) _From the Gemmule._
The period for which the gemmule lies dormant probably depends to some
extent upon environment and to some extent on the species to which it
belongs. Carter found that if he cleaned gemmules with a handkerchief
and placed them in water exposed to sunlight, they germinated in a few
days; but in Calcutta gemmules of _Spongilla alba_ var. _bengalensis_
treated in this way and placed in my aquarium at the beginning of the
hot weather, did not germinate until well on in the "rains." Even then,
after about five months, only a few of them did so. Zykoff found that in
Europe gemmules kept for two years were still alive and able to
germinate.
Germination consists in the cellular contents of the gemmule bursting
the membrane or membranes in which they are enclosed, and making their
way out of the gemmule in the form of a delicate whitish mass, which
sometimes issues through the natural aperture in the outer chitinous
coat and sometimes through an actual rent in this coat. In the latter
case the development of the young sponge is more advanced than in the
former.
The fullest account of development from the gemmule as yet published is
by Zykoff, and refers to _Ephydatia_ in Europe (Biol. Centralbl. Berlin,
xii, p. 713, 1892).
His investigations show that the bursting of the gemmule is not merely a
mechanical effect of moisture or any such agency but is due to
development of the cellular contents, which at the time they escape have
at least undergone differentiation into two layers. Of the more
important soft structures in the sponge the osculum is the first to
appear, the ciliated chambers being formed later. This is the opposite
of what occurs in the case of the bud, but in both cases the aperture
appears to be produced by the pressure of water in the organism. The
manner and order in which the different kinds of cells originate in the
sponge derived from a gemmule give support to the view that the
primitive cell-layers on which morphologists lay great stress are not of
any great importance so far as sponges are concerned.
(c) _Development of the Bud._
As the bud of _Spongilla proliferens_ grows it makes its way up the
skeleton-fibre to which it was originally attached, pushing the dermal
membrane, which expands with its growth, before it. The skeleton-fibre
does not, however, continue to grow in the bud, in which a number of
finer fibres make their appearance, radiating from a point approximately
at the centre of the mass. As the bud projects more and more from the
surface of the sponge the dermal membrane contracts at its base, so as
finally to separate it from its parent. Further details are given on p.
74.
HABITAT.
Mr. Edward Potts[P], writing on the freshwater sponges of North America,
says:--"These organisms have occasionally been discovered growing in
water unfit for domestic uses; but as a rule they prefer pure water, and
in my experience the finest specimens have always been found where they
are subjected to the most rapid currents." True as this is of the
Spongillidæ of temperate climates, it is hardly applicable to those of
tropical India, for in this country we find many species growing most
luxuriantly and commonly in water that would certainly be considered
unfit for domestic purposes in a country in which sanitation was treated
as a science. Some species, indeed, are only found in ponds of water
polluted by human agency, and such ponds, provided that other conditions
are favourable, are perhaps the best collecting grounds. Other
favourable conditions consist in a due mixture of light and shade, a
lack of disturbance such as that caused by cleaning out the pond, and
above all in the presence of objects suitable for the support of
sponges.
[Footnote P: P. Ac. Philad. 1887, p. 162.]
I do not know exactly why light and shade must be mixed in a habitat
favourable for the growth of sponges, for most species prefer shade, if
it be not too dense; but it is certainly the case that, with a few
exceptions, Indian Spongillidæ flourish best in water shaded at the
edges by trees and exposed to sunlight elsewhere. One of the exceptions
to this rule is the Indian race of _Spongilla lucustris_, which is found
in small pools of water in sand-dunes without a particle of shade.
Several species are only found on the lower surface of stones and roots
in circumstances which do not suggest that their position merely
protects them from mud, which, as Mr. Potts points out, is their "great
enemy." A notable instance is _Trochospongilla pennsylvanica_, which is
found hiding away from light in America and Europe as well as in India.
It is curious that it should be easy to exterminate the sponges in a
pond by cleaning it out, for one would have thought that sufficient
gemmules would have remained at the edge, or would have been brought
rapidly from elsewhere, to restock the water. Mr. Green has, however,
noted that _Spongilla carteri_ has disappeared for some years from a
small lake at Peradeniya in which it was formerly abundant, owing to the
lake having been cleaned out, and I have made similar observations on
several occasions in Calcutta.
The question of the objects to which sponges attach themselves is one
intimately connected with that of the injury done them by mud. The delta
of the Ganges is one of the muddiest districts on earth. There are no
stones or rocks in the rivers and ponds, but mud everywhere. If a sponge
settles in the mud its canals are rapidly choked, its vital processes
cease, and it dies. In this part of India, therefore, most sponges are
found fixed either to floating objects such as logs of wood, to vertical
objects such as the stems of bulrushes and other aquatic plants, or to
the tips of branches that overhang the water and become submerged during
the "rains." In Calcutta man has unwittingly come to the assistance of
the sponges, not only by digging tanks but also by building
"bathing-ghats" of brick at the edge, and constructing, with æsthetic
intentions if not results, masses of artificial concrete rocks in or
surrounding the water. There are at least two sponges (the typical form
of _Spongilla alba_ and _Ephydatia meyeni_) which in Calcutta are only
found attached to such objects. The form of _S. alba_, however, that is
found in ponds of brackish water in the Gangetic delta has not derived
this artificial assistance from man, except in the few places where
brick bridges have been built, and attaches itself to the stem and roots
of a kind of grass that grows at the edge of brackish water. This sponge
seems to have become immune even to mud, the particles of which are
swallowed by its cells and finally got rid of without blocking up the
canals.
Several Indian sponges are only found adhering to stones and rocks.
Among these species _Corvospongilla lapidosa_ and our representatives of
the subgenus _Stratospongilla_ are noteworthy. Some forms (e. g.
_Spongilla carteri_ and _S. crateriformis_) seem, however, to be just as
much at home in muddy as in rocky localities, although they avoid the
mud itself.
There is much indirect evidence that the larvæ of freshwater sponges
exercise a power of selection as regards the objects to which they affix
themselves on settling down for life.
Few Spongillidæ are found in salt or brackish water, but _Spongilla
alba_ var. _bengalensis_ has been found in both, and is abundant in the
latter; indeed, it has not been found in pure fresh water. _Spongilla
travancorica_ has only been found in slightly brackish water, while _S.
lacustris_ subsp. _reticulata_ and _Dosilia plumosa_ occur in both fresh
and brackish water, although rarely in the latter. The Spongillidæ are
essentially a freshwater family, and those forms that are found in any
but pure fresh water must be regarded as aberrant or unusually tolerant
in their habits, not as primitive marine forms that still linger halfway
to the sea.
ANIMALS AND PLANTS COMMONLY ASSOCIATED WITH
FRESHWATER SPONGES.
(a) _Enemies._
Freshwater sponges have few living enemies. Indeed, it is difficult to
say exactly what is an enemy of a creature so loosely organized as a
sponge. There can be little doubt, in any case, that the neuropteroid
larva (_Sisyra indica_) which sucks the cells of several species should
be classed in this category, and it is noteworthy that several species
of the same genus also occur in Europe and N. America which also attack
sponges. Other animals that may be enemies are a midge larva (_Tanypus_
sp.) and certain worms that bore through the parenchyma (p. 93), but I
know of no animal that devours sponges bodily, so long as they are
uninjured. If their external membrane is destroyed, they are immediately
attacked by various little fish and also by snails of the genera
_Limnæa_ and _Planorbis_, and prawns of the genus _Palæmon_.
Their most active and obvious enemy is a plant, not an animal,--to wit,
a filamentous alga that blocks up their canals by its rapid growth (p.
79).
(b) _Beneficial Organisms._
The most abundant and possibly the most important organisms that may be
considered as benefactors to the Spongillidæ are the green corpuscles
that live in the cells of certain species (fig. 2, p. 31), notably
_Spongilla lacustris_, _S. proliferens_, and _Dosilia plumosa_. I have
already said that these bodies are in all probability algæ which live
free in the water and move actively at one stage of their existence, but
some of them are handed on directly from a sponge to its descendants in
the cells of the gemmule. In their quiescent stage they have been
studied by several zoologists, notably by Sir Ray Lankester[Q] and Dr.
W. Weltner[R], but the strongest light that has been cast on their
origin is given by the researches of Dr. F. W. Gamble and Mr. F. Keeble
(Q. J. Microsc. Sci. London, xlvii, p. 363, 1904, and li, p. 167, 1907).
These researches do not refer directly to the Spongillidæ but to a
little flat-worm that lives in the sea, _Convoluta roscoffiensis_. The
green corpuscles of this worm so closely resemble those of _Spongilla_
that we are justified in supposing a similarity of origin. It has been
shown by the authors cited that the green corpuscles of the worm are at
one stage minute free-living organisms provided at one end with four
flagella and at the other with a red pigment spot. The investigators are
of the opinion that these organisms exhibit the essential characters of
the algæ known as Chlamydomonadæ, and that after they have entered the
worm they play for it the part of an excretory system.
[Footnote Q: Q. J. Microsc. Sci. London, xxii. p. 229
(1882).]
[Footnote R: Arch. Naturg. Berlin, lix (i), p. 260 (1893).]
As they exist in the cells of _Spongilla_ the corpuscles are minute oval
bodies of a bright green colour and each containing a highly refractile
colourless granule. A considerable number may be present in a single
cell. It is found in European sponges that they lose their green colour
if the sponge is not exposed to bright sunlight. In India, however,
where the light is stronger, this is not always the case. Even when the
colour goes, the corpuscles can still be distinguished as pale images of
their green embodiment. They are called _Chlorella_ by botanists, who
have studied their life-history but have not yet discovered the full
cycle. See Beyerinck in the Botan. Zeitung for 1890 (vol. xlviii, p.
730, pl. vii; Leipzig), and for further references West's 'British
Freshwater Algæ,' p. 230 (1904).
The list of beneficent organisms less commonly present than the green
corpuscles includes a _Chironomus_ larva that builds parchment-like
tubes in the substance of _Spongilla carteri_ and so assists in
supporting the sponge, and of a peculiar little worm (_Chætogaster
spongillæ_[S]) that appears to assist in cleaning up the skeleton of the
same sponge at the approach of the hot weather and in setting free the
gemmules (p. 93).
[Footnote S: Journ. As. Soc. Beng. n. s. ii, 1906, p. 189.]
(c) _Organisms that take shelter in the Sponge or adhere to it
externally._
There are many animals which take shelter in the cavities of the sponge
without apparently assisting it in any way. Among these are the little
fish _Gobius alcockii_, which lays its eggs inside the oscula of _S.
carteri_, thus ensuring not only protection but also a proper supply of
oxygen for them (p. 94); the molluscs (_Corbula_, spp.) found inside _S.
alba_ var. _bengalensis_ (p. 78); and the Isopod (_Tachæa
spongillicola_) that makes its way into the oscula of _Spongilla
carteri_ and _S. crateriformis_ (pp. 86, 94).
In Europe a peculiar ciliated Protozoon (_Trichodina spongillæ_) is
found attached to the external surface of freshwater sponges. I have
noticed a similar species at Igatpuri on _Spongilla crateriformis_, but
it has not yet been identified. It probably has no effect, good or bad,
on the sponge.
FRESHWATER SPONGES IN RELATION TO MAN.
In dealing with _Spongilla carteri_ I have suggested that sponges may be
of some hygienic importance in absorbing putrid organic matter from
water used both for ablutionary and for drinking purposes, as is so
commonly the case with regard to ponds in India. Their bad odour has
caused some species of Spongillidæ to be regarded as capable of
polluting water, but a mere bad odour does not necessarily imply that
they are insanitary.
Unless my suggestion that sponges purify water used for drinking
purposes by absorbing putrid matter should prove to be supported by
fact, the Spongillidæ cannot be said to be of any practical benefit to
man. The only harm that has been imputed to them is that of polluting
water[T], of blocking up water-pipes by their growth--a very rare
occurrence,--and of causing irritation to the human skin by means of
their spicules--a still rarer one. At least one instance is, however,
reported in which men digging in a place where a pond had once been were
attacked by a troublesome rash probably due to the presence of
sponge-spicules in the earth, and students of the freshwater sponges
should be careful not to rub their eyes after handling dried specimens.
[Footnote T: See Potts, Proc. Ac. Philad. 1884, p. 28.]
INDIAN SPONGILLIDÆ COMPARED WITH THOSE OF OTHER COUNTRIES.
In Weltner's catalogue of the freshwater sponges (1895) seventy-six
recent species of Spongillidæ (excluding _Lubosmirskia_) are enumerated,
and the number now known is well over a hundred. In India we have
twenty-nine species, subspecies, and varieties, while from the whole of
Europe only about a dozen are known. In the neighbourhood of Calcutta
nine species, representing three genera and a subgenus, have been found;
all of them occur in the Museum tank. The only other region of similar
extent that can compare with India as regards the richness of its
freshwater sponge fauna is that of the Amazon, from which about twenty
species are known. From the whole of North America, which has probably
been better explored than any other continent so far as Spongillidæ are
concerned, only twenty-seven or twenty-eight species have been recorded.
The Indian species fall into seven genera, one of which (_Spongilla_)
consists of three subgenera. With one exception (that of
_Pectispongilla_, which has only been found in Southern India) these
genera have a wide distribution over the earth's surface, and this is
also the case as regards the subgenera of Spongilla. Four genera
(_Heteromeyenia_, _Acalle_, _Parmula_, and _Uruguaya_) that have not yet
been found in India are known to exist elsewhere.
Five of the Indian species are known to occur in Europe, viz.,
_Spongilla lacustris_, _S. crateriformis_, _S. carteri_, _S. fragilis_,
_Trochospongilla pennsylvanica_; while _Ephydatia meyeni_ is
intermediate between the two commonest representatives of its genus in
the Holarctic Zone, _Ephydatia fluviatilis_ and _E. mülleri_. Of the
species that occur both in India and in Europe, two (_Spongilla
lacustris_ and _S. fragilis_) are found in this country in forms
sufficiently distinct to be regarded as subspecies or local races.
Perhaps this course should also be taken as regards the Indian forms of
_S. carteri_, of which, however, the commonest of the Indian races would
be the typical one; but _S. crateriformis_ and _T. pennsylvanica_ seem
to preserve their specific characters free from modification, whether
they are found in Europe, Asia, or America.
The freshwater sponges of Africa have been comparatively little studied,
but two Indian species have been discovered, _S. bombayensis_ in Natal
and _S. alba_ var. _cerebellata_ in Egypt. Several of the species from
the Malabar Zone are, moreover, closely allied to African forms (p. 11).
FOSSIL SPONGILLIDÆ.
The Spongillidæ are an ancient family. Young described a species
(_Spongilla purbeckensis_) from the Upper Jurassic of Dorset (Geol. Mag.
London (new series) v, p. 220 (1878)), while spicules, assigned by
Ehrenberg to various genera but actually those of _Spongilla lacustris_
or allied forms, have been found in the Miocene of Bohemia (see
Ehrenberg's 'Atlas für Micro-Geologie,' pl. xi (Leipzig, 1854), and
Traxler in Földt. Közl., Budapest, 1895, p. 211). _Ephydatia_ is also
known in a fossil condition, but is probably less ancient than
_Spongilla_.
Ehrenberg found many sponge spicules in earth from various parts of the
Indian Empire (including Baluchistan, Mangalore, Calcutta, the Nicobars
and Nepal) and elsewhere, and it might be possible to guess at the
identity of some of the more conspicuous species figured in his 'Atlas.'
The identification of sponges from isolated spicules is, however, always
a matter of doubt, and in some cases Ehrenberg probably assigned
spicules belonging to entirely different families or even orders to the
same genus, while he frequently attributed the different spicules of the
same species to different genera. Among his fossil (or supposed fossil)
genera that may be assigned to the Spongillidæ wholly or in part are
_Aphidiscus_, _Spongolithis_, _Lithastericus_ and _Lithosphæridium_,
many of the species of these "genera" certainly belonging to _Spongilla_
and _Ephydatia_.
ORIENTAL SPONGILLIDÆ NOT YET FOUND IN INDIA.
Few freshwater sponges that have not been found in India are as yet
known from the Oriental Region, and there is positive as well as
negative evidence that Spongillidæ are less abundant in Malaysia than in
this country. The following list includes the names of those that have
been found, with notes regarding each species. It is quite possible that
any one of them may be found at any time within the geographical
boundaries laid down for this 'Fauna.' I have examined types or co-types
in all cases except that of _Ephydatia fortis_, Weltner.
I. _Spongilla_ (_Euspongilla_) _microsclerifera_*, Annandale
(Philippines). P. U.S. Mus. xxxvii, p. 131 (1909).
This sponge is closely related to _S. lacustris_, but apparently does
not produce branches. It is remarkable for the enormous number of
microscleres in its parenchyma.
II. _S._ (_Euspongilla_) _philippinensis_*, Annandale (Philippines). P.
U.S. Mus. xxxvi, p. 629 (1909).
Related to _S. alba_ and still more closely to _S. sceptrioides_ of
Australia. From the former it is readily distinguished by having
minutely spined megascleres, green corpuscles, slender gemmule-spicules
with short spines and no free microscleres.
III. _S._ (? _Euspongilla_) _yunnanensis_*, Annandale (W. China). Rec.
Ind. Mus. v, p. 197 (1910).
Apparently allied to _S. philippinensis_ but with smooth
skeleton-spicules and a more delicate skeleton.
IV. _S._ (_Stratospongilla_) _sinensis_*, Annandale (Foochow, China). P.
U.S. Mus. xxxviii, p. 183 (1910).
This species and _S. clementis_ are referred to _Stratospongilla_ with
some doubt. Their gemmules are intermediate in structure between those
of that subgenus and those of _Euspongilla_. In _S. sinensis_ the
gemmules are packed together in groups at the base of the sponge, and
their spicules are smooth, stout, and gradually pointed.
V. _S._ (_Stratospongilla_) _clementis_*, Annandale (Philippines). P.
U.S. Mus. xxxvi, p. 631 (1909).
The gemmules are single and closely adherent at the base of the sponge.
Their spicules are very slender and minutely spined.
VI. _S._ (? _Stratospongilla_) _coggini_*, Annandale (W. China). Rec.
Ind. Mus. v, p. 198 (1910).
The gemmules apparently lack microscleres. They resemble those of _S.
clementis_, to which the species is probably related, in other respects.
The skeleton-spicules are spiny and rather stout, the species being
strongly developed at the two ends.
VII. _S._ (_Stratospongilla_) _sumatrana_*, Weber (Malay Archipelago).
Zool. Ergebnisse einer Reise in Niederländisch Ost-Indien, i. p. 38
(1890).
Closely allied to _S. indica_ (p. 100) but with pointed
skeleton-spicules.
VIII. _Ephydatia fortis_, Weltner (Philippines). Arch. Naturgesch.
lxi(i), p. 141 (1895).
This species is remarkable for the great development of the spines on
the shaft of the gemmule-spicules.
IX. _Ephydatia bogorensis_*, Weber (Malay Archipelago). Zool. Ergebnisse
einer Reise in Niederländisch Ost-Indien, i, p. 33 (1890).
The gemmule-spicules have rather narrow flattish disks, the edge of
which is feebly but closely serrated.
X. _E. blembingia_*, Evans (Malay Peninsula). Q. J. Microsc. Sci.
London, xliv, p. 81 (1901).
The gemmules resemble those of _Dosilia plumosa_ but are spherical.
There are no free microscleres.
XI. _Tubella vesparium_*, v. Martens (Borneo). Arch. Naturg.
Berlin, xxxiv, p. 62 (1868).
Closely related to _T. vesparioides_ (p. 189), but with spiny
megascleres.
As regards _Spongilla decipiens_*, Weber, from the Malay Archipelago,
see p. 97.
II.
HISTORY OF THE STUDY OF FRESHWATER SPONGES.
The bath-sponge was known to the Greeks at an early date, and Homer
refers to it as being used for cleansing furniture, for expunging
writing, and for ablutionary purposes. He also mentions its peculiar
structure, "with many holes." "Many things besides," wrote the English
naturalist Ray in his 'Historia Plantarum' (1686), "regarding the powers
and uses of sponges have the Ancients: to them refer." Ray himself
describes at least one freshwater species, which had been found in an
English river, and refers to what may be another as having been brought
from America. In the eighteenth century Linné, Pallas and other authors
described the commoner European Spongillidæ in general terms, sometimes
as plants and sometimes as animals, more usually as zoophytes or
"plant-animals" partaking of the nature of both kingdoms. The gemmules
were noted and referred to as seeds. The early naturalists of the
Linnæan Epoch, however, added little to the general knowledge of the
Spongillidæ, being occupied with theory in which theological disputes
were involved rather than actual observation, and, notwithstanding the
fact that the animal nature of sponges was clearly demonstrated by
Ellis[U] in 1765, it was not until the nineteenth century was well
advanced that zoologists could regard sponges in anything like an
impartial manner.
[Footnote U: Phil. Trans. Roy. Soc. lv, p. 280.]
One of the pioneers in the scientific study of the freshwater forms was
the late Dr. H. J. Carter, who commenced his investigations, and carried
out a great part of them, in Bombay with little of the apparatus now
considered necessary, and with a microscope that must have been grossly
defective according to modern ideas. His long series of papers
(1848-1887) published in the 'Annals and Magazine of Natural History' is
an enduring monument to Indian zoology, and forms the best possible
introduction to the study of the Spongillidæ. Even his earlier mistakes
are instructive, for they are due not so much to actual errors in
observation as to a faithful transcription of what was observed with
faulty apparatus.
Contemporary with Carter were two authors whose monographs on the
freshwater sponges did much to advance the study of the group, namely,
J. S. Bowerbank, whose account of the species known at the time was
published in the 'Proceedings of the Zoological Society of London' in
1882, and the veteran American naturalist Mr. Edward Potts, whose study
of the freshwater sponges culminated in his monograph published in the
'Proceedings of the Academy of Natural Sciences of Philadelphia' in
1887. Carter's own revision of the group was published in the 'Annals
and Magazine of Natural History' in 1881. The names of Vejdovsky, who
prefaced Potts's monograph with an account of the European species, and
of Dybowsky, who published several important papers on classification,
should also be mentioned, while Weltner's catalogue of the known species
(1895) is of the greatest possible value to students of the group.
Many authors have dealt with the physiology, reproduction and
development of the Spongillidæ, especially in recent years; Dr. R.
Evans's description of the larva of _Spongilla lacustris_ (1899), and
his account of the development of the gemmule in _Ephydatia blembingia_
(1901), Zykoff's account of the development of the gemmule and of the
sponge from the gemmule (1892), and Weltner's observations on colour and
other points (1893, 1907), may be mentioned in particular. Laurent's
observations on development (1844), which were published in the 'Voyage
de la Bonite,' and especially the exquisite plates which accompany them,
have not received the notice they deserve, probably on account of their
method of publication.
LITERATURE.
The fullest account of the literature on the Spongillidæ as yet
published will be found in the first of Weltner's 'Spongillidenstudien'
(Archiv für Naturgeschichte, lix (i), p. 209, 1893). Unfortunately it
contains no references of later date than 1892. The following list is
not a complete bibliography, but merely a list of books and papers that
should prove of use to students of the Oriental Spongillidæ.
(a) _Works of Reference._
1863. BOWERBANK, "A Monograph of the Spongillidæ," P. Zool. Soc. London,
1863, pp. 440-472, pl. xxxviii.
1867. GRAY, J. E., "Notes on the arrangement of Sponges, with the
description of some new genera." _ibid._ 1867, pp. 492-558.
1881. CARTER, "History and classification of the known species of
_Spongilla_," Ann. Nat. Hist. (5) vii, pp. 77-107, pls. v, vi.
1883. VEJDOVSKY, "Die Süsswasserschwämme Böhmens," Abh. Kön. Böhm. Ges.
Wiss. (math.-natur. Classe), xii, pp. 1-43, pls. i-iii.
1887. VOSMAER, "Spongien (Porifera)," in Bronn's Thier-Reichs.
1887. POTTS, "Contributions towards a synopsis of the American forms of
Fresh-Water Sponges, with descriptions of those named by other authors
and from all parts of the world," P. Ac. Philad. pp. 158-279, pls.
v-xii.
1887. VEJDOVSKY, "Diagnosis of the European Spongillidæ," _ibid._ pp.
172-180.
1888. WIERZEJSKI, "Beitrag zur Kenntnis der Süsswasserschwämme," Verh.
k.-k. zool.-bot. Ges. Wien, xxxviii, pp. 529-536, pl. xii.
1891. WELTNER, in Zacharias's Die Tier- und Pflanzenwelt des
Süsswassers: I, Die Süsswasserschwämme.
1895. WELTNER, "Spongillidenstudien, III," Arch. Naturg. Berlin, lxi
(i), pp. 114-144.
1895. KORSCHELT and HEIDER, Text-book of the Embryology of
Invertebrates: English edition, prepared by E. L. Mark and W. McM.
Woodworth, Vol. I, chap. i.
1900. MINCHIN, Sponges--Phylum Porifera in Lankester's "Treatise on
Zoology," ii.
1905. KÜKENTHAL, W., Leitfaden für das Zoologische Praktikum (3rd Ed.,
Jena), 2. Kursus: Porifera, Schwämme, p. 31.
1906. SOLLAS, I. B. J., Cambridge Natural History--I. Porifera
(Sponges).
1909. WELTNER, "Spongillidæ, Süsswasserschwämme," in Brauer's "Die
Süsswasserfauna Deutschlands," Heft xix, pp. 177-190.
1910. LLOYD, An Introduction to Biology for Students in India.
(b) _Special Memoirs on Anatomy, Physiology, and Development._
1844. LAURENT, "Recherches sur l'Hydre et l'Eponge d'eau douce," Voyage
de la Bonite, ii, pp. 113-276.
1854. CARTER, "Zoosperms in _Spongilla_," Ann. Nat. Hist. (2) xiv, pp.
334-336, pl. xi, figs. 1-6.
1857. CARTER, "On the ultimate structure of _Spongilla_, and additional
notes on Freshwater Infusoria," Ann. Nat. Hist. (2) xx, pp. 21-41, pl.
i, figs. 1-11.
1859. CARTER, "On the identity in structure and composition of the
so-called 'seed-like body' of _Spongilla_ with the winter-egg of the
Bryozoa, and the presence of starch-granules in each," Ann. Nat. Hist.
(3) iii, pp. 331-343, pl. viii.
1859. LIEBERKÜHN, "Neue Beiträge zur Anatomie der Spongien," Arch. Anat.
Phys. J. Müller, pp. 374-375, 526-528.
1871. CARTER, "Discovery of the animal of the Spongiadæ confirmed," Ann.
Nat. Hist. (4) vii, p. 445.
1871. HAECKEL, "Ueber die sexuelle Fortpflanzung und das natürliche
System der Schwämme," Jenaische Zeitschr. f. Naturw. vi, pp. 643, 645.
1874. CARTER, "On the nature of the seed-like body of _Spongilla_; on
the origin of the mother-cell of the spicule; and on the presence of
spermatozoa in the _Spongida_," Ann. Nat. Hist. (4) xiv, pp. 97-111.
1874. LANKESTER, E. RAY, "The mode of occurrence of chlorophyll in
_Spongilla_," Q. J. Micr. Sci. xiv, pp. 400-401.
1875. SORBY, H., "On the Chromatological relations of _Spongilla
fluviatilis_," Q. J. Micr. Sci. xv, pp. 47-52.
1878. GANIN, "Zur Entwickelung der _Spongilla fluviatilis_," Zool. Anz.
I, pp. 195-199.
1882. CARTER, "Spermatozoa, polygonal cell-structure, and the green
colour in _Spongilla_, together with a new species," Ann. Nat. Hist. (5)
x, pp. 362-372, pl. 16.
1882. GEDDES, "Further researches on animals containing chlorophyll,"
Nature, xxv, pp. 303-305, 361-362.
1882. LANKESTER, E. RAY, "On the chlorophyll-corpuscles and amyloid
deposits of _Spongilla_ and _Hydra_," Q. J. Micr. Sci. xxii (n. s.), pp.
229-254, pl. xx.
1883. MARSHALL, W., "Einige vorläutige Bemerkungen über die Gemmulä der
Süsswasserschwämme," Zool. Anz. vi, pp. 630-634, 648-652.
1884. CARTER, "The branched and unbranched forms of the Freshwater
Sponges considered generally," Ann. Nat. Hist. (5) xiii, pp. 269-273.
1884. MARSHALL, W., "Vorläutige Bemerkungen über die
Fortpflanzungsverhältnisse von _Spongilla lacustris_," Ber. Naturf. Ges.
Leipzig,* pp. 22-29.
1884. POTTS, "Freshwater Sponges as improbable causes of the pollution
of river-water," P. Ac. Philad. pp. 28-30.
1885. SCHULZE, F. E., "Über das Verhältniss der Spongien zu den
Choanoflagellaten," SB. preuss. Akad. Wiss. Berlin, pp. 179-191.
1886. GOETTE, Untersuchungen zur Entwickelungsgeschichte von _Spongilla
fluviatilis_*, Hamburg und Leipzig (5 plates).
1886. WIERZEJSKI, "Le développement des Gemmules des Eponges d'eau douce
d'Europe," Arch. Slaves Biologie, i, pp. 26-47 (1 plate).
1887. CARTER, "On the reproductive elements of the _Spongida_," Ann.
Nat. Hist. (5) xix, pp. 350-360.
1889. MAAS, "Zur Metamorphose der Spongillalarve," Zool. Anz. xii, pp.
483-487.
1890. MAAS, "Ueber die Entwickelung des Süsswasserschwämmes," Zeitschr.
Wiss. Zool. 1, pp. 527-554, pls. xxii, xxiii.
1890. WEBER, M. et Mme. A., "Quelques nouveau cas de Symbiose," Zool.
Ergebn. einer Reise Niederländ. Ost-Indien, i, pp. 48-72, pl. v.
1892. ZYKOFF, "Die Entwicklung der Gemmulä der _Ephydatia fluviatilis_
auct.," Zool. Anz. xv, pp. 95-96.
1892. ZYKOFF, "Die Bildung der Gemmulä bei _Ephydatia Fluviatilis_," Revue
Sc. Nat. Soc. St. Pétersbourg,* pp. 342-344.
1892. ZYKOFF, "Die Entwicklung der Gemmulä bei _Ephydatia fluviatilis_
auct.," Bull. Soc. Imp. Natur. Moscou, n. s. vi, pp. 1-16, pl. i, ii.
1892. ZYKOFF, "Entwickelungsgeschichte von _Ephydatia mülleri_, Liebk.
aus den Gemmulæ," Biol. Centralbl. xii, pp. 713-716.
1893. WELTNER, "Spongillidenstudien, II," Arch. Naturg. Berlin, lix (1),
pp. 245-282, pls. viii, ix.
1899. EVANS, R., "The structure and metamorphosis of the larva of
_Spongilla lacustris_," Q. J. Micr. Sci. xlii, pp. 363-476, pls.
xxxv-xli.
1901. EVANS, R., "A description of _Ephydatia blembingia_, with an
account of the formation and structure of the gemmule," Q. J. Micr. Sci.
xliv, pp. 71-109, pls. i-iv.
1907. WELTNER, "Spongillideustudien, V.: Zur Biologie von _Ephydatia
fluviatilis_ and die Bedeutung der Amöbocyten für die Spongilliden,"
Arch. Naturg. Berlin, lxxiii (i), pp. 273-286.
1907. ANNANDALE, "The buds of _Spongilla proliferens_, Annand.," Rec.
Ind. Mus. i, pp. 267, 268.
1907. ANNANDALE, "Embryos of _Ephydatia blembingia_, Evans," _ibid._ p.
269.
1907. ANNANDALE, "The nature of the pores in _Spongilla_," _ibid._ pp.
270-271.
(c) _Descriptions of Asiatic Species[V] and of Animals associated with
them._
[Footnote V: Descriptions of Siberian sponges are not
included in these references.]
1847-1848. CARTER, "Notes on the species, structure, and animality of
the Freshwater Sponges in the tanks of Bombay (Genus _Spongilla_),"
Trans. Bombay Med. & Phys. Soc., 1847, and Ann. Nat. Hist. (2) i, pp.
303-311, 1848.
1849. CARTER, "A descriptive account of the Freshwater Sponges (Genus
_Spongilla_) in the Island of Bombay, with observations on their
structure and development," Ann. Nat. Hist. (2) iv, pp. 81-100, pls.
iii-v.
1868. MARTENS, E. VON, "Ueber einige östasiatische Süsswasserthiere,"
Arch. Naturg. Berlin, xxxiv, pp. 1-67: IV., Ein Süsswasserschwamm aus
Borneo, pp. 61-64, pl. i, fig. 1.
1881. CARTER, "On _Spongilla cinerea_," Ann. Nat. Hist. (5) vii, p. 263.
1890. WEBER, M., "Zoologische Ergebnisse einer Reise in Niederländisch
Ost-Indien," i, pp. 30-47, pl. iv.
1901. EVANS, R., "A description of _Ephydatia blembingia_, with an
account of the formation and structure of the gemmule," Q. J. Micr. Sci.
xliv, pp. 71-109, pls. i-iv.
1901. WELTNER, "Süsswasserspongien von Celebes (Spongillidenstudien,
IV.)," Arch. Naturg. Berlin, lxvii (1) (Special Number), pp. 187-204,
pls. vi, vii.
1906. ANNANDALE, "A variety of _Spongilla lacustris_ from brackish water
in Bengal," J. As. Soc. Bengal, (n. s.) ii, pp. 55-58.
1906. ANNANDALE, "Some animals found associated with _Spongilla carteri_
in Calcutta," _ibid._ pp. 187-196.
1907. WILLEY, "Freshwater Sponge and Hydra in Ceylon," Spolia Zeylanica,
iv, pp. 184-185.
1907. ANNANDALE, "On Freshwater Sponges from Calcutta and the
Himalayas," J. As. Soc. Bengal, (n. s.) iii, pp. 15-26.
1907. ANNANDALE, "Gemmules of _Trochospongilla phillottiana_, Annand.,"
Rec. Ind. Mus. i, p. 269.
1907. ANNANDALE, "Description of two new Freshwater Sponges from Eastern
Bengal, with remarks on allied forms," _ibid._ pp. 387-392.
1908. ANNANDALE, "Preliminary notice of a collection of Sponges from W.
India, with descriptions of two new species," Rec. Ind. Mus. ii, pp.
25-28.
1908. KIRKPATRICK, "Description of a new variety of _Spongilla
loricata_, Weltner," _ibid._ pp. 97-99.
1908. ANNANDALE, "Preliminary notice of a collection of Sponges from
Burma, with the description of a new species of _Tubella_," _ibid._ pp.
157-158.
1909. ANNANDALE, "Report on a small collection of Sponges from
Travancore," Rec. Ind. Mus. iii, pp. 101-104, pl. xii.
1909. NEEDHAM, "Notes on the Neuroptera in the collection of the Indian
Museum," _ibid._ pp. 206-207.
1909. ANNANDALE, "Description of a new species of _Spongilla_ from
Orissa," _ibid._ p. 275.
1909. ANNANDALE, "Beiträge zur Kenntnis der Fauna von Süd-Afrika: IX.
Freshwater Sponges," Zool. Jahrb. (Syst.) xxvii, pp. 559-568.
1909. ANNANDALE, "Report on a collection of Freshwater Sponges from
Japan," Annot. Zool. Japon, vii, pp. 105-112, pl. ii.
1909. ANNANDALE, "Freshwater Sponges in the collection of the United
States National Museum: Part I. Specimens from the Philippines and
Australia," P. U.S. Mus. xxxvi, pp. 627-632.
1909. ANNANDALE, "Freshwater Sponges collected in the Philippines by the
'Albatross' Expedition," _ibid._ xxxvii, pp. 131-132.
1909. ANNANDALE, "Freshwater Sponges in the collection of the United
States National Museum: Part II. Specimens from North and South
America," _ibid._ pp. 401-406.
1910. ANNANDALE, "Freshwater Sponges in the collection of the United
States National Museum: Part III. Description of a new species of
_Spongilla_ from China," _ibid._ xxxviii, p. 183.
1910. ANNANDALE, "Description of a new species of Sponge from Cape
Comorin," Rec. Ind. Mus. v, p. 31.
1910. STEPHENSON, "On some aquatic Oligochæte worms commensal in
_Spongilla carteri_," _ibid._ pp. 233-240.
1910. ANNANDALE, "Note on a Freshwater Sponge and Polyzoon from Ceylon,"
Spolia Zeylanica, vii. p. 63, pl. i.
GLOSSARY OF TECHNICAL TERMS USED IN PART I.
_Amphioxi_ (adj. Rod-like spicules sharp at both ends.
_amphioxous_)
_Amphistrongyli_ (adj. Rod-like spicules blunt at both ends.
_amphistrongylous_)
_Basal membrane_ A horny, structureless membrane found
at the base of some sponges.
_Birotulate_ (subst. or adj.) Spicule with a transverse disk at both
ends.
_Bubble-cells_ Spherical cells of the parenchyma the
contents of which consist of a drop of
liquid covered by a thin film of
protoplasm.
_Ciliated_ (or _flagellated_) A cavity lined with collar-cells.
_chamber_
_Collar-cell_ (_choanocyte_) Cell provided at one end with a
membranous collar and a vibratile lash
or flagellum that springs from within
the collar.
_Derma_ or _ectodermal layer_ A layer of flat cells arranged like a
pavement on the surface of the sponge.
_Exhalent_ (or _efferent_) A tubular canal through which water
_canal_ passes from a ciliated chamber towards
the osculum.
_Fibres_ (skeleton) Thread-like structures that compose the
skeleton of the sponge and are formed
(in the Spongillidæ) mainly of
overlapping spicules.
_Flesh-spicules_ Microscleres (_q. v._) that lie free in
the parenchyma and the derma.
_Foramen_ An orifice of the gemmule.
_Foraminal tubule_ A horny tube that surrounds the foramina
of some gemmules.
_Gemmule_ A mass of cells packed with food-material,
surrounded by at least one horny coat,
capable of retaining vitality in
unfavourable conditions and finally of
giving origin to a new sponge.
_Green corpuscles_ Minute green bodies found inside cells
of sponges and other animals and
representing a stage in the life-history
of an alga (_Chlorella_).
_Inhalent_ (or _afferent_) A tubular canal through which water
canal passes from the exterior towards a
ciliated chamber.
_Megascleres_ The larger spicules that (in the
Spongillidæ) form the basis of the
skeleton of the sponge.
_Microscleres_ Smaller spicules that lie free in the
substance or the derma of the sponge, or
are associated with the gemmule.
_Monaxon_ (Of spicules) having a single main axis;
(of sponges) possessing skeleton spicules
of this type.
_Osculum_ An aperture through which water is
ejected from the sponge.
_Oscular collar_ A ring-shaped membrane formed by an
extension of the derma round an osculum.
_Parenchyma_ The gelatinous part of the sponge.
_Pavement layer_ Adherent gemmules arranged close together
in a single layer at the base of a sponge.
_Pneumatic coat_ A horny or chitinous layer on the surface
of the gemmule containing air-spaces.
If these spaces are of regular form and
arrangement it is said to be _cellular_;
if they are minute and irregular it is
called _granular_.
_Pore_ A minute hole through which water is
taken into the sponge.
_Pore-cell_ (_porocyte_) A cell pierced by a pore.
_Radiating fibres_ Fibres in the skeleton of a sponge that
are vertical or radiate from its centre.
_Rotula_ A transverse disk borne by a microsclere.
_Rotulate_ (subst. or adj.) Spicule bearing one or two transverse
disks.
_Spicule_ A minute mineral body of regular and
definite shape due not to the forces of
crystallization but to the activity of
the living cell or cells in which it is
formed.
_Spongin_ The horny substance found in the skeletal
framework and the coverings of gemmules
of sponges. Structures formed of
this substance are often referred to as
_chitinous_.
_Subdermal cavity_ A cavity immediately below the derma
(_q. v._).
_Transverse fibres_ Fibres in the skeleton of a sponge that
run across between the radiating fibres.
_Tubelliform_ (of spicule) Having a straight shaft with a transverse
disk at one end and a comparatively
small knob-like projection at the other.
SYSTEMATIC LIST OF THE INDIAN SPONGILLIDÆ.
[Types, schizotypes, or cotypes have been examined in the case of all
species, &c., whose names are marked thus, *.]
Genus 1. SPONGILLA, Lamarck (1816).
Subgenus A. EUSPONGILLA, Vejdovsky (1883).
1. ? _S. lacustris_, auct. (perhaps in N.W. India).
1_a_. _S. lacustris_ subsp. _reticulata_*, Annandale (1907).
2. _S. proliferens_*, Annandale (1907).
3. _S. alba_*, Carter (1849).
3_a_. _S. alba_ var. _cerebellata_, Bowerbank (1863).
3_b_. _S. alba_ var. _bengalensis_*, Annandale (1906).
4. _S. cinerea_*, Carter (1849).
5. _S. travancorica_*, Annandale (1909).
6. _S. hemephydatia_*, Annandale (1909).
7. _S. crateriformis_* (Potts) (1882).
Subgenus B. EUNAPIUS, J. E. Gray (1867).
8_a_. _S. carteri_ var. _mollis_*, nov.
8_b_. _S. carteri_ var. _cava_*, nov.
8_c_. _S. carteri_ var. _lobosa_*, nov.
9_a_. _S. fragilis_ subsp. _calcuttana_*, nov.
9_b_. _S. fragilis_ var. _decipiens_, Weber (probably Malaysian,
not Indian).
10. _S. gemina_*, sp. nov.
11. _S. crassissima_*, Annandale (1907).
11_a_. _S. crassissima_ var. _crassior_*, Annandale (1907).
Subgenus C. STRATOSPONGILLA, Annandale (1909).
12. _S. indica_*, Annandale (1908).
13. _S. bombayensis_*, Carter (1882).
14. _S. ultima_*, Annandale (1910).
Genus 2. PECTISPONGILLA, Annandale (1909).
15. _P. aurea_*, Annandale (1909).
15_a_. _P. aurea_ var. _subspinosa_*, nov.
Genus 3. EPHYDATIA, Lamouroux (1816).
16. _E. meyeni_* (Carter) (1849).
Genus 4. DOSILIA, J. E. Gray (1867).
17. _D. plumosa_* (Carter) (1849).
Genus 5. TROCHOSPONGILLA, Vejdovsky (1883).
18. _T. latouchiana_*, Annandale (1907).
19. _T. phillottiana_*, Annandale (1907).
20. _T. pennsylvanica_* (Potts) (1882).
Genus 6. TUBELLA, Carter (1881).
21. _T. vesparioides_*, Annandale (1908).
Genus 7. CORVOSPONGILLA, nov.
22. _C. burmanica_* (Kirkpatrick) (1908).
23. _C. lapidosa_* (Annandale) (1908).
Order HALICHONDRINA.
Siliceous monaxon sponges in which the horny skeleton is much reduced or
absent and the spicular skeleton is more or less definitely reticulate.
The microscleres are usually rod-like and rarely have more than one main
axis.
Family SPONGILLIDÆ.
SPONGILLADÆ, J. E. Gray, P. Zool. Soc. London, 1867, p. 550.
Freshwater Halichondrina which at certain seasons produce gemmules armed
with peculiar microscleres. Two distinct kinds of microsclere are often
present, that associated with the gemmule sometimes consisting of a
vertical shaft at the ends of which transverse disks or rotulæ are
borne. There is always at least a trace of a subdermal cavity.
Many authors divide the Spongillidæ into two subfamilies:--Spongillinæ
(or Euspongillinæ), in which the gemmule-spicules have no transverse
rotulæ, and Meyeninæ (or Ephydatiinæ), in which they have rotules at one
or both ends. So gradual, however, is the transition that I find it
difficult to decide in one instance to which of two genera, typical
respectively of the two "subfamilies," a species should be assigned.
Minchin in his account of the Porifera in Lankester's "Treatise on
Zoology" (1900) regards the Spongillidæ merely as a subfamily of the
Heterorrhaphidæ, and there certainly are few differences of a definite
nature between them and the marine family (or subfamily) Remeridæ.
_Key to the Indian Genera of_ Spongillidæ.
I. Microscleres without transverse disks.
A. Microscleres of the parenchyma similar
in general structure to those or the
gemmule; the latter without comb-like
vertical rows of spines at the ends SPONGILLA, p. 67.
B. Microscleres of the gemmule with comb-like
vertical rows of spines at both ends PECTISPONGILLA, p. 106.
II. Some or all of the microscleres birotulate.
(Birotulate microscleres of one kind only.)
A. Microscleres of the gemmule birotulate, the
rotules with serrated or strongly sinuous
edges; parenchyma spicules usually absent,
never of complicated structure EPHYDATIA, p. 108.
B. Microscleres of the gemmule as in
_Ephydatia_; microscleres of the parenchyma
consisting of numerous shafts
meeting in different planes in a central
nodule DOSILIA, p. 110.
C. Microscleres as in _Ephydatia_ except
that the rotulæ of the gemmule-spicules
have smooth edges TROCHOSPONGILLA, p. 113.
D. Microscleres of the gemmule without a
trace of rotules, those of the parenchyma
birotulate CORVOSPONGILLA, nov., p. 122.
III. Microscleres of the gemmule with a well-developed
basal rotule and a vertical shaft
ending above in a mere knob. TUBELLA, p. 120.
The most distinct genus of Spongillidæ not yet found in India is
_Heteromeyenia_, Potts. It is easily distinguished from all others by
the fact that the birotulate spicules of the gemmule are of two quite
distinct kinds, which occur together on every mature gemmule.
_Heteromeyenia_ is represented by several American species, one of which
has been found in Europe. _Acalle_, J. E. Gray, which is represented by
a single South American species (_Spongilla recurvata_, Bowerbank), is
related to _Heteromeyenia_ but has one kind of gemmule-spicule
tubelliform, the other birotulate. Probably _Uraguaya_, Carter, should
be regarded as a subgenus of _Trochospongilla_ with an unusually solid
skeleton; it is peculiar to S. America. _Parmula_, Carter (=_Drulia_,
Gray) includes South American forms allied to _Tubella_, but with the
shaft of the gemmule-spicule degenerate and consisting of a mere
projection in the centre of a shield-like body, which represents the
lower rotule. The status of _Potamolepis_, Marshall, originally
described from the Lake of Galilee, is very doubtful; possibly some or
all of its species belong to the subgenus of _Spongilla_ here called
_Stratospongilla_ (p. 100); but they are stated never to produce
gemmules. The same is the case as regards _Pachydictyum_, Weltner, which
consists of a single species from Celebes.
The sponges from Lake Baikal assigned by Weltner (Arch. Naturg. lxi (i)
p. 131) to the subfamily Lubomirskinæ are of doubtful position and need
not be considered here; while _Lessepsia_, Keller, from one of the salt
lakes on the Suez Canal, certainly does not belong to the family,
although it is assigned to it by von Lendenfeld (Mon. Horny Sponges, p.
904 (1889)) and subsequently by Minchin (Porifera, p. 152, in
Lankester's Treatise on Zoology, part ii (1900)).
Genus 1. SPONGILLA, _Lamarck_ (Carter _emend._).
_Spongilla_, Lamarck, Histoire des Animaux sans Vertèbres, ii, p. 111
(1836).
_Spongilla_, Carter, Ann. Nat. Hist. (5) vii, p. 86 (1881).
_Euspongilla_, Vejdovsky, Abh. Böhm. Ges. xii, p. 15 (1883).
_Spongilla_, Potts, P. Ac. Philad. 1887, p. 182.
TYPE, _Spongilla lacustris_, auctorum.
Spongillidæ in which the gemmules have (normally) cylindrical or
subcylindrical spicules that are sharp or blunt at the ends, without a
distinct transverse disk or disks and without comb-like vertical rows of
spines.
The skeleton is variable in structure, sometimes being almost amorphous,
sometimes having well-defined radiating and transverse fibres firmly
compacted with spongin. The skeleton-spicules are either sharp or blunt
at the ends. Flesh-spicules are often absent; when present they are
needle-like and resemble the gemmule-spicules in general structure; they
have not even rudimentary rotules at their ends. The gemmules either lie
free in the substance of the sponge or are attached to its support;
sometimes they adhere together in free or attached groups.
_Spongilla_ is undoubtedly the most primitive genus of the Spongillidæ,
its spicules showing less sign of specialization than those of any other
genus included in the family. As a fossil it goes back at any rate to
the Upper Jurassic (p. 52).
GEOGRAPHICAL DISTRIBUTION.--Cosmopolitan. In most countries the majority
of the freshwater sponges belong to this genus, but in Japan _Ephydatia_
seems to predominate.
_Key to the Indian Species of_ Spongilla.
I. Gemmule provided with a thick, apparently
granular pneumatic coat in
which the gemmule-spicules are arranged
tangentially or vertically. (Subgenus
_Euspongilla_, p. 69.)
A. No foraminal tubule.
_a._ Sponge bright green, soft and
compressiblewhen fresh, very fragile
dry _lacustris_, p. 69.
_a'._ Sponge white or grey, hard both
fresh and dry _alba_, p. 76.
B. A foraminal tubule present.
_b._ Skeleton-spicules smooth.
beta. Gemmules free; gemmule-spicules
arranged tangentially and
horizontally _proliferens_, p. 72.
beta'. Gemmules free; gemmule-spicules
arranged vertically or nearly
so in a single series _hemephydatia_, p. 82.
beta''. Gemmules firmly fixed
to the support of the sponge;
gemmule-spicules almost vertical,
irregularly arranged, as a rule in
more than one series _travancorica_, p. 81.
_b'._ Skeleton-spicules spiny or
irregular in outline.
beta'''. Gemmule-spicules tangential
and horizontal, without
rudimentary rotules _cinerea_, p. 79.
beta''''. Gemmule-spicules vertical or
nearly so, often with
rudimentary rotules at the tips _crateriformis_, p. 83.
II. Gemmules surrounded in several layers
by distinct polygonal air-spaces with
chitinous walls. (Subgenus _Eunapius_,
p. 86.)
A. Gemmules single. Skeleton- and
gemmule-spicules smooth, pointed,
not very stout _carteri_, p. 87.
B. Gemmules bound together in pairs.
Skeleton friable; skeleton-spicules
slender _gemina_, nov., p. 97.
C. Gemmules bound together in free
groups of more than two or forming
a "pavement-layer" at the base of
the sponge.
_c._ Skeleton friable;
skeleton-spicules slender _fragilis_, p. 95.
_c'._ Skeleton very hard and
resistant; skeleton-spicules stout _crassissima_, p. 98.
III. Gemmules without or with irregular
pneumatic coat, covered by a chitinous
membrane or membranes in which the
gemmule-spicules lie parallel to the
surface. (Subgenus _Stratospongilla_,
p. 100.)
A. Skeleton spicules spiny or irregular in
outline.
_a._ Skeleton-spicules blunt; gemmules
covered by a single chitinous
membrane _indica_, p. 100.
_a'._ Skeleton-spicules sharp; gemmules
covered by two chitinous membranes _bombayensis_, p. 102.
B. Skeleton-spicules smooth.
Skeleton-spicules sharp; gemmule
spicules very irregular in form _ultima_, p. 104.
Subgenus A. EUSPONGILLA, _Vejdovsky_.
_Euspongilla_, Vejdovsky, Abh. Böhm. Ges. xii, p. 15 (1883).
_Euspongilla_, _id._, in Potts's "Fresh-Water Sponges," P. Ac. Philad.
1887, p. 172.
_Euspongilla_, Weltner, in Zacharias's Tier- und Pflanzenwelt des
Süsswassers, i, p. 210 (1891).
TYPE, _Spongilla lacustris_, auctorum.
Spongillæ in which the gemmules are covered with a thick, apparently
granular pneumatic coat. A delicate membrane often occurs outside this
coat, but it is never thick or horny. The gemmules usually lie free in
the sponge but sometimes adhere to its support; rarely they are fastened
together in groups (_e. g._ in _S. aspinosa_, Potts). The
skeleton-spicules are never very stout and the skeleton is always
delicate.
The species in this subgenus are closely allied and must be
distinguished rather by the sum of their peculiarities than by any one
character. They occur in all countries in which Spongillidæ are found.
Seven Indian species may be recognized.
1. Spongilla lacustris, _auctorum_.
_Spongilla lacustris_, Bowerbank, P. Zool. Soc. London, 1863, p. 441,
pl. xxxviii, fig. 14.
_Spongilla lacustris_, Carter, Ann. Nat. Hist. (5) vii, p. 87 (1881).
_Euspongilla lacustris_, Vejdovsky, in Potts's "Fresh-Water Sponges,"
P. Ac. Philad. 1887, p. 172.
_Spongilla lacustris_, Potts, _ibid._, p. 186, pl. v, fig. 1, pl. vii,
figs. 1-6.
_Euspongilla lacustris_, Weltner, in Zacharias's Tier- und Pflanzenwelt
des Süsswassers, i, p. 211, figs. 36-38 (1891).
_Spongilla lacustris_, _id._, Arch. Naturg. lxi (i), pp. 118, 133-135
(1895).
_Spongilla lacustris_, Annandale, J. Linn. Soc., Zool., xxx, p. 245
(1908).
[I have not attempted to give a detailed synonymy of this
common species. There is no means of telling whether many of
the earlier names given to forms or allies of _S. lacustris_
are actual synonyms, and it would serve no useful purpose,
so far as the fauna of India is concerned, to complicate
matters by referring to obscure descriptions or possible
descriptions of a species only represented in India, so far
as we know, by a specialized local race, to which separate
references are given.]
_Sponge_ soft and easily compressed, very brittle when dry, usually
consisting of a flat or rounded basal portion of no great depth and of
long free cylindrical branches, which droop when removed from the water;
branches occasionally absent. Colour bright green when the sponge is
growing in a strong light, dirty flesh-colour when it is growing in the
shade. (Even in the latter case traces of the "green corpuscles" can be
detected in the cells of the parenchyma.) Oscula star-shaped, of
moderate size, as a rule rendered conspicuous by the furrows that
radiate from them over the outer surface of the parenchyma below the
external membrane; oscular collars well developed.
_Skeleton_ reticulate, loose, with definite radiating and transverse
fibres held together by a small quantity of spongin; the fibres slender
but not extremely so.
_Spicules._ Skeleton-spicules smooth, sharply pointed, long, slender.
Flesh-spicules slender, covered with small spines, sharply pointed,
nearly straight. Gemmule-spicules resembling the flesh-spicules but
shorter and as a rule more strongly curved, sometimes bent so as to form
semicircular figures, usually pointed somewhat abruptly; their spines
relatively longer than those of the flesh-spicules, often curved
backwards, especially near the ends of the spicules, at which points
they are often longer than elsewhere.
_Gemmules_ usually numerous in autumn, lying free in the sponge,
spherical, variable in size but usually rather large, as a rule covered
with a thick granular coat in which the spicules are arranged
tangentially; a horizontal layer of spicules often present in the
external membrane; the granular coat and its spicules occasionally
deficient. No foraminal tubule; its place sometimes taken by an open,
bowl-shaped chitinous structure the base of which is in continuity with
the inner chitinous coat of the gemmule.
_S. lacustris_ is an extremely variable species, varying in the size,
proportions and shape of its spicules, in its external form and in the
size and structure of the gemmule. A considerable number of varieties
have been described from different parts of Europe and N. America, but
some of these may represent distinct but closely-allied species;
descriptions of most of them will be found in Potts's "Fresh-Water
Sponges." The embryology and the earlier stages of the development from
the egg have been described in great detail by Evans (Quart. J. Micr.
Sci. (n. s.) xlii, p. 363 (1899)), while the anatomy and physiology are
discussed by most authors who have written on these features in the
Spongillidæ.
TYPE.--It is impossible to say who was the first authority to use the
name _Spongilla lacustris_ in the sense in which it is used by recent
authors. No type can therefore be recognized.
GEOGRAPHICAL DISTRIBUTION.--_S. lacustris_ occurs all over Europe and N.
America and is probably the commonest species in most parts of both
continents. It has also been found in Northern Asia and may occur in the
Himalayan lakes and in the north-west of India.
1 _a._ Subspecies reticulata*, _Annandale_.
_Spongilla reticulata_, Annandale, Rec. Ind. Mus. i, p. 387,
pl. xiv, fig. 1 (1907).
_Spongilla lacustris_ subspecies _reticulata_, _id._, P.
U.S. Mus. xxxvii, p. 401 (1909).
This race differs from the typical _S. lacustris_ in the following
particulars:--
(1) The branches are always compressed and anastomose
freely when well developed (fig. 5, p. 37);
(2) the skeleton-fibres are finer;
(3) the skeleton-spicules are longer;
(4) the gemmule-spicules are longer and more slender and are
never strongly bent.
[Illustration: Fig. 8.
A=gemmule-spicules of _Spongilla lacustris_ subsp. _reticulata_ (from
type); B=gemmule-spicules of _S. alba_ from Calcutta: both highly
magnified.]
As regards the form of the skeleton- and gemmule-spicules and also that
of the branches the subspecies _reticulata_ resembles _S. alba_ rather
than _S. lacustris_, but owing to the fact that it agrees with _S.
lacustris_ in its profuse production of branches, in possessing green
corpuscles and in its fragility, I think it should be associated with
that species.
The branches are sometimes broad (fig. 5, p. 37), sometimes very
slender. In the latter condition they resemble blades of grass growing
in the water.
TYPE in the Indian Museum; a co-type in the British Museum.
GEOGRAPHICAL DISTRIBUTION.--All over Eastern India and Burma; also in
the Bombay Presidency. _Localities:_--BENGAL, Port Canning, Ganges
delta; Rajshahi (Rampur Bhulia) on the Ganges, 150 miles N. of Calcutta
(_Annandale_); Puri district, Orissa (_Annandale_); R. Jharai, Siripur,
Saran district, Tirhut (_M. Mackenzie_): MADRAS PRESIDENCY, Madras
(town) (_J. R. Henderson_): BOMBAY PRESIDENCY, Igatpuri, W. Ghats
(_Annandale_).
BIOLOGY.--This subspecies is usually found in small masses of water,
especially in pools of rain-water, but Mr. Mackenzie found it growing
luxuriantly in the Jharai at a time of flood in September. It is very
abundant in small pools among the sand-dunes that skirt the greater part
of the east coast of India. Here it grows with great rapidity during the
"rains," and often becomes desiccated even more rapidly as soon as the
rain ceases. As early in the autumn as October I have seen masses of the
sponge attached, perfectly dry, to grass growing in the sand near the
Sur Lake in Orissa. They were, of course, dead but preserved a life-like
appearance. Some of them measured about six inches in diameter. At Port
Canning the sponge grows during the rains on the brickwork of bridges
over ditches of brackish water that dry up at the beginning of winter,
while at Rajshahi and at Igatpuri I found it at the edges of small
ponds, at the latter place in November, at the former in February.
Specimens taken at Madras by Dr. Henderson during the rains in small
ponds in the sand contained no gemmules, but these structures are very
numerous in sponges examined in autumn or winter.
Numerous larvæ of _Sisyra indica_ (p. 92) were found in this sponge at
Rajshahi. Unlike those obtained from _S. alba_, they had a green colour
owing to the green matter sucked from the sponge in their stomachs. The
_coralloides_ phase of _Plumatella fruticosa_ (p. 219) was also found in
_S. lacustris_ subsp. _reticulata_ at Rajshahi.
So far as my experience goes, this subspecies has always a bright green
colour due to the presence of "green corpuscles," even when it is
growing in a pond heavily shaded by trees or under the arch of a small
bridge. Probably the more intense light of India enables the corpuscles
to flourish in situations in which in Europe they would lose their
chlorophyll.
2. Spongilla proliferens*, _Annandale_.
_Spongilla cinerea_, Weber (_nec_ Carter), Zool. Ergeb.
Niederl. Ost-Ind. vol. i, pp. 35, 46 (1890).
_Spongilla proliferens_, Annandale, J. Asiat. Soc. Bengal,
1907, p. 15, fig. 1.
_Spongilla proliferens_, _id._, Rec. Ind. Mus. i, pp. 267,
271 (1907).
_Sponge_ forming soft, shallow cushions rarely more than 10 cm. in
diameter on the leaves of water-plants, or small irregular masses on
their roots and stems. Colour bright green. Oscula moderate, flat,
surrounded by deep, cone-shaped collars; radiating furrows and canals in
the parenchyma surrounding them often deep. External pores contained
normally in single cells. The surface frequently covered by small
rounded buds; true branches if present more or less flattened or
conical, always short, as a rule absent.
_Skeleton_ loose, feebly reticulate at the base of the sponge;
transverse fibres slender in the upper part of the sponge, often
scarcely recognizable at its base. Very little spongin present.
_Spicules._ Skeleton-spicules long, smooth, sharply pointed; the length
on an average at least 20 times the greatest breadth, often more.
Flesh-spicules slender, gradually pointed, nearly straight, covered with
minute straight or nearly straight spines. Gemmule-spicules very
similar, but usually a little stouter and often blunt at the ends; their
spines rather longer than those on the flesh-spicules, usually more
numerous near the ends than in the middle of the spicule, slightly
retroverted, those at the extreme tips often so arranged as to suggest a
rudimentary rotule.
[Illustration: Fig. 9.--Gemmule of _Spongilla proliferens_ as seen in
optical section (from Calcutta), × 140.]
_Gemmules_ usually numerous, lying free near the base of the sponge,
very variable in size, spherical, surrounded by a thick granular layer
in which the spicules, which are always very numerous, are arranged
tangentially, their position being more near the vertical than the
horizontal; a few horizontal spicules usually present on the external
surface of the gemmule, which frequently has a ragged appearance owing
to some of the tangential spicules protruding further than others.
Foraminal tubule stout, cylindrical, usually somewhat contorted; its
orifice irregular in outline. Sometimes more than one foramen present.
_S. proliferens_ can be distinguished from all forms of _S. lacustris_
and _S. alba_ by the fact that its gemmules possess a foraminal tubule;
from _S. cinerea_ it can be distinguished by its colour and its smooth
skeleton-spicules, and from _S. travancorica_ by its free gemmules. I
have been enabled by the kindness of Prof. Max Weber to examine
specimens from Celebes and Java identified by him as _S. cinerea_,
Carter, and have no doubt that they belong to my species.
TYPE in the Indian Museum; a co-type in the British Museum.
GEOGRAPHICAL DISTRIBUTION.--All over Eastern India and Burma; also in
Cochin on the west coast; Ceylon; W. China; Java, Flores and Celebes.
_Localities_:--BENGAL, Calcutta and neighbourhood (_Annandale_);
Berhampore, Murshidabad district (_R. E. Lloyd_): ASSAM, Mangal-dai near
the Bhutan frontier (_S. W. Kemp_): MADRAS PRESIDENCY, Madras (town) and
neighbourhood (_J. R. Henderson_); Rambha, Ganjam district
(_Annandale_); Bangalore, Mysore (alt. _ca._ 3000 ft.) (_Annandale_);
Ernakulam and Trichur, Cochin (_G. Mathai_): BURMA, Rangoon
(_Annandale_, _J. Coggin Brown_); Prome, Upper Burma (_J. Coggin
Brown_); Kawkareik, Amherst district, Tenasserim (_Annandale_): CEYLON,
between Maradankawela and Galapita-Gala, North Central Province
(_Willey_). Mr. J. Coggin Brown has recently brought back specimens from
Yunnan.
BIOLOGY.--_S. proliferens_ is usually found in ponds which never dry up;
Prof. Max Weber found it in small streams in Malaysia. It is common in
India on the leaves of _Vallisneria_ and _Limnanthemum_, on the roots of
_Pistia stratiotes_ and on the stems of rushes and grass. So far as I
have been able to discover, the life of the individual sponge is short,
only lasting a few weeks.
Sexual reproduction occurs seldom or never, but reproduction by means of
buds and gemmules continues throughout the year. The former is a rare
method of reproduction in most Spongillidæ but in this species occurs
normally and constantly, the buds being often very numerous on the
external surface. They arise a short distance below the surface as
thickenings in the strands of cells that accompany the radiating fibres
of the skeleton. As they grow they push their way up the fibres, forcing
the external membrane outwards. The membrane contracts gradually round
their bases, cuts off communication between them and the parent sponge
and finally sets them adrift. No hole remains when this takes place, for
the membrane closes up both round the base of the bud and over the
aperture whence it has emerged.
The newly liberated bud already possesses numerous minute pores, but as
yet no osculum; its shape exhibits considerable variation, but the end
that was farthest from the parent-sponge before liberation is always
more or less rounded, while the other end is flat. The size also varies
considerably. Some of the buds float, others sink. Those that float do
so either owing to their shape, which depends on the degree of
development they have reached before liberation, or to the fact that a
bubble of gas is produced in their interior. The latter phenomenon only
occurs when the sun is shining on the sponge at the moment they are set
free, and is due to the action of the chlorophyll of the green bodies so
abundant in certain of the parenchyma cells of this species. If the
liberation of the bud is delayed rather longer than usual, numbers of
flesh-spicules are produced towards the ends of the primary
skeleton-fibres and spread out in one plane so as to have a fan-like
outline; in such buds the form is more flattened and the distal end less
rounded than in others, and the superficial area is relatively great, so
that they float more readily. Those buds that sink usually fall in such
a way that their proximal, flattened end comes in contact with the
bottom or some suspended object, to which it adheres. Sometimes,
however, owing to irregularity of outline in the distal end, the
proximal end is uppermost. In this case it is the distal end that
adheres. Whichever end is uppermost, it is in the uppermost end, or as
it may now be called, the upper surface, that the osculum is formed.
Water is drawn into the young sponge through the pores and, finding no
outlet, accumulates under the external membrane, the subdermal cavity
being at this stage even larger than it is in the adult sponge.
Immediately after adhesion the young sponge flattens itself out. This
process apparently presses together the water in the subdermal cavity
and causes a large part of it to accumulate at one point, which is
usually situated near the centre of the upper surface. A transparent
conical projection formed of the external membrane arises at this point,
and at the tip of the cone a white spot appears. What is the exact cause
of this spot I have not yet been able to ascertain, but it marks the
point at which the imprisoned water breaks through the expanded
membrane, thus forming the first osculum. Before the aperture is formed,
it is already possible to distinguish on the surface of the parenchyma
numerous channels radiating from the point at which the osculum will be
formed to the periphery of the young sponge. These channels as a rule
persist in the adult organism and result from the fact that the inhalent
apertures are situated at the periphery, being absent from both the
proximal and the distal ends of the bud. In the case of floating buds
the course of development is the same, except that the osculum, as in
the case of development from the gemmule in other species (see Zykoff,
Biol. Centrbl. xii, p. 713, 1892), is usually formed before adhesion
takes place.
The sponge of _S. proliferens_ is usually too small to afford shelter to
other animals, and I have not found in it any of those commonly
associated with _S. carteri_ and _S. alba_.
Owing to its small size _S. proliferens_ is more easily kept alive in an
aquarium than most species, and its production of buds can be studied in
captivity. In captivity a curious phenomenon is manifested, viz. the
production of extra oscula, often in large numbers. This is due either
to a feebleness in the currents of the sponge which makes it difficult
to get rid of waste substances or to the fact that the canals get
blocked. The effluent water collects in patches under the external
membrane instead of making its way out of the existing oscula, and new
oscula are formed over these patches in much the same way as the first
osculum is formed in the bud.
3. Spongilla alba*, _Carter_.
_Spongilla alba_, Carter, J. Bombay Asiat. Soc. iii, p. 32,
pl. i, fig. 4 & Ann. Nat. Hist. (2) iv, p. 83, pl. iii, fig.
4 (1849)
_Spongilla alba_, Bowerbank, P. Zool. Soc. London, 1863, p.
463 pl. xxxviii, fig. 15.
_Spongilla alba_, Carter, Ann. Nat. Hist. (5) vii, p. 88
(1881).
_Spongilla alba_, Petr, Rozp. Ceske Ak. Praze, Trída, ii,
pl. i, figs. 3-6 (1899) (text in Czech).
_Spongilla alba_, Annandale, Rec. Ind. Mus. i, p. 388, pl.
xiv, fig. 2 (1907).
_Sponge_ forming masses of considerable area, but never of more than
moderate depth or thickness. Surface smooth and undulating or with
irregular or conical projections; sponge hard but brittle; colour white
or whitish; oscula of moderate or large size, never very conspicuous;
radiating furrows absent or very short; external membrane adhering to
the substance of the sponge.
_Skeleton_ forming a moderately dense network of slender radiating and
transverse fibres feebly held together; little spongin present; the
meshes much smaller than in _S. lacustris_ or _S. proliferens_.
_Spicules._ Skeleton-spicules smooth, sharply pointed, slender, feebly
curved. Gemmule-spicules (fig. 8, p. 71) slender, cylindrical, blunt or
abruptly pointed at the ends, feebly curved, bearing relatively long
backwardly directed spines, which are usually more numerous at the ends
than near the middle of the shaft. Flesh-spicules very numerous in the
parenchyma and especially the external membrane, as a rule considerably
more slender and more sharply pointed than the gemmule-spicules, covered
with straight spines which are often longer at the middle of the shaft
than at the ends.
_Gemmules_ usually of large size, with a moderately thick granular
layer; spicules never very numerous, often lying horizontally on the
external surface of the gemmule as well as tangentially in the granular
layer; no foraminal tubule; a foraminal cup sometimes present.
3_a_. Var. cerebellata, _Bowerbank_.
_Spongilla cerebellata_, Bowerbank, P. Zool. Soc. London,
1863, p. 465, pl. xxxviii, fig. 16.
_Spongilla alba_ var. _cerebellata_, Carter, Ann. Nat. Hist.
(5) vii, p. 88 (1881).
_Spongilla cerebellata_, Weltner, Arch. Naturg. lxi (i), p.
117 (1895).
_Spongilla cerebellata_, Kirkpatrick, Ann. Nat. Hist. (7)
xx, p. 523 (1907).
This variety is distinguished from the typical form by the total absence
of flesh-spicules. The gemmule-spicules are also more numerous and cross
one another more regularly.
3_b_. Var. bengalensis*, _Annandale_. (Plate I, figs. 1-3.)
_Spongilla lacustris_ var. _bengalensis_, Annandale, J.
Asiat. Soc. Bengal, 1906, p. 56.
_Spongilla alba_ var. _marina_, _id._, Rec. Ind. Mus. i, p.
389 (1907).
The sponge is either devoid of branches or produces irregular,
compressed, and often digitate processes, sometimes of considerable
length and delicacy. Flesh-spicules are usually present throughout the
sponge, but are sometimes absent from one part of a specimen and present
in others. Some of the gemmules are often much smaller than the others.
Perhaps this form should be regarded as a phase rather than a true
variety (see p. 18).
All forms of _S. alba_ can be distinguished from all forms of _S.
lacustris_ by the much closer network of the skeleton and by the
consequent hardness of the sponge; also by the complete absence of green
corpuscles.
TYPES. The types of the species and of the var. _cerebellata_ are in the
British Museum, with fragments of the former in the Indian Museum; that
of var. _bengalensis_ is in the Indian Museum, with a co-type in London.
GEOGRAPHICAL DISTRIBUTION.--India And Egypt. _Localities_:--BOMBAY
PRESIDENCY, island of Bombay (_Carter_); Igatpuri, W. Ghats
(_Annandale_): BENGAL, Calcutta; Port Canning, Ganges delta (var.
_bengalensis_) (_Annandale_); Garia, Salt Lakes, nr. Calcutta (var.
_bengalensis_) (_B. L. Chaudhuri_); Chilka Lake, Orissa (var.
_bengalensis_) (_Gopal Chunder Chatterjee_): MADRAS PRESIDENCY, Rambha,
Ganjam district (_Annandale_): NIZAM'S TERRITORY, Aurangabad
(_Bowerbank_, var. _cerebellata_). The var. _cerebellata_ has also been
taken near Cairo.
BIOLOGY.--The typical form of the species is usually found growing on
rocks or bricks at the edges of ponds, while the variety _bengalensis_
abounds on grass-roots in pools and swamps of brackish water in the
Ganges delta and has been found on mussel-shells (_Modiola jenkinsi_,
Preston) in practically salt water in the Chilka Lake. Carter procured
the typical form at Bombay on stones which were only covered for six
months in the year, and "temporarily on floating objects." In Calcutta
this form flourishes in the cold weather on artificial stonework in the
"tanks" together with _S. carteri_, _S. fragilis_, _Ephydatia meyeni_,
and _Trochospongilla latouchiana_.
The variety _bengalensis_ is best known to me as it occurs in certain
ponds of brackish water at Port Canning on the Mutlah River, which
connects the Salt Lakes near Calcutta with the sea. It appears in these
ponds in great luxuriance every year at the beginning of the cold
weather and often coats the whole edge for a space of several hundred
feet, growing in irregular masses which are more or less fused together
on the roots and stems of a species of grass that flourishes in such
situations. Apparently the tendency for the sponges to form branches is
much more marked in some years than in others (see Pl. I, figs. 1-3).
The gemmules germinate towards the end of the "rains," and large masses
of sponge are not formed much before December. At this season, however,
the level of the water in the ponds sinks considerably and many of the
sponges become dry. If high winds occur, the dry sponges are broken up
and often carried for considerable distances over the flat surrounding
country. In January the gemmules floating on the surface of the ponds
form a regular scum. _S. alba_ var. _bengalensis_ is the only sponge
that occurs in these ponds at Port Canning, but _S. lacustris_, subsp.
_reticulata_, is occasionally found with it on brickwork in the ditches
that drain off the water from the neighbouring fields into the Mutlah
estuary. The latter sponge, however, perishes as these ditches dry up,
at an earlier period than that at which _S. alba_ reaches its maximum
development.