THE INTERNATIONAL SCIENTIFIC SERIES.
VOLUME XV.
THE INTERNATIONAL SCIENTIFIC SERIES.
_Works already Published._
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J. Tyndall, LL.D., F.R.S. With 26 Illustrations.
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the Principles of "Natural Selection" and "Inheritance" to
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XIV. THE CHEMISTRY OF LIGHT AND PHOTOGRAPHY; in its Application
to Art, Science, and Industry. By Dr. Hermann Vogel.
One Hundred Illustrations. (_In press._)
XV. FUNGI; their Nature, Influence, and Uses. By M. C. Cooke, M.A.,
LL.D. Edited by Rev. M. J. Berkeley, M.A., F.L.S. With
109 Illustrations. (_In press._)
XVI. OPTICS. By Professor Lommel, University of Erlangen.
(_In press._)
THE INTERNATIONAL SCIENTIFIC SERIES.
FUNGI:
THEIR
NATURE AND USES.
BY
M. C. COOKE, M.A., LL.D.
EDITED BY
THE REV. M. J. BERKELEY, M.A., F.L.S.
NEW YORK:
D. APPLETON AND COMPANY,
549 AND 551 BROADWAY.
1875.
PREFACE BY THE EDITOR.
As my name appears on the title-page of this volume, it is necessary
that I should exactly state what part I had in its preparation. I had
no doubt originally engaged to undertake the work myself; but finding,
from multiplicity of engagements and my uncertain health, that I could
not accomplish it satisfactorily, I thought the best course I could
take was to recommend Mr. Cooke to the publishers; a gentleman well
known, not only in this country, but in the United States. The whole
of the work has therefore been prepared by himself, the manuscript and
proof sheets being submitted to me from time to time, in which I
merely suggested such additions as seemed needful, subjoining
occasionally a few notes. As the work is intended for students, the
author has had no hesitation in repeating what has been stated in
former chapters where it has been thought to prove useful. I have no
doubt that the same high character will justly apply to this as to Mr.
Cooke's former publications, and especially to his "Handbook of
British Fungi."
M. J. BERKELEY.
SIBBERTOFT,
_November 23, 1874._
CONTENTS.
PAGE
I. NATURE OF FUNGI. 1
II. STRUCTURE. 17
III CLASSIFICATION 64
IV. USES. 82
V. NOTABLE PHENOMENA. 105
VI. THE SPORE AND ITS DISSEMINATION. 119
VII. GERMINATION AND GROWTH. 137
VIII. SEXUAL REPRODUCTION. 163
IX. POLYMORPHISM. 182
X. INFLUENCES AND EFFECTS. 209
XI. HABITATS. 233
XII. CULTIVATION. 253
XIII. GEOGRAPHICAL DISTRIBUTION. 266
XIV. COLLECTION AND PRESERVATION. 287
INDEX. 295
LIST OF ILLUSTRATIONS.
FIG. PAGE
1. Agaric in Process of Growth. 17
2. Section of Common Mushroom. 21
3. Sterile cells, Basidia, Cystidium, from _Gomphidius_. 21
4. _Polyporus giganteus_ (reduced). 23
5. _Hydnum repandum._ 24
6. _Calocera viscosa._ 24
7. _Tremella mesenterica._ 24
8. Basidia and spores of _Phallus_. 28
9. Basidia and spores of _Lycoperdon_. 29
10. Threads of _Trichia_. 31
11. _Arcyria incarnata_, with portion of threads and spore. 33
12. _Diachæa elegans._ 34
13. _Cyathus vernicosus._ 34
14. _Cyathus_, Sporangia and spores. 35
15. _Asterosporium Hoffmanni._ 36
16. Barren Cysts and Pseudospores of _Lecythea_. 36
17. _Coleosporium Tussilaginis._ 36
18. _Melampsora salicina_, pseudospores of 36
19. _Cystopus candidus_, conidia of 38
20. _Xenodochus carbonarius_, pseudospore. 38
21. _Phragmidium bulbosum_, pseudospores. 38
22. Pseudospores of _Puccinia_. 40
23. _Thecaphora hyalina_, pseudospores. 41
24. _Æcidium Berberidis_, peridia of 41
25. _Helminthosporium molle_, threads and spores. 42
26. _Acrothecium simplex._ 44
27. _Peronospora Arenariæ._ 44
28. _Polyactis cinerea._ 47
29. _Peziza Fuckeliana_, with ascus and sporidia. 47
30. _Penicillium chartarum._ 50
31. _Mucor mucedo_, with sporangia. 50
32. Small portion of _Botrytis Jonesii_. 54
33. Section of cup of _Ascobolus_. 57
34. Asci, sporidia, and paraphyses of _Ascobolus_. 59
35. Perithecium of _Sphæria_. 61
36. _Uncinula adunca_, conceptacle with appendages. 62
37. _Agaricus nudus._ 66
38. _Scleroderma vulgare_, Fr. 69
39. _Ceuthospora phacidioides._ 69
40. _Rhopalomyces candidus._ 74
41. _Mucor caninus._ 75
42. _Sphæria aquila_, cluster of perithecia. 78
43. _Morchella gigaspora_, from Kashmir. 99
44. _Cyttaria Gunnii_ 101
45. Spores of Agarics 121
46. Spores of _Lactarius_ 121
46a. Spores of _Gomphidius_ 122
47. Spores of _Polyporus_, _Boletus_, and _Hydnum_. 122
48. _Diachea elegans_, capellitium of 123
49. Spore of _Hendersonia polycystis_. 126
50. Spores of _Dilophospora graminis_. 126
51. Spores of _Discosia_. 126
52. Spore of _Prosthemium betulinum_. 126
53. Spore of _Stegonosporium cellulosum_. 126
54. Stylospores of _Coryneum disciforme_. 126
55. Spores of _Asterosporium Hoffmanni_. 126
56. Spores of _Pestalozzia_. 126
57. _Bispora monilioides_, concatenate spores 126
58. Pseudospores of _Thecaphora hyalina_. 128
59. Pseudospores of _Puccinia_. 128
60. Pseudospores of _Triphragmium_. 128
61. Pseudospores of _Phragmidium bulbosum_. 128
62. Winter spores of _Melampsora salicina._ 128
63. Spores of _Helicocoryne_. 129
64. Sporidium of _Genea verrucosa_. 130
65. Alveolate sporidium of _Tuber_. 130
66. Asci, sporidia, and paraphyses of _Ascobolus_. 131
67. Sporidium of _Ostreichnion Americanum_. 132
68. Ascus and sporidia of _Hypocrea_. 135
69. Sporidium of _Sphæria ulnaspora_. 135
70. Sporidia of _Valsa profusa_. 135
71. Sporidia of _Massaria foedans_. 135
72. Sporidium of _Melanconis bicornis_. 135
73. Caudate sporidia of _Sphæria fimiseda_. 135
74. Sporidia of _Valsa thelebola_. 135
75. Sporidia of _Valsa taleola_. 135
76. Sporidium of _Sporormia intermedia_. 135
77. Asci and sporidia of _Sphæria_ (_Pleospora_)
_herbarum_. 135
78. Sporidium of _Sphæria putaminum_. 135
79. Basidia and spores of _Exidia spiculosa_. 139
80. Germinating spore and corpuscles of _Dacrymyces_. 140
81. Germination of _Æcidium Euphorbia_. 142
82. Germinating pseudospores of _Coleosporium Sonchi_. 144
83. Germinating pseudospore of _Melampsora betulina_. 144
84. Germinating pseudospore of _Uromyce appendiculatus_. 145
85. Germinating pseudospore of _Puccinia Moliniæ_. 146
86. Germinating pseudospore of _Triphragmium Ulmariæ_. 146
87. Germinating pseudospore of _Phragmidium bulbosum_. 147
88. Germinating pseudospores of _Podisoma Juniperi_. 149
89. Germinating pseudospore of _Tilletia caries_. 150
90. Pseudospore of _Ustilago receptaculorum_ in germination,
and secondary spores in conjugation. 151
91. Conidia and zoospores of _Cystopus candidus_. 151
92. Resting spore of _Cystopus candidus_ with zoospores. 152
93. Zygospores of _Mucor phycomyces_. 158
94. Sporidium of _Ascobolus_ germinating. 161
95. Zygospore of _Mucor_. 164
96. Zygospore of _Rhizopus_ in different stages. 166
97. Conjugation in _Achlya racemosa_. 169
98. Conjugation in _Peronospora._ 171
99. Antheridia and oogonium of _Peronospora_. 172
100. Conjugation in _Peziza omphalodes_. 176
100a. Formation of conceptacle in _Erysiphe_. 176
101. _Tilletia caries_ with conjugating cells. 178
102. _Aspergillus glaucus_ and _Eurotium_. 190
103. _Erysiphe cichoracearum_, receptacle and mycelium. 192
104. Twig with _Tubercularia_ and _Nectria_. 193
105. Section of _Tubercularia_ with conidia. 193
106. D. _Nectria_ with _Tubercularia_, ascus and paraphyses. 195
107. Cells and pseudospores of _Æcidium berberidis_. 201
108. Cells and pseudospores of _Æcidium graveolens_. 201
109. _Torrubia militaris_ on pupa of a moth. 243
FUNGI
THEIR NATURE, USES, INFLUENCES, ETC.
I.
NATURE OF FUNGI.
The most casual observer of Nature recognizes in almost every instance
that comes under his notice in every-day life, without the aid of
logical definition, the broad distinctions between an animal, a plant,
and a stone. To him, the old definition that an animal is possessed of
life and locomotion, a plant of life without locomotion, and a mineral
deficient in both, seems to be sufficient, until some day he travels
beyond the circuit of diurnal routine, and encounters a sponge or a
zoophyte, which possesses only one of his supposed attributes of
animal life, but which he is assured is nevertheless a member of the
animal kingdom. Such an encounter usually perplexes the neophyte at
first, but rather than confess his generalizations to have been too
gross, he will tenaciously contend that the sponge must be a plant,
until the evidence produced is so strong that he is compelled to
desert his position, and seek refuge in the declaration that one
kingdom runs into the other so imperceptibly that no line of
demarcation can be drawn between them. Between these two extremes of
broad distinction, and no distinction, lies the ground occupied by the
scientific student, who, whilst admitting that logical definition
fails in assigning briefly and tersely the bounds of the three
kingdoms, contends that such limits exist so positively, that the
universal scientific mind accepts the recognized limit without
controversy or contradiction.
In like manner, if one kingdom be made the subject of inquiry, the
same difficulties will arise. A flowering plant, as represented by a
rose or a lily, will be recognized as distinct from a fern, a seaweed,
or a fungus. Yet there are some flowering plants which, at first
sight, and without examination, simulate cryptogams, as, for example,
many _Balanophoræ_, which the unscientific would at once class with
fungi. It is nevertheless true that even the incipient botanist will
accurately separate the phanerogams from the cryptogams, and by means
of a little more, but still elementary knowledge, distribute the
latter amongst ferns, mosses, fungi, lichens, and algæ, with
comparatively few exceptions. It is true that between fungi and
lichens there exists so close an affinity that difficulties arise, and
doubts, and disputations, regarding certain small groups or a few
species; but these are the exception, and not the rule. Botanists
generally are agreed in recognizing the five principal groups of
Cryptogamia, as natural and distinct. In proportion as we advance from
comparison of members of the three kingdoms, through that of the
primary groups in one kingdom, to a comparison of tribes, alliances,
and orders, we shall require closer observation, and more and more
education of the eye to see, and the mind to appreciate, relationships
and distinctions.
We have already assumed that fungi are duly and universally admitted,
as plants, into the vegetable kingdom. But of this fact some have even
ventured to doubt. This doubt, however, has been confined to one order
of fungi, except, perhaps, amongst the most illiterate, although now
the animal nature of the _Myxogastres_ has scarcely a serious advocate
left. In this order the early condition of the plant is pulpy and
gelatinous, and consists of a substance more allied to sarcode than
cellulose. De Bary insinuated affinities with _Amoeba_,[A] whilst
Tulasne affirmed that the outer coat in some of these productions
contained so much carbonate of lime that strong effervescence took
place on the application of sulphuric acid. Dr. Henry Carter is well
known as an old and experienced worker amongst amoeboid forms of
animal life, and, when in Bombay, he devoted himself to the
examination of the _Myxogastres_ in their early stage, and the result
of his examinations has been a firm conviction that there is no
relationship whatever between the _Myxogastres_ and the lower forms of
animal life. De Bary has himself very much modified, if not wholly
abandoned, the views once propounded by him on this subject. When
mature, and the dusty spores, mixed with threads, sometimes spiral,
are produced, the _Myxogastres_ are so evidently close allies of the
_Lycoperdons_, or Puffballs, as to leave no doubt of their affinities.
It is scarcely necessary to remark that the presence of zoospores is
no proof of animal nature, for not only do they occur in the white
rust (_Cystopus_), and in such moulds as _Peronospora_,[B] but are
common in algæ, the vegetable nature of which has never been
disputed.
There is another equally important, but more complicated subject to
which we must allude in this connection. This is the probability of
minute fungi being developed without the intervention of germs, from
certain solutions. The observations of M. Trécul, in a paper laid
before the French Academy, have thus been summarized:--1. Yeast cells
may be formed in the must of beer without spores being previously
sown. 2. Cells of the same form as those of yeast, but with different
contents, arise spontaneously in simple solution of sugar, or to which
a little tartrate of ammonia has been added, and these cells are
capable of producing fermentation in certain liquids under favourable
conditions. 3. The cells thus formed produce _Penicillium_ like the
cells of yeast. 4. On the other hand, the spores of _Penicillium_ are
capable of being transformed into yeast.[C] The interpretation of this
is, that the mould _Penicillium_ may be produced from a sugar
solution by "spontaneous generation," and without spore or germ of any
kind. The theory is, that a molecular mass which is developed in
certain solutions or infusions, may, under the influence of different
circumstances, produce either animalcules or fungi. "In all these
cases, no kind of animalcule or fungus is ever seen to originate from
preexisting cells or larger bodies, but always from molecules."[D] The
molecules are said to form small masses, which soon melt together to
constitute a globular body, from which a process juts out on one side.
These are the so-called _Torulæ_,[E] which give off buds which are
soon transformed into jointed tubes of various diameters, terminating
in rows of sporules, _Penicillium_, or capsules containing numerous
globular seeds, _Aspergillus_ (_sic_).
This is but another mode of stating the same thing as above referred
to by M. Trécul, that certain cells, resembling yeast cells (_Torula_),
are developed spontaneously, and that these ultimately pass through the
form of mould called _Penicillium_ to the more complex _Mucor_ (which
the writer evidently has confounded with _Aspergillus_, unless he
alludes to the ascigerous form of _Aspergillus_, long known as
_Eurotium_). From what is now known of the polymorphism of fungi, there
would be little difficulty in believing that cells resembling yeast
cells would develop into _Penicillium_, as they do in _fact_ in what is
called the "vinegar plant," and that the capsuliferous, or higher
condition of this mould may be a _Mucor_, in which the sporules are
produced in capsules. The difficulty arises earlier, in the supposed
spontaneous origination of yeast cells from molecules, which result from
the peculiar conditions of light, temperature, &c., in which certain
solutions are placed. It would be impossible to review all the
arguments, or tabulate all the experiments, which have been employed
for and against this theory. It could not be passed over in silence,
since it has been one of the stirring questions of the day. The great
problem how to exclude all germs from the solutions experimented
upon, and to keep them excluded, lies at the foundation of the theory.
It must ever, as we think, be matter of doubt that all germs were not
excluded or destroyed, rather than one of belief that forms known to be
developed day by day from germs should under other conditions
originate spontaneously.
Fungi are veritably and unmistakably plants, of a low organization, it
is true, but still plants, developed from germs, somewhat analogous,
but not wholly homologous, to the seeds of higher orders. The process
of fertilization is still obscure, but facts are slowly and gradually
accumulating, so that we may hope at some not very distant period to
comprehend what as yet are little removed from hypotheses. Admitting
that fungi are independent plants, much more complex in their
relations and development than was formerly supposed, it will be
expected that certain forms should be comparatively permanent, that
is, that they should constitute good species. Here, also, efforts have
been made to develop a theory that there are no legitimate species
amongst fungi, accepting the terms as hitherto applied to flowering
plants. In this, as in allied instances, too hasty generalizations
have been based on a few isolated facts, without due comprehension of
the true interpretation of such facts and phenomena. Polymorphism will
hereafter receive special illustration, but meantime it may be well to
state that, because some forms of fungi which have been described, and
which have borne distinct names as autonomous species, are now proved
to be only stages or conditions of other species, there is no reason
for concluding that no forms are autonomous, or that fungi which
appear and are developed in successive stages are not, in their
entirety, good species. Instead, therefore, of insinuating that there
are no good species, modern investigation tends rather to the
establishment of good species, and the elimination of those that are
spurious. It is chiefly amongst the microscopic species that
polymorphism has been determined. In the larger and fleshy fungi
nothing has been discovered which can shake our faith in the species
described half a century, or more, ago. In the Agarics, for instance,
the forms seem to be as permanent and as distinct as in the flowering
plants. In fact, there is still no reason to dissent, except to a very
limited extent, from what was written before polymorphism was
accredited, that, "with a few exceptions only, it may without doubt be
asserted that more certain species do not exist in any part of the
organized world than amongst fungi. The same species constantly recur
in the same places, and if kinds not hitherto detected present
themselves, they are either such as are well known in other districts,
or species which have been overlooked, and which are found on better
experience to be widely diffused. There is nothing like chance about
their characters or growth."[F]
The parasitism of numerous minute species on living and growing plants
has its parallel even amongst phanerogams in the mistletoe and
broom-rape and similar species. Amongst fungi a large number are thus
parasitic, distorting, and in many cases ultimately destroying, their
host, burrowing within the tissues, and causing rust and smut in corn
and grasses, or even more destructive and injurious in such moulds as
those of the potato disease and its allies. A still larger number of
fungi are developed from decayed or decaying vegetable matter. These
are found in winter on dead leaves, twigs, branches, rotten wood, the
remains of herbaceous plants, and soil largely charged with
disintegrated vegetables. As soon as a plant begins to decay it
becomes the source of a new vegetation, which hastens its destruction,
and a new cycle of life commences. In these instances, whether
parasitic on living plants or developed on dead ones, the source is
still vegetable. But this is not always the case, so that it cannot be
predicated that fungi are wholly epiphytal. Some species are always
found on animal matter, leather, horn, bone, &c., and some affect such
unpromising substances as minerals, from which it would be supposed
that no nourishment could be obtained, not only hard gravel stones,
fragments of rock, but also metals, such as iron and lead, of which
more may be said when we come to treat of the habitats of fungi.
Although in general terms fungi may be described as "hysterophytal or
epiphytal mycetals deriving nourishment by means of a mycelium from
the matrix,"[G] there are exceptions to this rule with which the
majority accord.
Of the fungi found on animal substances, none are more extraordinary
than those species which attack insects. The white mould which in
autumn proves so destructive to the common house-fly may for the
present be omitted, as it is probably a condition of one of the
_Saprolegniei_, which some authors include with fungi, and others with
algæ. Wasps, spiders, moths, and butterflies become enveloped in a
kind of mould named _Isaria_, which constitutes the conidia of
_Torrubia_, a genus of club-shaped _Sphæriæ_ afterwards developed.
Some species of _Isaria_ and _Torrubia_ also affect the larvæ and pupæ
of moths and butterflies, converting the whole interior into a mass of
mycelium, and fructifying in a clavate head. It has been subject for
discussion whether in such instances the fungus commenced its
development during the life of the insect, and thus hastened its
death, or whether it resulted after death, and was subsequent to the
commencement of decay.[H] The position in which certain large moths
are found standing on leaves when infested with _Isaria_ resembles so
closely that of the house-fly when succumbing to _Sporendonema Muscæ_,
would lead to the conclusion that certainly in some cases the insect
was attacked by the fungus whilst still living; whilst in the case of
buried caterpillars, such as the New Zealand or British _Hepialus_, it
is difficult to decide. Whether in life or death in these instances,
it is clear that the silk-worm disease _Muscardine_ attacks the living
insect, and causes death. In the case of the _Guêpes végétantes_, the
wasp is said to fly about with the fungus partially developed.
In all fungi we may recognize a vegetative and a reproductive system:
sometimes the first only becomes developed, and then the fungus is
imperfect, and sometimes the latter is far more prominent than the
former. There is usually an agglomeration of delicate threads,
either jointed or not, which are somewhat analogous to the roots of
higher plants. These delicate threads permeate the tissues of
plants attacked by parasitic fungi, or they run over dead leaves
forming whitened patches, formerly bearing the name of _Himantia_,
but really the mycelium of some species of _Marasmius_. If checked
or disturbed, the process stops here, and only a mycelium of
interwoven threads is produced. In this condition the mycelium of one
species so much resembles that of another, that no accurate
determination can be made. If the process goes on, this mycelium gives
rise to the stem and cap of an agaricoid fungus, completing the
vegetative system. This in turn gives origin to a spore-bearing
surface, and ultimately the fruit is formed, and then the fungus is
complete; no fungus can be regarded as perfect or complete without
its reproductive system being developed. In some this is very
simple, in others it is as complex. In many of the moulds we have
miniature representatives of higher plants in the mycelium or
roots, stem, branches, and at length capsules bearing sporidia, which
correspond to seeds. It is true that leaves are absent, but these are
sometimes compensated by lateral processes or abortive branchlets.
A tuft of mould is in miniature a forest of trees. Although such a
definition may be deemed more poetic than accurate, more figurative
than literal, yet few could believe in the marvellous beauty of a
tuft of mould if they never saw it as exhibited under the microscope.
In such a condition no doubt could be entertained of its vegetable
character. But there is a lower phase in which these plants are
sometimes encountered; they may consist only of single cells, or
strings of cells, or threads of simple structure floating in
fluids. In such conditions only the vegetative system is probably
developed, and that imperfectly, yet some have ventured to give
names to isolated cells, or strings of cells, or threads of
mycelium, which really in themselves possess none of the elements
of correct classification--the vegetative system, even, being
imperfect, and consequently the reproductive is absent. As already
observed, no fungus is perfect without fruit of some kind, and the
peculiarities of structure and development of fruit form one of the
most important elements in classification. To attempt, therefore, to
give names to such imperfect fragments of undeveloped plants is
almost as absurd as to name a flowering plant from a stray
fragment of a root-fibril accidentally cast out of the ground--nay,
even worse, for identification would probably be easier. It is well to
protest at all times against attempts to push science to the verge
of absurdity; and such must be the verdict upon endeavours to
determine positively such incomplete organisms as floating cells,
or hyaline threads which may belong to any one of fifty species of
moulds, or after all to an alga. This leads us to remark, in
passing, that there are forms and conditions under which fungi may
be found when, fructification being absent--that is, the vegetative
system alone developed--they approximate so closely to algæ that it
is almost impossible to say to which group the organisms belong.
Finally, it is a great characteristic of fungi in general that they
are very rapid in growth, and rapid in decay. In a night a puffball
will grow prodigiously, and in the same short period a mass of paste
may be covered with mould. In a few hours a gelatinous mass of
_Reticularia_ will pass into a bladder of dust, or a _Coprinus_ will
be dripping into decay. Remembering this, mycophagists will take note
that a fleshy fungus which may be good eating at noon may undergo such
changes in a few hours as to be anything but good eating at night.
Many instances have been recorded of the rapidity of growth in fungi;
it may also be accepted as an axiom that they are, in many instances,
equally as rapid in decay.
The affinity between lichens and fungi has long been recognized to its
full and legitimate extent by lichenologists and mycologists.[I] In
the "Introduction to Cryptogamic Botany," it was proposed to unite
them in one alliance, under the name of _Mycetales_, in the same
manner as the late Dr. Lindley had united allied orders under
alliances in his "Vegetable Kingdom;" but, beyond this, there was no
predisposition towards the theory since propounded, and which, like
all new theories, has collected a small but zealous circle of
adherents. It will be necessary briefly to summarize this theory and
the arguments by which it is supported and opposed, inasmuch as it is
intimately connected with our subject.
As recently as 1868, Professor Schwendener first propounded his
views,[J] and then briefly and vaguely, that all and every individual
lichen was but an algal, which had collected about it a parasitic
fungal growth, and that those peculiar bodies which, under the name of
_gonidia_, were considered as special organs of lichens, were only
imprisoned algæ. In language which the Rev. J. M. Crombie[K] describes
as "pictorial," this author gave the general conclusion at which he
had arrived, as follows:--"As the result of my researches, all these
growths are not simple plants, not individuals in the usual sense of
the term; they are rather colonies, which consist of hundreds and
thousands of individuals, of which, however, only one acts as master,
while the others, in perpetual captivity, provide nourishment for
themselves and their master. This master is a fungus of the order
_Ascomycetes_, a parasite which is accustomed to live upon the work of
others; its slaves are green algæ, which it has sought out, or indeed
caught hold of, and forced into its service. It surrounds them, as a
spider does its prey, with a fibrous net of narrow meshes, which is
gradually converted into an impenetrable covering. While, however, the
spider sucks its prey and leaves it lying dead, the fungus incites the
algæ taken in its net to more rapid activity; nay, to more vigorous
increase." This hypothesis, ushered upon the world with all the
prestige of the Professor's name, was not long in meeting with
adherents, and the cardinal points insisted upon were--1st. That the
generic relationship of the coloured "gonidia" to the colourless
filaments which compose the lichen thallus, had only been assumed, and
not proved; 2nd. That the membrane of the gonidia was chemically
different from the membrane of the other tissues, inasmuch as the
first had a reaction corresponding to that of algæ, whilst the second
had that of fungi; 3rd. That the different forms and varieties of
gonidia corresponded with parallel types of algæ; 4th. That as the
germination of the spore had not been followed further than the
development of a hypothallus, it might be accounted for by the absence
of the essential algal on which the new organism should become
parasitic; 5th. That there is a striking correspondence between the
development of the fruit in lichens and in some of the sporidiiferous
fungi (_Pyrenomycetes_).
These five points have been combated incessantly by lichenologists,
who would really be supposed by ordinary minds to be the most
practically acquainted with the structure and development of these
plants, in opposition to the theorists. It is a fact which should have
some weight, that no lichenologist of repute has as yet accepted the
theory. In 1873 Dr. E. Bornet[L] came to the aid of Schwendener, and
almost exhausted the subject, but failed to convince either the
practised lichenologist or mycologist. The two great points sought to
be established are these, that what we call lichens are compound
organisms, not simple, independent vegetable entities; and that this
compound organism consists of unicellular algæ, with a fungus
parasitic upon them. The coloured gonidia which are found in the
substance, or thallus of lichens, are the supposed algæ; and the
cellular structure which surrounds, encloses, and imprisons the
gonidia is the parasitic fungus, which is parasitic on something
infinitely smaller than itself, and which it entirely and absolutely
isolates from all external influences.
Dr. Bornet believed himself to have established that every gonidium of
a lichen may be referred to a species of algæ, and that the connection
between the hypha and gonidia is of such a nature as to exclude all
possibility of the one organ being produced by the other. This he
thinks is the only way in which it can be accounted for that the
gonidia of diverse lichens should be almost identical.
Dr. Nylander, in referring to this hypothesis of an imprisoned
algal,[M] writes: "The absurdity of such an hypothesis is evident from
the very consideration that it cannot be the case that an organ
(gonidia) should at the same time be a parasite on the body of which
it exercises vital functions; for with equal propriety it might be
contended that the liver or the spleen constitutes parasites of the
mammiferæ. Parasite existence is autonomous, living upon a foreign
body, of which nature prohibits it from being at the same time an
organ. This is an elementary axiom of general physiology. But
observation directly made teaches that the green matter originally
arises within the primary chlorophyll- or phycochrom-bearing cellule,
and consequently is not intruded from any external quarter, nor arises
in any way from any parasitism of any kind. The cellule at first is
observed to be empty, and then, by the aid of secretion, green matter
is gradually produced in the cavity and assumes a definite form. It
can, therefore, be very easily and evidently demonstrated that the
origin of green matter in lichens is entirely the same as in other
plants." On another occasion, and in another place, the same eminent
lichenologist remarks,[N] as to the supposed algoid nature of
gonidia--"that such an unnatural existence as they would thus pass,
enclosed in a prison and deprived of all autonomous liberty, is not
at all consonant with the manner of existence of the other algæ, and
that it has no parallel in nature, for nothing physiologically
analogous occurs anywhere else. Krempelhuber has argued that there are
no conclusive reasons against the assumption that the lichen-gonidia
may be self-developed organs of the lichen proper rather than algæ,
and that these gonidia can continue to vegetate separately, and so be
mistaken for unicellular algæ." In this Th. Fries seems substantially
to concur. But there is one strong argument, or rather a repetition of
an argument already cited, placed in a much stronger light, which is
employed by Nylander in the following words:--"So far are what are
called algæ, according to the turbid hypothesis of Schwendener, from
constituting true algæ, that on the contrary it may be affirmed that
they have a lichenose nature, whence it follows that these pseudo-algæ
are in a systematic arrangement to be referred rather to the lichens,
and that the class of algæ hitherto so vaguely limited should be
circumscribed by new and truer limits."
As to another phase in this question, there are, as Krempelhuber
remarks, species of lichens which in many countries do not fructify,
and whose propagation can only be carried on by means of the soredia,
and the hyphæ of such could in themselves alone no more serve for
propagation than the hyphæ from the pileus or stalk of an Agaric,
while it is highly improbable that they could acquire this faculty by
interposition of a foreign algal. On the other hand he argues: "It is
much more conformable to nature that the gonidia, as self-developed
organs of the lichens, should, like the spores, enable the hyphæ
proceeding from them to propagate the individual."[O]
A case in point has been adduced[P] in which gonidia were produced by
the hypha, and the genus _Emericella_,[Q] which is allied to _Husseia_
in the _Trichogastres_, shows a structure in the stem exactly
resembling _Palmella botryoides_ of Greville, and to what occurs in
_Synalyssa_. _Emericella_, with one or two other genera, must,
however, be considered as connecting _Trichogastres_ with lichens, and
the question cannot be considered as satisfactorily decided till a
series of experiments has been made on the germination of lichen
spores and their relation to free algæ considered identical with
gonidia. Mr. Thwaites was the first to point out[R] the relation of
the gonidia in the different sections of lichens to different types of
supposed algæ. The question cannot be settled by mere _à priori_
notions. It is, perhaps, worthy of remark that in _Chionyphe Carteri_
the threads grow over the cysts exactly as the hypha of lichens is
represented as growing over the gonidia.
Recently, Dr. Thwaites has communicated his views on one phase of this
controversy,[S] which will serve to illustrate the question as seen
from the mycological side. As is well known, this writer has had
considerable experience in the study of the anatomy and physiology of
all the lower cryptogamia, and any suggestion of his on such a subject
will at least commend itself to a patient consideration.
"According to our experience," he writes, "I think parasitic fungi
invariably produce a sad effect upon the tissues they fix themselves
upon or in. These tissues become pale in colour, and in every respect
sickly in appearance. But who has ever seen the gonidia of lichens the
worse for having the 'hypha' growing amongst them? These gonidia are
always in the plumpest state, and with the freshest, healthiest colour
possible. Cannot it enter into the heads of these most patient and
excellent observers, that a cryptogamic plant may have two kinds of
tissue growing side by side, without the necessity of one being
parasitic upon the other, just as one of the higher plants may have
half a dozen kinds of tissue making up its organization? The
beautifully symmetrical growth of the same lichens has seemed to me a
sufficient argument against one portion being parasitic upon another,
but when we see all harmony and robust health, the idea that one
portion is subsisting parasitically upon another appears to me to be a
perfect absurdity."
It appears to us that a great deal of confusion and a large number of
errors which creep into our modern generalizations and hypotheses, may
be traced to the acceptance of analogies for identities. How many
cases of mistaken identity has the improvement of microscopes revealed
during the past quarter of a century. This should at least serve as a
caution for the future.
Apart, however, from the "gonidia," whatever they may be, is the
remainder of the lichen a genuine fungus? Nylander writes, "The
anatomical filamentose elements of lichens are distinguished by
various characters from the hyphæ of fungi. They are firmer, elastic,
and at once present themselves in the texture of lichens. On the other
hand, the hyphæ of fungi are very soft, they possess a thin wall, and
are not at all gelatinous, while they are immediately dissolved by the
application of hydrate of potash, &c."[T]
Our own experience is somewhat to the effect, that there are some few
lichens which are doubtful as to whether they are fungi or lichens,
but, in by far the majority of cases, there is not the slightest
difficulty in determining, from the peculiar firmness and elasticity
of the tissues, minute peculiarities which the practised hand can
detect rather than describe, and even the general character of the
fruit that they differ materially from, though closely allied to
fungi. We have only experience to guide us in these matters, but that
is something, and we have no experience in fungi of anything like a
_Cladonia_, however much it may resemble a _Torrubia_ or _Clavaria_.
We have _Pezizæ_ with a subiculum in the section _Tapesia_, but the
veriest tyro would not confound them with species of _Parmelia_. It is
true that a great number of lichens, at first sight, and casually,
resemble species of the _Hysteriacei_, but it is no less strange than
true, that lichenologists and mycologists know their own sufficiently
not to commit depredations on each other.
Contributions are daily being made to this controversy, and already
the principal arguments on both sides have appeared in an English
dress,[U] hence it will be unnecessary to repeat those which are
modifications only of the views already stated, our own conclusions
being capable of a very brief summary: that lichens and fungi are
closely related the one to the other, but that they are not identical;
that the "gonidia" of lichens are part of the lichen-organization, and
consequently are not algæ, or any introduced bodies; that there is no
parasitism; and that the lichen thallus, exclusive of gonidia, is
wholly unknown amongst fungi.
The Rev. J. M. Crombie has therefore our sympathies in the remark with
which his summary of the gonidia controversy closes, in which he
characterizes it as a "sensational romance of lichenology," of the
"unnatural union between a captive algal damsel and a tyrant fungal
master."
[A] De Bary, "Des Myxomycètes," in "Ann. des Sci. Nat." 4 sér. xi. p.
153; "Bot. Zeit." xvi. p. 357. De Bary's views are controverted
by M. Wigand in "Ann. des Sci. Nat." 4 sér. (Bot.) xvi. p. 255,
&c.
[B] De Bary, "Recherches sur le Developpement de quelques Champignons
Parasites," in "Ann. des Sci. Nat." 4 sér. (Bot.) xx. p. 5.
[C] "Popular Science Review," vol. viii. p. 96.
[D] Dr. J. H. Bennett "On the Molecular Origin of Infusoria," p. 56.
[E] They have, however, no close relation with real _Torulæ_, such as
_T. monilioides_, &c.--COOKE'S _Handbook_, p. 477.
[F] Berkeley's "Outlines of British Fungology," p. 24.
[G] Berkeley's "Introduction to Cryptogamic Botany," p. 235.
[H] Gray, "Notices of Insects which form the Basis of Fungoid
Parasites."
[I] On the relation or connection between fungi and lichens, H. C.
Sorby has some pertinent remarks in his communication to the
Royal Society on "Comparative Vegetable Chromatology"
(Proceedings Royal Society, vol. xxi. 1873, p. 479), as one
result of his spectroscopic examinations. He says, "Such being
the relations between the organs of reproduction and the
foliage, it is to some extent possible to understand the
connection between parasitic plants like fungi, which do not
derive their support from the constructive energy of their
fronds, and those which are self-supporting and possess true
fronds. In the highest classes of plants the flowers are
connected with the leaves, more especially by means of
xanthophyll and yellow xanthophyll, whereas in the case of
lichens the apothecia contain very little, if any, of those
substances, but a large amount of the lichenoxanthines so
characteristic of the class. Looking upon fungi from this
chromatological point of view, they bear something like the
same relation to lichens that the petals of a leafless
parasitic plant would bear to the foliage of one of normal
character--that is to say, they are, as it were, the coloured
organs of reproduction of parasitic plants of a type closely
approaching that of lichens, which, of course, is in very
close, if not in absolute agreement with the conclusions drawn
by botanists from entirely different data."
[J] Schwendener, "Untersuchungen über den Flechtenthallus."
[K] Crombie (J. M.) "On the Lichen-Gonidia Question," in "Popular
Science Review" for July, 1874.
[L] Bornet, (E.), "Recherches sur les Gonidies des Lichens," in "Ann.
des Sci. Nat." 1873, 5 sér. vol. xvii.
[M] Nylander, "On the Algo-Lichen Hypothesis," &c., in "Grevillea,"
vol. ii. (1874), No. 22, p. 146.
[N] In Regensburg "Flora," 1870, p. 92.
[O] Rev. J. M. Crombie, in "Popular Science Review," July, 1874.
[P] Berkeley's "Introduction to Cryptogamic Botany," p. 373, fig.
78_a._
[Q] Berkeley's "Introduction," p. 341, fig. 76.
[R] "Annals and Magazine of Natural History," April, 1849.
[S] In "Gardener's Chronicle" for 1873, p. 1341.
[T] "Grevillea," vol ii. p. 147, in note.
[U] W. Archer, in "Quart. Journ. Micr. Sci." vol. xiii. p. 217; vol.
xiv. p. 115. Translation of Schwendener's "Nature of the
Gonidia of Lichens," in same journal, vol. xiii. p. 235.
II.
STRUCTURE.
Without some knowledge of the structure of fungi, it is scarcely
possible to comprehend the principles of classification, or to
appreciate the curious phenomena of polymorphism. Yet there is so
great a variety in the structure of the different groups, that this
subject cannot be compressed within a few paragraphs, neither do we
think that this would be desired if practicable, seeing that the
anatomy and physiology of plants is, in itself, sufficiently important
and interesting to warrant a rather extended and explicit survey. In
order to impart as much practical utility as possible to this chapter,
it seems advisable to treat some of the most important and typical
orders and suborders separately, giving prominence to the features
which are chiefly characteristic of those sections, following the
order of systematists as much as possible, whilst endeavouring to
render each section independent to a considerable extent, and complete
in itself. Some groups naturally present more noteworthy features than
others, and will consequently seem to receive more than their
proportional share of attention, but this seeming inequality could
scarcely have been avoided, inasmuch as hitherto some groups have been
more closely investigated than others, are more intimately associated
with other questions, or are more readily and satisfactorily examined
under different aspects of their life-history.
[Illustration: FIG. 1.--Agaric in Process of Growth.]