TRANSCRIBER’S NOTE
Italic text is denoted by _underscores_.
Footnote anchors are denoted by [number], and the footnotes have
been placed at the end of the book.
Chapter headings have been made consistent, with the title on a
single line and the author on the following line.
The Index in this book covers all four volumes.
Some minor changes to the text are noted at the end of the book.
Volume I of this set of four volumes can be found in Project
Gutenberg at: https://www.gutenberg.org/ebooks/74571
Volume II can be found in Project Gutenberg at:
https://www.gutenberg.org/ebooks/77792
Volume III can be found in Project Gutenberg at:
https://www.gutenberg.org/ebooks/77827
[Illustration: Butterflies and Other Insects
1, Callimorpha; 2, Prionus Cervicornus; 3, 6, Licæna; 4. Oryctes
Hercules; 5, Lucanus Cervus; 7, Zeryntina; 8, Lithosia; 9, Arctia;
10, Cynthia; 11, Papilio Œnora; 12, Oryctes Nasicornis; 13,
Melolontha; 14, Papilio Machaon; 15, Goliathus; 16, Ditiscus; 17,
Leptura; 18, Geotrupes; 19, 20, Vanessa; 21, Urania]
THE STORY OF
THE UNIVERSE
_Told by Great Scientists
and Popular Authors_
COLLECTED AND EDITED
_By_ ESTHER SINGLETON
Author of “Turrets, Towers and Temples,” “Wonders of Nature,”
“The World’s Great Events,” “Famous Paintings,” Translator
of Lavignac’s “Music Dramas of Richard Wagner”
_FULLY ILLUSTRATED_
VOLUME IV
THE
EARTH’S
CREATURES:
FAUNA
THE CURRENT LITERATURE
PUBLISHING CO.,
NEW YORK
COPYRIGHT 1905
P. F. COLLIER & SON
ILLUSTRATIONS
Butterflies and other Insects _Frontispiece_
Radiolaria _Opposite p._ 1327
Curious Zoophytes ” 1375
Fishes ” 1423
Shells ” 1495
Types of Extinct Fishes, Shells, and Crustacea ” 1543
Birds ” 1591
Fairy Flies ” 1639
American Reptiles ” 1687
CONTENTS
OMNIPRESENCE OF LIFE. George Henry Lewes 1285
THE ANIMAL KINGDOM. Thomas H. Huxley 1296
THE FOUR CLASSES. Baron Cuvier 1301
DEEP SEA FAUNA. Lord Kelvin 1304
“THE MIMIC FIRES OF OCEAN.” G. Clarke Nuttall 1320
THE JELLY-FISH AND OTHER HYDROZOA. P. Martin Duncan 1324
FISHES. Andrew Wilson 1337
WONDERS OF THE SHORE. Charles Kingsley 1357
CRABS, PRAWNS, AND LOBSTERS. Philip Henry Gosse 1374
REPTILES. Peter Mark Roget 1379
THE CLASSIFICATION AND ORIGIN OF INSECTS. Lord Avebury 1401
INSECTS: THEIR WINGS, STINGS, EARS, AND EYES.
Philip Henry Gosse 1425
FAIRY FLIES. Fred. Enock 1449
INSECT TRANSFORMATIONS. Andrew Wilson 1458
STRUGGLE FOR EXISTENCE. Charles Darwin 1464
NATURAL SELECTION. Charles Darwin. 1482
MAMMALIA. Baron Cuvier 1513
ZOOLOGICAL ZONES. Sir Richard Owen 1520
GEOGRAPHICAL DISTRIBUTION OF ANIMALS. William Hughes 1535
CETACEA. Peter Mark Roget 1561
HUNTING AND FISHING OF ANIMALS. Frédéric Houssay 1565
THE DEATH-FEIGNING INSTINCT. W. H. Hudson 1577
BIRDS. J. Arthur Thomson 1582
MIMICRY. David Robertson 1593
DWELLINGS. Frederic Houssay 1601
MAN’S FIRST APPEARANCE. Boyd Dawkins 1647
MAN’S PRIMITIVE CONDITION. Duke of Argyl 1656
RACES OF MANKIND. Wiliam Hughes 1667
THE HUMAN RACE. Louis Figuier 1679
INDEX 1695
THE STORY OF THE UNIVERSE
(VOLUME FOUR)
THE STORY OF THE UNIVERSE
OMNIPRESENCE OF LIFE
--GEORGE HENRY LEWES
Come with me, and lovingly study Nature, as she breathes, palpitates,
and works under myriad forms of Life-forms unseen, unsuspected, or
unheeded by the mass of ordinary men. Our course may be through park
and meadow, garden and lane, over the swelling hills and spacious
heaths, beside the running and sequestered streams along the tawny
coast, out on the dark and dangerous reefs, or under dripping caves
and slippery edges. It matters little where we go: everywhere--in
the air above, the earth beneath, and waters under the earth--we
are surrounded with Life. Avert your eyes a while from our human
world, with its ceaseless anxieties, its noble sorrow, poignant, yet
sublime, of conscious imperfection aspiring to higher states, and
contemplate the calmer activities of that other world with which we
are so mysteriously related. I hear you exclaim,
“The proper study of mankind is man;”
nor will I pretend, as some enthusiastic students seem to think, that
“The proper study of mankind is _cells_;”
but agreeing with you, that man is the noblest study, I would
suggest that under the noblest there are other problems which we must
not neglect. Man himself is imperfectly known, because the laws of
universal Life are imperfectly known. His life forms but one grand
illustration of Biology--the science of Life--as he forms but the
apex of the animal world.
Our studies here will be of Life, and chiefly of those minuter or
obscurer forms which seldom attract attention. In the air we breathe,
in the water we drink, in the earth we tread on, Life is everywhere.
Nature _lives_: every pore is bursting with Life; every death is only
a new birth, every grave a cradle. And of this we know so little,
think so little! Around us, above us, beneath us, that great mystic
drama of creation is being enacted, and we will not even consent
to be spectators! Unless animals are obviously useful or obviously
hurtful to us, we disregard them. Yet they are not alien, but akin.
The Life that stirs within us stirs within them. We are all “parts of
one transcendent whole.” The scales fall from our eyes when we think
of this; it is as if a new sense had been vouchsafed to us, and we
learn to look at Nature with a more intimate and personal love.
Life everywhere! The air is crowded with birds--beautiful, tender,
intelligent birds--to whom life is a song and a thrilling anxiety,
the anxiety of love. The air is swarming with insects--those little
animated miracles. The waters are peopled with innumerable forms,
from the animalcule, so small that one hundred and fifty millions
of them would not weigh a grain, to the whale, so large that it
seems an island as it sleeps upon the waves. The bed of the seas
is alive with polypes, crabs, star-fishes, and with sand-numerous
shell-animalcules. The rugged face of rocks is scarred by the silent
boring of soft creatures, and blackened with countless mussels,
barnacles, and limpets.
Life everywhere! on the earth, in the earth, crawling, creeping,
burrowing, boring, leaping, running. If the sequestered coolness of
the wood tempt us to saunter into its checkered shade, we are saluted
by the murmurous din of insects, the twitter of birds, the scrambling
of squirrels, the startled rush of unseen beasts, all telling how
populous is this seeming solitude. If we pause before a tree, or
shrub, or plant, our cursory and half-abstracted glance detects a
colony of various inhabitants. We pluck a flower, and in its bosom
we see many a charming insect busy at its appointed labor. We pick
up a fallen leaf, and if nothing is visible on it, there is probably
the trace of an insect larva hidden in its tissue, and awaiting there
development. The drop of dew upon this leaf will probably contain its
animals, visible under the microscope. This same microscope reveals
that the _blood-rain_ suddenly appearing on bread, and awakening
superstitious terrors, is nothing but a collection of minute animals
(Monas prodigiosa); and that the vast tracts of snow which are
reddened in a single night owe their color to the marvelous rapidity
in reproduction of a minute plant (Protococcus nivalis). The very
mould which covers our cheese, our bread, our jam, or our ink, and
disfigures our damp walls, is nothing but a collection of plants. The
many-colored fire which sparkles on the surface of a summer sea at
night, as the vessel plows her way, or which drips from the oars in
lines of jeweled light, is produced by millions of minute animals.
Nor does the vast procession end here. Our very mother-earth is
formed of the débris of life. Plants and animals which have been
built up its solid fabric. We dig downward thousands of feet below
the surface, and discover with surprise the skeletons of strange,
uncouth animals, which roamed the fens and struggled through the
woods before man was. Our surprise is heightened when we learn
that the very quarry itself is mainly composed of the skeletons of
microscopic animals; the flints which grate beneath our carriage
wheels are but the remains of countless skeletons. The Apennines and
Cordilleras, the chalk cliffs so dear to homeward-nearing eyes--these
are the pyramids of bygone generations of atomies. Ages ago these
tiny architects secreted the tiny shells which were their palaces;
from the ruins of these palaces we build our Parthenons, our St.
Peters, and our Louvres. So revolves the luminous orb of Life!
Generations follow generations; and the Present becomes the matrix
of the Future, as the Past was of the Present--the Life of one epoch
forming the prelude to a higher Life.
When we have thus ranged air, earth, and water, finding everywhere a
prodigality of living forms, visible and invisible, it might seem
as if the survey were complete. And yet it is not so. Life cradles
within Life. The bodies of animals are little worlds, having their
own animals and plants. A celebrated Frenchman has published a thick
octavo volume devoted to the classification and description of _The
Plants which Grow on Men and Animals_;[1] and many Germans have
described the immense variety of animals which grow on and in men and
animals; so that science can boast of a parasitic Flora and Fauna. In
the fluids and tissues, in the eye, in the liver, in the stomach, in
the brain, in the muscles, parasites are found, and these parasites
have often _their_ living parasites in them!
We have thus taken a bird’s-eye view of the field in which we may
labor. It is truly inexhaustible. We may begin where we please, we
shall never come to an end; our curiosity will never slacken.
“And whosoe’er in youth
Has through ambition of his soul given way
To such desires, and grasp’d at such delights,
Shall feel congenial stirrings late and long.”
As a beginning, get a microscope. If you can not borrow, boldly buy
one. Few purchases will yield you so much pleasure; and, while you
are about it, do, if possible, get a good one. Spend as little money
as you can on accessory apparatus and expensive fittings, but get a
good stand and good glasses. Having got your instrument, bear in mind
these two important trifles--work by daylight, seldom or never by
lamplight; and keep the unoccupied eye _open_. With these precautions
you may work daily for hours without serious fatigue to the eye.
Now where shall we begin? Anywhere will do. This dead frog, for
example, that has already been made the subject of experiments, and
is now awaiting the removal of its spinal cord, will serve us as
a text from which profitable lessons may be drawn. We snip out a
portion of its digestive tube, which, from its emptiness, seems to
promise little; but a drop of the liquid we find in it is placed on
a glass slide, covered with a small piece of very thin glass, and
brought under the microscope. Now look. There are several things
which might occupy your attention, but disregard them now to watch
that animalcule which you observe swimming about. What is it? It is
one of the largest of the Infusoria, and is named Opalina. When I
call this an Infusorium I am using the language of text-books; but
there seems to be a growing belief among zoologists that the Opalina
is not an Infusorium, but the infantile condition of some worm
(Distoma?). However, it will not grow into a mature worm as long as
it inhabits the frog; it waits till some pike or bird has devoured
the frog, and then, in the stomach of its new captor, it will develop
into its mature form--then, and not till then. This surprises you.
And well it may; but thereby hangs a tale, which to unfold--for the
present, however, it must be postponed, because the Opalina itself
needs all our notice.
Observe how transparent it is, and with what easy, undulating
grace it swims about; yet this swimmer has no arms, no legs, no
tail, no backbone to serve as a fulcrum to moving muscles--nay, it
has no muscles to move with. ’Tis a creature of the most absolute
abnegations--sans eyes, sans teeth, sans everything; no, not sans
everything, for, as we look attentively, we see certain currents
produced in the liquid, and, on applying a higher magnifying power,
we detect how these currents are produced. All over the surface of
the Opalina there are delicate hairs in incessant vibration; these
are the _cilia_.[2] They lash the water, and the animal is propelled
by their strokes, as a galley by its hundred oars. This is your first
sight of that ciliary action of which you have so often read, and
which you will henceforth find performing some important service
in almost every animal you examine. Sometimes the cilia act as
instruments of locomotion; sometimes as instruments of respiration,
by continually renewing the current of water; sometimes as the means
of drawing in food, for which purpose they surround the mouth, and by
their incessant action produce a small whirlpool into which the food
is sucked. An example of this is seen in the Vorticella.
Having studied the action of these cilia in microscopic animals, you
will be prepared to understand their office in your own organism.
It is an interesting fact, that while the direction in which the
cilia propel fluids and particles is generally toward the interior
of the organism, it is sometimes _reversed_, and, instead of beating
the particles inward, the cilia energetically beat them back if they
attempt to enter. Fatal results would ensue if this were not so.
Our air-passages would no longer protect the lungs from particles
of sand, coal-dust, and filings flying about the atmosphere; on the
contrary, the lashing hairs which cover the surface of these passages
would catch up every particle and drive it onward into the lungs.
Fortunately for us, the direction of the cilia is reversed, and they
act as vigilant janitors, driving back all vagrant particles with a
stern “No admittance, _even_ on business!” In vain does the whirlwind
dash a column of dust in our faces--in vain does the air, darkened
with coal-dust, impetuously rush up the nostrils; the air is allowed
to pass on, but the dust is inexorably driven back.
The swimming apparatus of the Opalina has led us far away from the
little animal who has been feeding while we have been lecturing.
At the mention of feeding you naturally look for the food that is
eaten, the mouth and stomach that eat. But I hinted just now that
this ethereal creature dispenses with a stomach, as too gross for its
nature, and, of course, by a similar refinement, dispenses with a
mouth. Indeed, it has no organs whatever except the cilia just spoken
of.
And this leads us to consider what biologists mean by an _organ_: it
is a particular portion of the body set apart for the performance
of some particular function. The whole process of development is
this setting apart for special purposes. The starting-point of Life
is a single cell--that is to say, a microscopic sac, filled with
liquid and granules, and having within it a nucleus, or smaller sac.
Paley has somewhere remarked that in the early stages there is no
difference discernible between a frog and a philosopher. It is very
true--truer than he conceived. In the earliest stage of all, both
the Batrachian and the Philosopher are nothing but single cells,
although the one cell will develop into an Aristotle or a Newton, and
the other will get no higher than the cold, damp, croaking animal
which boys will pelt, anatomists dissect, and Frenchmen eat. From
the starting-point of a single cell this is the course taken: the
cell divides itself into two, the two become four, the four eight,
and so on, till a mass of cells is formed not unlike the shape of
a mulberry. This mulberry-mass then becomes a sac, with double
envelopes or walls; the inner wall, turned toward the yelk, or food,
becomes the _assimilating_ surface for the whole; the outer wall,
turned toward the surrounding medium, becomes the surface which
is to bring frog and philosopher into contact and relation with
the external world--the Non-Ego, as the philosopher in after life
will call it. Here we perceive the first grand “setting apart,” or
_differentiation_, has taken place; the embryo having an assimilating
surface, which has little to do with the external world, and a
sensitive, contractile surface, which has little to do with the
preparation and transport of food. The embryo is no longer a mass
of similar cells; it is already become dissimilar, _different_, as
respects its inner and outer envelope. But these envelopes are at
present uniform; one part of each is exactly like the rest. Let us,
therefore, follow the history of Development, and we shall find that
the inner wall gradually becomes unlike itself in various parts,
and that certain organs, constituting a very complex apparatus of
Digestion, Secretion, and Excretion, are all one by one wrought out
of it by a series of metamorphoses or _differentiations_. The inner
wall thus passes from a simple assimilating surface to a complex
apparatus serving the functions of vegetative life.
Now glance at the outer wall: from it also various organs have
gradually been wrought; it has developed into muscles, nerves, bones,
organs of sense, and brain--all these from a simple homogeneous
membrane!
With this bird’s-eye view of the course of development you will be
able to appreciate the grand law first clearly enunciated by Goethe
and Von Baer as the law of animal life, namely, that development
is always from the general to the special, from the simple to the
complex, from the homogeneous to the heterogeneous, and this by a
gradual series of _differentiations_.
Here is our Opalina, for example, without mouth, or stomach, or
any other organ. It is an assimilating surface in every part; in
every part a breathing, sensitive surface. Living on liquid food,
it does not need a mouth to seize or a stomach to digest such food.
The liquid, or gas, passes through the Opalina’s delicate skin by a
process which is called _endosmosis_; it there serves as food; and
the refuse passes out again by a similar process, called _exosmosis_.
This is the way in which many animals and all plants are nourished.
The cell at the end of a rootlet, which the plant sends burrowing
through the earth, has no mouth to seize, no open pores to admit the
liquid that it needs; nevertheless, the liquid passes into the cell
through its delicate cell-wall, and passes from this cell to _other_
cells upward from the rootlet to the bud. It is in this way, also,
that the Opalina feeds: it is all-mouth, no-mouth; all-stomach,
no-stomach. Every part of its body performs the functions which in
more complex animals are performed by organs specially set apart.
It feeds without mouth, breathes without lungs, and moves without
muscles. The Opalina, as I have said, is a parasite. It may be found
in various animals, and almost always in the frog.
Nature is economic as well as prodigal of space. She fills the
illimitable heavens with planetary and starry grandeurs, and the
tiny atoms moving over the crust of earth she makes the homes of
the infinitely little. Far as the mightiest telescope can reach, it
detects worlds in clusters, like pebbles on the shore of infinitude;
deep as the microscope can penetrate, it detects life within life,
generation within generation, as if the very universe itself were not
vast enough for the energies of life!
THE ANIMAL KINGDOM
--THOMAS H. HUXLEY
As soon as the labors of anatomists had extended over a sufficiently
great variety of animals, it was found that they could be grouped
into separate assemblages, the members of each of which, while
varying more or less in minor respects, had certain structural
features in common, and these common morphological characters became
the definition of the group thus formed. The smallest group thus
constituted is a _Morphological Species_. A certain number of species
having characters in common, by which they resemble one another
and differ from all other species, constitutes a _Genus_; a group
of genera, similarly associated, constitutes a _Family_; a group
of families, an _Order_; a group of orders, a _Class_; a group of
classes, a _Sub-kingdom_; while the latter, agreeing with one another
only in the characters in which all animals agree, and in which they
differ from all plants, make up the _Animal Kingdom_.
Linnæus, living at a time when neither comparative anatomy nor
embryology can be said to have existed, based his classification
of animals upon such broad resemblances of adult structure and
habit as his remarkable sagacity and wide knowledge enabled him to
detect. Cuvier and his school devoted themselves to the working out
of adult structure, and the _Leçons d’Anatomie Comparée_ and the
_Règne Animal_ are wonderful embodiments of the results of such
investigations. But the Cuvierian system ignores development; and
it was reserved for Von Baer to show the importance of developmental
studies, and to inaugurate the marvelous series of researches which,
in the course of the last fifty years, have made us acquainted with
the manner of development of every important group of animals. The
splendid researches of Cuvier gave birth to scientific palæontology,
and demonstrated that, in some cases, at any rate, extinct forms of
life present characters intermediate between those of groups which
are at present widely different. The investigations of Agassiz upon
fossil fishes tended in the same direction, and further showed that,
in some cases, the older forms preserve, as permanent features,
structural characters which are embryonic and transitory in their
living congeners. Moreover, Darwin, Owen, and Wallace proved that,
in any great area of geographical distribution, the later tertiary
extinct forms are clearly related to those which now exist in
the area. As Taxonomic investigations increased in accuracy and
in extent, the careful examination of large suites of specimens
revealed an unexpected amount of variability in species; and
Darwin’s investigation of the phenomena presented by animals under
domestication proved that forms, morphologically as distinct as
admitted natural genera, could be produced by selective breeding from
a common stock.
The only genus of animals of which we possess a satisfactory, though
still not quite complete, ancestral history, is the genus Equus,
the development of which in the course of the Tertiary epoch from
an Anchitherioid ancestor, through the form of Hipparion, appears
to admit of no doubt. And all the facts of geology and palæontology
not only tend to show that the knowledge of ancestral development
is likely long to remain fragmentary, but lead us to doubt whether
even such fragments as may be vouchsafed to us by the extension of
geological inquiry will ever be sufficiently old, in relation to the
whole duration of life on the earth, to give us positive evidence of
the nature of the earliest forms of animals.
In the case of an existing animal, it is possible to determine its
adult structure and its development, and therefore to assign its
place relatively to other animals, the structure and development of
which are also known; and, in the case of an extinct animal, it is
possible to ascertain certain facts of its structure, and sometimes
certain facts of its development, which will justify a more or less
positive assignment of its place relatively to existing animals.
So far, Taxonomy is objective, capable of proof and disproof, and
it should leave speculation aside, until speculation has converted
itself into demonstration.
In the present rapidly shifting condition of our knowledge of the
facts of animal structure and development, however, it is no easy
matter to group these facts into general propositions which shall
express neither more nor less than is contained in the facts; and
no one can be more conscious of the manifold imperfections of the
following attempt at such a classification than the author of it.
In certain of the lower animals, the substance of the body is not
differentiated into histogenetic elements; that is, into cells[3]
which, by their metamorphoses, give rise to tissues. In all other
animals, on the other hand, the protoplasmic mass, which constitutes
the primitive body, is converted into a multitude of cells, which
become metamorphosed into the tissues of the body.
For the first of these divisions the old name of Protozoa may be
retained; for the second, the title of Metazoa, recently proposed by
Haeckel, may be conveniently employed.
The subjoined synopsis indicates the general relations of the
different groups of the animal kingdom.
Those who are familiar with the existing condition of our knowledge
of animal morphology will be aware that any such scheme must needs,
at present, be tentative and subject to extensive revision, in
correspondence with the advance of knowledge. Nor will they regard
it as any objection to the scheme of classification proposed, that
the divisions sketched out may be incapable of sharp definition--the
constant tendency of modern investigations being to break through
all boundaries of groups, and to fill up the gaps between them by
the discovery of transitional forms. In the place of assemblages of
distinctly definable groups, which it has hitherto been the object
of the taxonomist to define and co-ordinate in precise logical
categories, we are gradually learning to substitute series, in which
all the modifications by which a fundamental form passes from lower
to higher degrees of organic complication are summed up.
ANIMALIA
I.--PROTOZOA
i. MONERA
Protamœbidæ. Protomonadidæ. Myxastridæ, etc.
ii. ENDOPLASTICA
Amœbidæ. Flagellata. Gregarinidæ. Acinetida. Ciliata. Radiolaria
II.--METAZOA
A. Gastrææ
i. POLYSTOMATA
Porifera (or Spongida)
ii. MONOSTOMATA
1. ARCHÆOSTOMATA
α. _Scolecimorpha_ β. _Cœlenterata_
|
/-----------------|----------------\
Rotifera Nematoidea Hirudinea Hydrozoa
Turbellaria Oligochæta Actinozoa
Trematoda
2. DEUTEROSTOMATA
_a._ Schizocœla
|
/-------------------------|-------------------------\
_Annelida (Polychæta)_ _Gephyrea_ _Brachiopoda (?)_
_Arthropoda_ _Mollusca_ _Polyzoa (?)_
_b._ Enterocœla
|
/------------------------|------------------------\
_Enteropneusta_ _Chætognatha_ _Echinodermata_
_c._ Epicœla
|
/------------|----------\
_Tunicata_ _Vertebrata_
B. Agastrææ (provisional)
Acanthocephala. Cestoidea
THE FOUR CLASSES
--BARON CUVIER
If we consider only the organization and nature of animals, without
regard to their size, utility, the greater or less knowledge we
have of them, and other accessory circumstances, we shall find
there are four principal forms, four general plans, if it may be so
expressed, on which all animals seem to have been modeled, and whose
ulterior divisions, whatever be the titles with which naturalists
have decorated them, are merely slight modifications, founded on the
development or addition of certain parts, which produce no essential
change in the plan itself.
In the first of these forms, which is that of man and of the animals
most nearly resembling him, the brain and principal trunk of the
nervous system are inclosed in a bony envelope, formed by the cranium
and vertebræ; to the sides of this intermedial column are attached
the ribs and bones of the limbs, which form the framework of the
body; the muscles generally cover the bones, whose motions they
occasion, while the viscera are contained within the head and trunk.
Animals of this form we shall denominate Animalia Vertebrata. They
have, all, red blood, a muscular heart, a mouth furnished with two
jaws situated either above or before each other, distinct organs
of sight, hearing, smell, and taste placed in the cavities of the
face, never more than four limbs, the sexes always separated, and a
very similar distribution of the medullary masses and the principal
branches of the nervous system.
By a closer examination of each of the parts of this great series of
animals, we always discover some analogy, even in species the most
remote from each other; and may trace the gradations of one same plan
from man to the last of the fishes.
In the second form there is no skeleton; the muscles are merely
attached to the skin, which constitutes a soft contractile envelope,
in which, in many species, are formed stony plates, called shells,
whose position and production are analogous to those of the mucous
body. The nervous system is contained within this general envelope
along with the viscera, and is composed of several scattered masses
connected by nervous filaments; the chief of these masses is placed
on the æsophagus and is called the brain. Of the four senses, the
organs of two only are observable, those of taste and sight, the
latter of which are even frequently wanting. One single family alone
presents organs of hearing. There is always, however, a complete
system of circulation, and particular organs for respiration.
Those of digestion and secretion are nearly as complex as in the
vertebrata. We will distinguish the animals of this second form by
the appellation of Animalia Mollusca.
Although, as respects the external configuration of the parts, the
general plan of their organization is not as uniform as that of the
vertebrata, there is always an equal degree of resemblance between
them in the structure and the functions.
The third form is that remarked in worms, insects, etc. Their nervous
system consists of two long cords, running longitudinally through
the abdomen, with which they communicate by filaments that encircle
the æsophagus like a necklace. The covering or envelope of the body
is divided by transverse folds into a certain number of rings whose
teguments are sometimes soft, and sometimes hard; the muscles,
however, being always situated internally. Articulated limbs are
frequently attached to the trunk; but very often there are none. We
will call these animals Animalia Articulata, or articulated animals,
in which is observed the transition from the circulation in closed
vessels to nutrition by imbibition, and the corresponding one of
respiration in circumscribed organs, to that effected by tracheæ
or air-vessels distributed throughout the body. In them the organs
of taste and sight are the most distinct; one single family alone
presenting that of hearing. Their jaws, when they have any, are
always lateral.
The fourth form, which embraces all those animals known by the name
of zoophytes, may also be properly denominated Animalia Radiata, or
radiated animals. We have seen that the organs of sense and motion in
all the preceding ones are symmetrically arranged on the two sides of
an axis. There is a posterior and anterior dissimilar face. In this
last division they are disposed by rays round a centre; and this is
the case even when they consist of but two series, for then the two
faces are similar. They approximate to the homogeneity of plants,
having no very distinct nervous system or particular organs of
sense; in some of them it is even difficult to discover a vestige of
circulation; their respiratory organs are almost universally seated
on the surface of the body, the intestine in the greater number is a
mere sac without issue, and the lowest of the series are nothing but
a sort of homogeneous pulp, endowed with motion and sensibility.
DEEP SEA FAUNA
--LORD KELVIN
Nearly all the animals at extreme depths--practically all the
animals, for the small number of higher forms feed upon these--belong
to one sub-kingdom, the Protozoa; whose distinctive character is that
they have no special organs of nutrition, but absorb nourishment
through the whole surface of their jelly-like bodies. Most of these
animals secrete exquisitely formed skeletons, some of silica, some
of carbonate of lime. There is no doubt that they extract both these
substances from the sea-water; and it seems more than probable that
the organic matter which forms their soft parts is derived from the
same source. It is thus quite intelligible that a world of animals
may live in these dark abysses, but it is a necessary condition that
they must chiefly belong to a class capable of being supported by
absorption through the surface of their bodies of matter in solution,
developing but little heat, and incurring a very small amount of
waste by any manifestation of vital activity. According to this view
it seems probable that at all periods of the earth’s history, some
form of the Protozoa--rhizopods, sponges, or both--predominated
greatly over all other forms of animal life in the depths of the
warmer regions of the sea. The rhizopods, like the corals of a
shallower zone, form huge accumulations of carbonate of lime, and it
is probably to their agency that we must refer most of those great
bands of limestone which have resisted time and change, and come
in here and there with their rich imbedded lettering to mark like
milestones the progress of the passing ages.
We find the first and simplest of the invertebrate sub-kingdoms,
the Protozoa, represented by three of its classes--the monera,
the rhizopoda, and the sponges. The monera have been defined as a
distinct class by Professor Ernst Haeckel, of a vast assemblage of
almost formless beings apparently absolutely devoid of internal
structure, and consisting simply of living and moving expansions of
jelly-like protoplasm. The monera pass into the rhizopoda, which give
a slight indication of advance in the definite form of the graceful,
calcareous, shell-like structures which most of them secrete, and the
two groups may be taken together.
The dredging at 2,435 fathoms at the mouth of the Bay of Biscay gave
a very fair idea of the condition of the bottom of the sea over an
enormous area, as we know from many observations which have now been
made with the various sounding instruments contrived to bring up a
sample of the bottom. Under the microscope the surface-layer was
found to consist chiefly of entire shells of Globigerina bulloides,
large and small, and fragments of such shells mixed with a quantity
of amorphous calcareous matter in fine particles, a little fine sand,
and many spicules, portions of spicules, and shells of Radiolaria, a
few spicules of sponges, and a few frustules of diatoms.
In this dredging, as in most others in the bed of the Atlantic,
there was evidence of a considerable quantity of soft gelatinous
organic matter, enough to give a slight viscosity to the mud of
the surface-layer. This gelatinous matter is capable of a certain
amount of movement, and there can be no doubt that it manifests the
phenomena of a very simple form of life.
To this organism, if a being can be so called which shows no trace
of differentiation of organs, consisting apparently of an amorphous
sheet of a protein compound, irritable to a low degree and capable of
assimilating food, Professor Huxley has given the name of Bathybius
haeckelii. The circumstance which gives its special interest to
Bathybius is its enormous extent: whether it be continuous in one
vast sheet, or broken up into circumscribed individual particles, it
appears to extend over a large part of the bed of the ocean; and as
no living thing, however slowly it may live, is ever perfectly at
rest, but is continually acting and reacting with its surroundings,
the bottom of the sea becomes like the surface of the sea and of the
land--a theatre of change, performing its part in maintaining the
“balance of organic nature.”
Living upon and among this Bathybius, we find a multitude of other
protozoa--foraminifera and other rhizopods, radiolarians, and
sponges; and we as yet know very little of the life-history of these
groups.
Many foraminifera of different groups inhabit the deep water, lying
upon or mixed in the upper layer of the globigerina ooze, or fixed
to some foreign body, such as a sponge, coral, or stone; and all of
these are remarkable for their large size.
The few hauls of the dredge which we have already had in deep water
have been enough to teach us that our knowledge of sponges is in
its infancy--that those which we have collected from shallow water
along our shores, and even those few which have been brought up from
deep water on fishing lines, and have surprised us by the beauty of
their forms and the delicacy of their lustre, are the mere margin and
remnant of a wonderfully diversified sponge-fauna which appears to
extend in endless variety over the whole of the bottom of the sea.
The most remarkable new forms are referable to the group which seems
to be in a sense special to deep water, the Hexactinellidæ. One
of the most abundant and singular forms belonging to this order,
Holtenia carpenteri, is an oval or sphere 90 to 100 mm. in height,
with one large oscular opening at the top about 30 mm. in diameter,
whence a simple cylindrical cavity cupped at the bottom passes down
vertically into the substance of the sponge to the depth of 55 mm.
The outer wall of the sponge consists of a complicated network of
the cross-like heads of five-rayed spicules. One ray of each spicule
dips directly into the body of the sponge, and the other four, which
are at right angles to it, form a cross on the surface, giving it a
beautiful stellate appearance. The silicious rays of one star curve
toward and meet the rays of the neighboring stars, and run parallel
with them. All the rays of all the spicules are thickly invested
with consistent semi-transparent gelatinous matter, which binds
their concurrent branches together by an elastic union, and fills
up the angles of the meshes with softly curved viscous masses. This
arrangement of the spicules, free and yet adhering together by long
elastic connections, produces a strong, flexible, and very extensible
tissue. The cylindrical oscular cavity within the sponge is lined
with nearly the same kind of network.
When the sponge is living, the interstices of the silicious network
are filled up both outside and in with a delicate fenestrated
membrane formed of a glairy substance like white of egg, which
is constantly moving, extending or contracting the fenestræ, and
gliding over the surface of the spicules. This “sarcode,” which is
the living flesh of the sponge, contains distributed through it an
infinite number of very minute spicules, presenting the most singular
and elegant forms very characteristic of each species of sponge. A
constant current of water carried along by the action of cilia passes
in by apertures in the outer wall, courses through the passages in
the loose texture of the intermediate sponge-substance carrying
organic matter in solution and particles of nourishment into all its
interstices, and finally passes out by the large “osculum” at the
top. Over the upper third of the sponge a multitude of radiating
rigid silicious spicules form a kind of ornamental frill, and from
the lower third a perfect maze of delicate glassy filaments, like
fine white hair, spread out in all directions, penetrating the
semi-fluid mud, and supporting the sponge in its precarious bed by
increasing its surface indefinitely while adding but little to its
weight.
This is only one of the ways by which sponges anchor themselves in
the ooze of the deep sea. Hyalonema sends right down through the soft
mud a coiled wisp of strong spicules, each as thick as a knitting
needle, which open out into a brush as the bed gets firmer, and fix
the sponge in its place somewhat on the principle of a screw pile. A
very singular sponge from deep water off the Lofoten Islands spreads
into a thin circular cake, and adds to its surface by sending out a
flat border of silky spicules, like a fringe of white floss round
a little yellow mat; and the lovely Euplectella, whose beauty is
imbedded up to its fretted lid in the gray mud of the seas of the
Philippines, is supported by a frill of spicules standing up round it
like Queen Elizabeth’s ruff.
The sponges of the deep-water ooze are by no means confined to
one group. The Hexactinellidæ are perhaps the most abundant, but
corticate sponges even, closely allied to those which look so rigid
when fixed to stones in shallow water, send out long anchoring
spicules and balance themselves in the soft mud; and off the coast of
Portugal Mr. Gwyn Jeffreys dredged in 1870 several small forms of the
Halichondridæ, with long supporting fibrous beards.
From its appearance when brought up Holtenia evidently lives buried
in the mud to its upper fringe of spicules. When freshly dredged, it
is loaded with pale gray semi-fluid sarcode, full of Globigerinæ,
Triloculinæ, and other rhizopods, and covered in our northern
localities with the little ophiurid Amphiura abyssicola, Sars, and
the exquisitely delicate transparent clam, Pecten viterus Chemnitz.
Holtenia extends from the Butt of Lewis to Gibraltar, in from 500 to
1,000 fathoms.
In the Hexactinellidæ all the spicules, so far as we know, are
formed on the hexradiate plan; that is to say, there is a primary
axis, which may be long or short, and at one point four secondary
rays cross this central shaft at right angles. In many of the
Hexactinellidæ the spicules are all distinct, and combined, as in
Holtenia, by a small quantity of nearly transparent sarcode; but
in others, as in “Venus’s flower-basket,” and the nearly equally
beautiful genera Iphiteon, Aphrocallistes, and Farrea, the spicules
run together and make a continuous silicious network. When this is
the case the sponge may be boiled in nitric acid, and all the organic
matter and other impurities thus removed, when the skeleton comes out
a lovely lacy structure of the clearest glass. The six-rayed form of
the spicules gives the network which is the result of their fusion
great flexibility of design, with a characteristic tendency, however,
to square meshes.
Off the Butt of Lewis, in water of 450 to 500 fathoms, we met on two
occasions with full-grown specimens of a species of the remarkable
genus Hyalonema, with the coils in the larger examples upward of 40
centimetres in length.
A bundle of from 200 to 300 threads of transparent silica, glistening
with a silky lustre, like the most brilliant spun-glass--each
thread from 30 to 40 centimetres long, in the middle the thickness
of a knitting-needle, and gradually tapering toward either end to
a fine point; the whole bundle coiled like a strand of rope into
a lengthened spiral, the threads of the middle and upper portions
remaining compactly coiled by a permanent twist of the individual
threads; the lower part of the coil, which, when the sponge is
living, is imbedded in the mud, frayed out so that the glassy threads
stand separate from one another, like the bristles of a glittering
brush; the upper portion of the coil close and compact, imbedded
perpendicularly in a conical or cylindrical sponge; and usually
part of the upper portion of the silicious coil, and part of the
sponge-substance, covered with a brownish leathery coating, whose
surface is studded with the polypes of an alcyonarian zoophyte--such
is the general effect of a complete specimen of Hyalonema.
The genus was first known in Europe by specimens brought from Japan
by the celebrated naturalist and traveler, Von Siebold; and Japanese
examples of Hyalonema sieboldi, Gray, may now be found more or less
perfect in most of the European museums. When the first specimen of
Hyalonema was brought home, the other vitreous sponges which approach
it so closely in all essential points of structure were unknown.
In essential structure Hyalonema very closely resembles Holtenia,
and the more characteristic forms of the Hexactinellidæ. On one of
the Holteniæ from the Butt of Lewis, there was a little accumulation
of greenish granular matter among the fibres. On placing this under
the microscope it turned out to be a number of very young sponges,
scarcely out of their germ state. They were all at first sight
very much alike, minute pear-shaped bodies, with a long delicate
pencil of silky spicules taking the place of the pear-stalk. On
closer examination, however, these little germs proved to belong to
different species, each showing unmistakably the characteristic forms
of its special spicules. Most of them were the young of Tisiphonia,
but among them were several Holteniæ, and one or two were at once
referred to Hyalonema. In two or three hauls in the same locality
we got them in every subsequent stage--beautiful little pear-shaped
things, a centimetre long, with a single osculum at the top, and
the wisp like a small brush. At this stage the Palythoa is usually
absent, but when the body of the sponge has attained 15 mm. or so in
length very generally a little pink tubercle may be detected at the
point of junction between the sponge body and the coil, the germ of
the first polype.
During Mr. Gwyn Jeffreys’s cruise in 1870, two specimens of a
wonderful sponge belonging also to the Hexactinellidæ were dredged
in 374 fathoms in rocky ground off Cape St. Vincent. The larger of
these forms a complete vase of a very elegant form, nearly ninety
centimetres in diameter at the top and about sixty in height. The
sponge came up folded together, and had much the appearance of a
piece of coarse, grayish-colored blanket.
Near the mouth of the Strait of Gibraltar a number of species were
taken in considerable quantity, belonging to a group which were
at first confused with the Hexactinellidæ, on account of their
frequently forming a similar and equally beautiful continuous network
of silica, so as to assume the same resemblance to delicate lace when
boiled in nitric acid. The Corallio-spongiæ differ, however, from the
Hexactinellidæ in one very fundamental character. While in the latter
the spicule is hexradiate, in the former it consists of a shaft with
three diverging rays at one end.
This group of sponges are as yet imperfectly known. They seem to pass
into such forms as Geodia and Tethya; and the typical example with
which we are most familiar is the genus Dactylocalyx, represented by
the cup-shaped pumice-like masses which are thrown ashore from time
to time on the West Indian Islands.
Twelve species of stony corals were dredged in 1869.
From their considerable size, the length and rigidity of their
straggling rays, and their habit of clinging to fixed objects, the
Echinodermata are not very readily taken by the dredge, but they
fall an easy prey to the “hempen tangles.” It is possible that this
circumstance may to a certain extent exaggerate their apparent
abundance at great depths, but we have direct evidence in the actual
numbers which are brought up that in some places they must be
wonderfully numerous; and we frequently dredge sponges and corals
actually covered with them in the attitudes in which they lived,
nestling among their fibres and in the angles of their branches. I
have counted seventy-three examples of Amphiura abyssicola, small and
large, sticking to one Holtenia.
Both on account of their beauty and extreme rarity, and of the
important part they have borne in the fauna of some of the past
periods of the earth’s history, the first order of the Echinoderms,
the Crinoidea, has always had a special interest to naturalists; and,
on the watch as we were for missing links which might connect the
present with the past, we eagerly welcomed any indication of their
presence. Crinoids were very abundant in the seas of the Silurian
period. But during the lapse of ages the whole order seems to have
been worsted in the “struggle for life.” They become scarce in the
newer Mesozoic beds, still scarcer in the Tertiaries, and up to
within the last few years only two living stalked crinoids were known
in the seas of the present period, and these appeared to be confined
to deep water in the seas of the Antilles, whence fishermen from time
to time bring up mutilated specimens on their lines. Their existence
has been known for more than a century; but although many eyes have
been watching for them, until very lately not more than twenty
specimens had reached Europe, and of these only two showed all the
joints and plates of the skeleton, and the soft parts were lost in
all.