or suspension of organic functions, in the hybernation or winter sleep
both of warm and cold-blooded animals, in the dormice, marmots, sand
martins (Hirundo riparia) according to Cuvier (Règne animal, 1829, T.
i. p. 396), frogs and toads. Frogs, awakened from winter-sleep by
warmth, can support an eight times’ longer stay under water without
being drowned, than frogs in the breeding season. It would seem as if
the functions of the lungs in respiration, for some time after their
excitability had been suspended, required a less degree of activity.
The circumstance of the sand-martin sometimes burying itself in a
morass is a phenomenon which, while it seems not to admit of doubt, is
the more surprising, as in birds respiration is so extremely energetic,
that, according to Lavoisier’s experiments, two small sparrows, in
their ordinary state, decomposed, in the same space of time, as much
atmospheric air as a porpoise. (Lavoisier, Mémoires de Chimie, T. i. p,
119.) The winter-sleep of the swallow in question (the Hirundo riparia)
is not supposed to belong to the entire species, but only to have been
observed in some individuals. (Milne Edwards, Elémens de Zoologie,
1834, p. 543.)
As in the cold zone the deprivation of heat causes some animals to fall
into winter-sleep, so the hot tropical countries afford an analogous
phænomenon, which has not been sufficiently attended to, and to which
I have applied the name of summer-sleep. (Relation historique, T. ii.
pp. 192 and 626.) Drought and continuous high temperatures act like the
cold of winter in diminishing excitability. In Madagascar, (which, with
the exception of a very small portion at its southern extremity, is
entirely within the tropical zone,) as Bruguière had before observed,
the hedgehog-like Tenrecs (Centenes, Illiger), one species of which (C.
ecaudatus) has been introduced into the Isle of France, sleep during
great heat. Desjardins makes, it is true, the objection that the time
of their slumber is the winter season of the southern hemisphere; but
in a country in which the mean temperature of the coldest month is 3°
Reaumur (6°.75 Fah.) above that of the hottest month in Paris, this
circumstance cannot change the three months’ “summer-sleep” of the
Tenrec in Madagascar and at Port Louis, into what we understand by a
winter-sleep, or state of hybernation.
In the hot and dry season, the crocodile in the Llanos of Venezuela,
the land and water tortoises of the Orinoco, the huge boa, and several
smaller kinds of serpents, become torpid and motionless, and lie
incrusted in the indurated soil. The missionary Gili relates that the
natives, in seeking for the slumbering Terekai (land tortoises), which
they find lying at a depth of sixteen or seventeen inches in dried
mud, are sometimes bitten by serpents which become suddenly aroused,
and which had buried themselves at the same time as the tortoise. An
excellent observer, Dr. Peters, who has just returned from the East
Coast of Africa, writes thus to me on the subject:--“During my short
stay at Madagascar I could obtain no certain information respecting
the Tenrec; but, on the other hand, I know that in the East of
Africa, where I lived for several years, different kinds of tortoises
(Pentonyx and Trionchydias) pass months during the dry season of this
tropical country inclosed in the dry hard earth, and without food. The
Lepidosiren also, in places where the swamps are dried up, remains
coiled up and motionless, encased in indurated earth, from May to
December.”
Thus we find an annual enfeeblement of certain vital functions in
many and very different classes of animals, and, what is particularly
striking, without the same phenomena being presented by other living
creatures nearly allied to them, and belonging to the same family. The
northern glutton (Gulo), though allied to the badger (Meles), does
not like him sleep during the winter; whereas, according to Cuvier’s
remark, “a Myoxus (dormouse) of Senegal (Myoxus coupeii), which could
never have known winter-sleep in his tropical home, being brought
to Europe fell asleep the first year on the setting in of winter.”
This torpidity or enfeeblement of the vital functions and vital
activity passes through several gradations, according as it extends
to the processes of nutrition, respiration, and muscular motion, or
to depression of the activity of the brain and nervous system. The
winter-sleep of the solitary bears and of the badger is not accompanied
by any rigidity, and hence the reawakening of these animals is so
easy, and, as was often related to me in Siberia, so dangerous to the
hunters and country people. The first recognition of the gradation and
connection of these phenomena leads us up to what has been called the
“vita minima” of the microscopic organisms, which, occasionally with
green ovaries and undergoing the process of spontaneous division, fall
from the clouds in the Atlantic sand-rain. The apparent revivification
of rotiferæ, as well as of the siliceous-shelled infusoria, is only the
renewal of long-enfeebled vital functions,--a state of vitality which
was never entirely extinct, and which is fanned into a fresh flame, or
excited anew, by the appropriate stimulus. Physiological phenomena can
only be comprehended by being traced throughout the entire series of
analogous modifications.
[4] p. 5.--“_Winged insects._”
Formerly the fertilization of flowers in which the sexes are separated
was ascribed principally to the action of the wind: it has been
shown by Kölreuter, and with great ingenuity by Sprengel, that bees,
wasps, and a host of smaller winged insects, are the chief agents.
I say the chief agents, because to assert that no fertilization is
possible without the intervention of these little animals appears to
me not to be in conformity with nature, as indeed has been shown in
detail by Willdenow. (Grundriss der Kräuterkunde, 4te Aufl., Berl.
1805, S. 405-412.) On the other hand, Dichogamy, coloured spots or
marks indicating honey-vessels (maculæ indicantes), and fertilization
by insects, are, in much the greater number of cases, inseparably
associated. (Compare Auguste de St. Hilaire, Leçons de Botanique, 1840,
p. 565-571.)
The statement which has been often repeated since Spallanzani, that the
diœcious common hemp (Cannabis sativa) yields perfect seeds without
the neighbourhood of pollen-bearing vessels, has been refuted by later
experiments. When seeds have been obtained, anthers in a rudimentary
state, capable of furnishing some grains of fertilizing dust, have
been discovered near the ovarium. Such hermaphroditism is frequent
in the entire family of Urticeæ, but a peculiar and still unexplained
phenomenon has been presented in the forcing-houses at Kew by a small
New Holland shrub, the Cœlebogyne of Smith. This phænogamous plant
produces in England perfect seeds without trace of male organs, or the
hybridising introduction of the pollen of other species. An ingenious
botanist, Adrien de Jussieu, in his “Cours Elementaire de Botanique,”
1840, p. 463, expresses himself on the subject as follows:--“Un genre
d’Euphorbiacées (?) assez nouvellement décrit mais cultivé depuis
plusieurs années dans les serres d’Angleterre, le Cœlebogyne, y a
plusieurs fois fructifié, et ses graines étaient évidemment parfaites,
puisque non seulement on y a observé un embryon bien constitué, mais
qu’en le semant cet embryon s’est développé en une plante semblable.
Or les fleurs sont dioïques; on ne connait et ne possède pas (en
Angleterre) de pieds mâles, et les recherches les plus minutieuses,
faites par les meilleurs observateurs, n’ont pu jusqu’ici faire
découvrir la moindre trace d’anthères ou seulement de pollen. L’embryon
ne venait donc pas de ce pollen, qui manque entièrement: il a dû se
former de toute pièce dans l’ovule.”
In order to obtain a fresh confirmation or elucidation of this highly
important and isolated phenomenon, I addressed myself not long since
to my young friend Dr. Joseph Hooker, who, after making the Antarctic
voyage with Sir James Ross, has now joined the great Thibeto-Himalayan
expedition. Dr. Hooker wrote to me in reply, on his arrival at
Alexandria near the end of December 1847, before embarking at Suez:
“Our Cœlebogyne still flowers with my father at Kew as well as in the
Gardens of the Horticultural Society. It ripens its seeds regularly: I
have examined it repeatedly very closely and carefully, and have never
been able to discover a penetration of pollen-tubes either in the style
or ovarium. In my herbarium the male blossoms are in small catkins.”
[5] p. 7.--“_Shine like stars._”
The luminosity of the ocean is one of those superb natural phenomena
which continue to excite our admiration even when we have seen them
recur every night for months. The sea is phosphorescent in every zone;
but those who have not witnessed the phenomenon within the tropics, and
especially in the Pacific, have only an imperfect idea of the grand
and majestic spectacle which it affords. When a man-of-war, impelled
by a fresh breeze, cuts the foaming waves, the voyager standing at the
ship’s side feels as if he could never be satisfied with gazing on the
spectacle which presents itself to his view. Every time that in the
rolling of the vessel her side emerges from the water, blue or reddish
streams of light appear to dart upwards like flashes of lightning from
her keel. Nor can I describe the splendour of the appearance presented
on a dark night in the tropic seas by the sports of a troop of
porpoises. As they cut through the foaming waves, following each other
in long winding lines, one sees their mazy track marked by intense
and sparkling light. In the Gulf of Cariaco, between Cumana and the
Peninsula of Maniquarez, I have stood for hours enjoying this spectacle.
Le Gentil and the elder Forster attributed the flashing to the electric
friction excited by the ship in moving through the water, but the
present state of our knowledge does not permit us to receive this as a
valid explanation. (Joh. Reinh. Forster’s Bemerkungen auf seiner Reise
um die Welt, 1783, S. 57; Le Gentil, Voyage dans les Mers de l’Inde,
1779, T. i. p. 685-698.)
Perhaps there are few natural subjects of observation which have been
so long and so much debated as the luminosity of the waters of the
sea. What we know with certainty on the subject may be reduced to the
following simple facts. There are several luminous animals which,
when alive, give out at pleasure a faint phosphoric light: this light
is, in most instances, rather bluish, as in Nereis noctiluca, Medusa
pelagica var. β (Forskäl, Fauna Ægyptiaco-arabica, s. Descriptiones
animalium quæ in itinere orientali observavit, 1775, p. 109), and in
the Monophora noctiluca, discovered in Baudin’s expedition, (Bory de
St.-Vincent, Voyage dans les Iles des Mers d’Afrique, 1804, T. i. p.
107, pl. vi.) The luminous appearance of the sea is due partly to
living animals, such as are spoken of above, and partly to organic
fibres and membranes derived from the destruction of these living
torch-bearers. The first of these causes is undoubtedly the most
usual and most extensive. In proportion as travellers engaged in the
investigation of natural phenomena have become more zealous in their
researches, and more experienced in the use of excellent microscopes,
we have seen in our zoological systems the groups of Mollusca and
Infusoria, which become luminous either at pleasure or when excited by
external stimulus, increase more and more.
The luminosity of the sea, so far as it is produced by living organic
beings, is principally due, in the class of Zoophytes, to the Acalephæ
(the families of Medusa and Cyanea), to some Mollusca, and to a
countless host of Infusoria. Among the small Acalephæ, the Mammaria
scintillans offers the beautiful spectacle of, as it were, the starry
firmament reflected by the surface of the sea. This little creature,
when full grown, hardly equals in size the head of a pin. Michaelis, at
Kiel, was the first to show that there are luminous siliceous-shelled
infusoria: he observed the flashing light of the Peridinium (a ciliated
animalcule), of the cuirassed Monad the Prorocentrum micans, and of
a rotifera to which he gave the name of Synchata baltica. (Michaelis
über das Leuchten der Ostsee bei Kiel, 1830, S. 17.) The same Synchata
baltica was subsequently discovered by Focke in the Lagunes of Venice.
My distinguished friend and Siberian travelling companion, Ehrenberg,
has succeeded in keeping luminous infusoria from the Baltic alive
for almost two months in Berlin. He shewed them to me in 1832 with
a microscope in a drop of sea-water: placed in the dark I saw their
flashes of light. The largest of these little infusoria were 1-8th, and
the smallest from 1-48th to 1-96th of a Paris line in length (a Paris
line is about nine-hundredths of an English inch): after they were
exhausted, and had ceased to send forth sparkles of light, the flashing
was renewed on their being stimulated by the addition of acids or of a
little alcohol to the sea-water.
By repeatedly filtering water taken up fresh from the sea, Ehrenberg
succeeded in obtaining a fluid in which a greater number of these
luminous creatures were concentrated. (Abhandlungen der Akad. der
Wiss. zu Berlin aus dem J. 1833, S. 307; 1834, S. 537-575; 1838,
S. 45 and 258.) This acute observer has found in the organs of the
Photocaris, which emits flashes of light either at pleasure or when
irritated or stimulated, a cellular structure with large cells and
gelatinous interior resembling the electric organs of the Gymnotus and
the Torpedo. “When the Photocaris is irritated, one sees in each cirrus
a kindling and flickering of separate sparks, which gradually increase
in intensity until the whole cirrus is illuminated; until at last the
living fire runs also over the back of the small Nereis-like animal,
so that it appears in the microscope like a thread of sulphur burning
with a greenish-yellow light. It is a circumstance very deserving of
attention, that in the Oceania (Thaumantias) hemisphærica the number
and situation of the sparks correspond exactly with the thickened base
of the larger cirri or organs which alternate with them. The exhibition
of this wreath of fire is a vital act, and the whole development of
light is an organic vital process which in the Infusoria shows itself
as an instantaneous spark of light, and is repeated after short
intervals of repose.” (Ehrenberg über das Leuchten des Meeres, 1836, S.
110, 158, 160, and 163.)
According to these suppositions, the luminous creatures of the ocean
show the existence of a magneto-electric light-evolving process
in other classes of animals than fishes, insects, Mollusca, and
Acalephæ. Is the secretion of the luminous fluid which is effused in
some luminous creatures, and which continues to shine for some time
_without any farther influence of the living animal_ (for example, in
Lampyrides and Elaterides, in the German and Italian glow-worms, and
in the South American Cucuyo which lives on the sugar-cane), only a
consequence of the first electric discharge, or is it simply dependent
on chemical mixture? The shining of insects surrounded by air has
doubtless other physiological causes than those which occasion the
luminosity of inhabitants of the water, fishes, Medusæ, and Infusoria.
The small Infusoria of the ocean, being surrounded by strata of salt
water which is a good conducting fluid, must be capable of an enormous
electric tension of their light-flashing organs to enable them to shine
so intensely in the water. They strike like Torpedos, Gymnoti, and
the Tremola of the Nile, through the stratum of water; while electric
fishes, in connexion with the galvanic circuit, decompose water and
impart magnetism to steel bars, as I showed more than half a century
ago (Versuche über die gereizte Muskel- und Nervenfaser, Bd. i. S.
438-441, and see also Obs. de Zoologie et d’Anatomie comparée, vol.
i. p. 84); and as John Davy has since confirmed (Phil. Trans, for
1834, Part ii. p. 545-547), do not pass a flash through the smallest
intervening stratum.
The considerations which have been developed make it probable that
it is one and the same process which operates in the smallest living
organic creatures, so minute that they are not perceived by the naked
eye,--in the combats of the serpent-like gymnoti,--in flashing luminous
infusoria which raise the phosphorescence of the sea to such a degree
of brilliancy;--as well as in the thunder-cloud, and in the auroral,
terrestrial, or polar light (silent magnetic lightnings), which, as
the result of an increased tension in the interior of the globe, are
announced for hours beforehand by the suddenly altered movements of the
magnetic needle. (See my letter to the Editor of the Annalen der Physik
und Chemie, Bd. xxxvii. 1836, S. 242-244).
Sometimes one cannot even with high magnifying powers discern any
animalcules in the luminous water; and yet, whenever the wave strikes
and breaks in foam against a hard body, a light is seen to flash. In
such case the cause of the phenomenon probably consists in the decaying
animal fibres, which are disseminated in immense abundance throughout
the body of water. If this luminous water is filtered through fine and
closely woven cloths, these little fibres and membranes are separated
in the shape of shining points. When we bathed at Cumana in the waters
of the Gulf of Cariaco, and afterwards lingered awhile on the solitary
beach in the mild evening air without our clothes, parts of our bodies
continued luminous from the shining organic particles which had
adhered to the skin, and the light only became extinct at the end of
some minutes. Considering the enormous quantity of animal life in all
tropical seas, it is, perhaps, not surprising that the sea water should
be luminous, even where no visible organic particles can be detached
from it. From the almost infinite subdivision of the masses of dead
Dagysæ and Medusæ, the sea may perhaps be looked on as a gelatinous
fluid, which as such is luminous, distasteful to, and undrinkable by
man, and capable of affording nourishment to many fish. If one rubs
a board with part of a Medusa hysocella, the part so rubbed regains
its luminosity on friction with a dry finger. On my passage to South
America I sometimes placed a Medusa on a tin plate. When I struck
another metallic substance against the plate, the slightest vibrations
of the tin were sufficient to cause the light. What is the manner in
which in this case the blow and the vibrations act? Is the temperature
momentarily augmented? Are new surfaces exposed? or does the blow press
out a fluid, such as phosphuretted hydrogen, which may burn on coming
into contact with the oxygen of the atmosphere or of the air held in
solution by the sea-water. This light-exciting influence of a shock or
blow is particularly remarkable in a “cross sea,” _i. e._ when waves
coming from opposite directions meet and clash.
I have seen the sea within the tropics appear luminous in the most
different states of weather; but the light was most brilliant
when a storm was near, or with a sultry atmosphere and a vaporous
thickly-clouded sky. Heat and cold appear to have little influence on
the phenomenon, for on the Banks of Newfoundland the phosphorescence
is often very bright during the coldest winter weather. Sometimes
under apparently similar external circumstances the sea will be highly
luminous one night and not at all so the following night. Does the
atmosphere influence the disengagement of light, or do all these
differences depend on the accident of the observer sailing through a
part of the sea more or less abundantly impregnated with gelatinous
animal substances? Perhaps it is only in certain states of the
atmosphere that the light-evolving animalculæ come in large numbers to
the surface of the sea. It has been asked why the fresh water of our
marshes, which is filled with polypi, is never seen to become luminous.
Both in animals and plants, a particular mixture of organic particles
appears to be required in order to favour the production of light.
Willow-wood is oftener found to be luminous than oak-wood. In England
experiments have succeeded in making saltwater shine by pouring into
it the liquor from pickled herrings. It is easy to shew by galvanic
experiments that in living animals the evolution of light depends on
an irritation of the nerves. I have seen an Elater noctilucus which
was dying emit strong flashes of light when I touched the ganglion of
his fore leg with zinc and silver. Medusæ sometimes shew increased
brightness at the moment of completing the galvanic circuit. (Humboldt,
Relat. Hist. T. i. p. 79 and 533.)
Respecting the wonderful development of mass and power of increase in
Infusoria, see Ehrenberg, Infus. S. xiii. 291 and 512. He observes that
“the galaxy of the minutest organisms passes through the genera of
Vibrio and Bacterium and that of Monas, (in the latter they are often
only 1/3000 of a line,)” S. xix. and 244.
[6] p. 7.--“_Which inhabits the large pulmonary cells of the
rattle-snake of the tropics._”
This animal, which I formerly called an Echinorhynchus or even a
Porocephalus, appears on closer investigation, and according to the
better founded judgment of Rudolphi, to belong to the division of
the Pentastomes. (Rudolphi, Entozoorum Synopsis, p. 124 and 434.) It
inhabits the ventral cavities and wide-celled lungs of a species of
Crotalus which lives in Cumana, sometimes in the interior of houses,
where it pursues the mice. Ascaris lumbrici (Gözen’s Eingeweidewürmer,
Tab. iv. Fig. 10,) lives under the skin of the common earthworm, and
is the smallest of all the species of Ascaris. Leucophra nodulata,
Gleichen’s pearl-animalcule, has been observed by Otto Friedrich Müller
in the interior of the reddish Nais littoralis. (Müller, Zoologia
danica, Fasc. II. Tab. lxxx. a--e.) Probably these microscopic animals
are again inhabited by others. All are surrounded by air poor in oxygen
and variously mixed with hydrogen and carbonic acid. Whether any animal
can live in _pure nitrogen_ is very doubtful. It might formerly have
been believed to be the case with Fischer’s Cistidicola farionis,
because according to Fourcroy’s experiments the swimming bladders
of fish appeared to contain an air entirely deprived of oxygen.
Erman’s experience and my own shew, however, that fresh-water fishes
never contain pure nitrogen in their swimming bladders. (Humboldt et
Provençal, sur la respiration des Poissons, in the Recueil d’Observ. de
Zoologie, Vol. ii. p. 194-216.) In sea-fish as much as 0·80 of oxygen
has been found, and according to Biot the purity of the air would
appear to depend on the depth at which the fish live. (Mémoires de
Physique et de Chimie de la Societé d’Arcueil, T. i. 1807, p. 252-281.)
[7] p. 8.--“_The collected labours of united Lithophytes._”
Following Linnæus and Ellis, the calcareous zoophytes,--among which
Madrepores, Meandrinæ, Astreæ, and Pocilloporæ, especially, produce
wall-like coral-reefs,--are inhabited by living creatures which were
long believed to be allied to the Nereids belonging to Cuvier’s
Annelidæ. The anatomy of these gelatinous little creatures has been
elucidated by the ingenious and extensive researches of Cavolini,
Savigny, and Ehrenberg. We have learnt that in order to understand the
entire organization of what are called the rock-building coral animals,
the scaffolding which survives them, _i. e._, the layers of lime, which
in the form of thin delicate plates or lamellæ are elaborated by vital
functions, must not be regarded as something extraneous to the soft
membranes of the food-receiving animal.