The science of life; or the animal and vegetable biology

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

OIKT OK

-Received
Accession No.

Class No.

I. PROTOPHYTES

THAL LOGENS m. ACROGENS

W. ENDOGENS

EXOGENS

I. PROTOZOA

H.RADIATA

IV.ARTICULATA

m.MOLLUSCA

WERTEBRATA

BIOLOGICAL TYPES.

THE

SCIENCE OF LIFE ;

OR,

ANIMAL AND VEGETABLE BIOLOGY.

BY

REV. J. H. WYTHE, A.M., M.D.,

AUTHOR OF "AGREEMENT OF SCIENCE AND REVELATION," "THE MICROSCOPIST," ETC

NEW YORK :
PHILLIPS & HUNT

CINCINNATI :
WALDEN & STOWE.

l88o.

' COI'YRK'.IIT I880, BY

ZEiTJUXTT,
NEW YORK.

UNIVERSITY

PREFACE.

r I "HIS book is written for those who have
J- some elementary knowledge of Physiology.
It gives a general outline of the origin, structure,
typical forms, and functions of living things, so as
to serve as an introduction to the examination of
the objects themselves.

Although a text-book must of necessity be a
compilation of facts, yet many years of practical
experience with the microscope have enabled the
writer to describe many things with the confi-
dence of personal observation. Some of the illus-
trations are original, others have been selected
from Dr. Carpenter's works on Physiology and
the Microscope, T. R. Jones on Zoology, Lind-
ley's Botany, Mac Ginley's Introduction to Biol-
ogy, and other standard works.

It has been the aim of the author to guide the

student through the fundamental principles of
1*

6 PREFACE.

Biology to the contemplation of the vast temple
of animated nature, with its varied compartments
intimately connected with each other, and with
the central one of all, the human type. In every
avenue and chamber and dome of this wondrous
edifice the Christian student recognizes the truth

that " POWER BELONGETH UNTO GOD."
OAKLAND, CAL., January, 1880.

C ONTENTS.

. HAPTlnt PAGE

I. \VMAT is LIFE ? 9

II. LIVING MATTER 26

III. PARENTAGE 40

IV. TISSUE FORMATION 52

V. TYPES OF CONSTRUCTION 72

VI. PROTOPHYTES 84

VII. THALLOGENS 98

VIII. ACROGENS 109

IX. ENDOGENS 122

X. EXOGENS 137

XI. PROTOZOA 161

XII. RADIATA 170

XIII. MOLLUSCA 192

XIV. ARTICULATA 213

XV. VERTEBRATA 239

XVI. THE HUMAN TYPE . . .281

TJHI7BRSIT7

THE

SCIENCE OF LIFE.

CHAPTER I.

WHAT IS LIFE?

Am I but what I seem — mere flesh and blood ?
A branching channel, and a mazy flood ?
The purple stream that through my vessels glides,
Dull and unconscious flows, like common tides.
The pipes, through which the circling juices stray,
Are not that thinking I, no more than they.
This frame, comparted with transcendent skill,
Of moving joints, obedient to my will,
Nursed from the fruitful glebe, like yonder tree,
Waxes and wastes : I call it mine, not nit.
New matter still the moldering mass sustains,
The mansion changed, the tenant still remains ;
And from the fleeting stream, repaired by food,
Distinct, as is the swimmer from the flood.

— ARBUTHNOT.

i. THE term Biology, (from the Greek, bios, life, and
logos, a discourse, or doctrine,) signifies the Science of
Life. It includes the study of all the phenomena of living
beings, both animal and vegetable, in order to discover
the general principles which underlie their origin, for-
mation, varieties, and functions. The special study of
structure is termed Morphology, or Anatomy. The
study of functions is Physiology. The origin, develop-
ment, and arrangement of the varieties of the vegetable
world make up the study of Botany. Zoology considers

io THE SCIENCE OF LIFE.

the various kinds of animals. All these sciences, and
many others, combine in Biology.

To the Christian student Biology affords a multitude
of evidences of intelligent design, proving the universe
to be the product of Supreme Will. It also contains
proof of the reality of spiritual existences, in addition
to physical atoms and physical forces.

2. The cause of difference between the living and the
non-living is the most fundamental question of Biology,
and the answers given to this question by modern
writers depend upon the schools of philosophy to which
they are attached.

Much learning and industry have been employed within
the past few years to teach the system of Monism, or the
theory that all being can be resolved into a single prin-
ciple. Among those who entertain this view, some hold
to materialism, or the development of all forms from
primitive atoms. Others are idealists, conceiving matter
to be identical with force. Others again are pantheists,
holding that mind is the only substance, and that the
universe is an emanation of the universal mind.

The doctrine of rational Dualism, which asserts two
real principles of existence, mind and matter, with their
special endowments and forces, stands in opposition to
all forms of Monism whatever.

Since the dawn of history these speculations have di-
vided philosophers, and learning of all kinds has been
used to maintain the views of either side. Leucippus
and Democritus, the masters of Epicurus, taught the
doctrine of invisible and indestructible atoms, with spon-
taneous motion, as the cause of all things. Anaxagoras

WHAT is LIFE?

and Plato argued for a regulating intelligence, producing
order, so that " the world's activities are reflections of
God's thoughts." The Hebrew and Christian Script-
ures, as well as all other writings which exhibit the
religious beliefs of mankind, Koran or Shaster, King or
Avesta, (the sacred books of Mohammedans and Hindus,
Chinese and Persians,) teach the doctrine of Dualism, or
the distinction between mind and matter.

3. The revival of Monistic philosophy in the last
century has awakened much discussion, and each of the
sciences in turn has been made the arena of conflict.
In Biology, Darwin, Spencer, and Haeckel are arrayed
against Agassiz, Lionel Beale, and M'Cosh, and the con-
test of mind has brought to notice a wonderful accumu-
lation of facts, sufficient, we think, to settle the central
question of philosophy concerning life.

In the present work the facts of Biology are regarded
as .confirmatory of the principles of rational Dualism. In
the judgment of the writer there is no conflict between
science and revealed truth, but such complete agreement
that the facts of science can be best understood and
explained in consistency with that philosophy which re-
ligion has made prevalent in the minds of the majority
of men. Yet the learning and apparent candor of many
Monistic writers entitle them to respect, even if we fail to
agree with them, and truth, which should be the object
of all study, is not aided by epithets or personal acri-
mony.

4. Some scientists ignore the question of the cause of
life, and confine themselves to the physical and chemical
phenomena associated with living things; but this is

12 THE SCIENCE OF LIFE.

quite unsatisfactory. That there are differences between
the living and the non-living will only be denied by the
most thorough partisans of Monism. These differences
depend on something in the living which is absent from
the non-living. In common parlance we call it life, or
life-force. Such a life-force is as necessary to Biology as
gravitation is to Physics, or light to Optics.

Writers who avoid Dualism, or who acknowledge
antagonism to it, have not been able to give a clear
definition of life.

Bichat defines life as " the sum of the functions by
which death is resisted." This is but saying that life
and death are opposite states.

Dr. W. B. Carpenter, although believing in the difference
between mind and matter, speaks of life as " the condi-
tion of a being which exhibits vital actions ; " which is but
another mode of stating that life is a condition or state
of living.

Coleridge considered life as synonymous with " indi-
viduation." This is equivalent to separate existence,
and includes metals, and stones, and all non-living things.

Herbert Spencer defines life as "the continuous adjust-
ment of internal relations to external relations." This
definition will apply to a boiling tea-kettle, a steam-
engine, or a burning candle, as well as to a living thing.

Haeckel declares " that all natural bodies which are
known to us are equally animated, and that the distinc-
tion which has been made between animate and inani-
mate bodies does not exist." This exceedingly bold and
strange statement is rendered necessary by the logical
demands of the Monistic philosophy. In a subsequent

WHAT is LIFE? 13

place we shall examine particularly the differences be-
tween animate and inanimate bodies. (See Chap. II.)

All such definitions and statements evade the real
question : that is, What makes the difference between a
living body and the same body a moment after death ?

5. The cause of life is a mystery only to the mate-
rialist. To the Christian philosopher it is as plainly
revealed as any other fact of nature. The Bible asserts
that life results from the union of a spiritual nature with
the material body. In other words, life is the influence
resulting from the union of matter and spirit ; and this
dualistic theory is the only one which suffices to explain
the phenomena of living things.

Moses declares of man that God " breathed into his
nostrils the breath of life ; and man became a living
soul." In accordance with this view death is every-
where referred to in Scripture as a departure of the
spirit. The medical evangelist, St. Luke, when describ-
ing the resuscitation of Jairus' daughter, says, " Her
spirit came again, and she arose straightway." St. Paul
describes the body as a tent, or house, in which the spirit
may be present or absent. It is also remarkable that
the same Hebrew word which describes man as a "living
soul " is applied to animals in the same history of crea-
tion. Gen. i, 20, 30. They also are living souls.

This view of the cause of life was also held by ancient
Grecian philosophy. Aristotle attributed organization
and vital actions to a series of animating principles,
(psychai^) different in each organized body, and acting
by power derived from the supreme animating principle,
(p/iysis)

14 THE SCIENCE OF LIFE.

M Ciller, the father of modern physiology, substituted
the term " organic force" for that of "animating princi-
ple," and Dr. Prout used the term " organic agent."
The precise term employed is of but secondary import-
ance compared with the dualistic conception, which is
quite satisfactory to the large majority of thinkers.

6. We shall be able to appreciate this subject better
if we consider the life-history of some simple animal.

It is well known that infusions of vegetable or animal
substances contain many living forms of extreme sim-
plicity of structure, called Infusoria. Many such are
found in ponds, or running water, or in the sea. A very
beautiful kind of Infusoria, common among half-decayed
leaves, has received the name of Vorticella, or bell-
shaped animalcule. There are several species, the most
common being known as Vorticella nebulifera. Take up
from a pond a little twig, covered with mold or mucus-
like substance, and place it under the microscope. In
all probability you will see a colony of Vorticellae,
(Fig. i.)

Each animalcule has a glassy, transparent bell, with a
thick lip or rim, fringed with cilia or hair-like projec-
tions. These cilia are sometimes withdrawn, but when
active vibrate rapidly, so as to make a sort of whirlpool
in the water, in the vortex of which smaller animals or
vegetables may be conveyed as food to the interior of
the Vorticella. A number of pellucid spots may be
seen in the body of each animalcule, which were for-
merly regarded as stomachs. Professor Ehrenberg, who
elaborately investigated this class of animal life, gave
the name Polygastrica (many stomachs) to those animal-

WHAT is LIFE? 15

cules which presented this appearance. By feeding with
coloring matter, as carmine or indigo, these stomachs
have been found to be merely excavations in the bio-
plasm, or living matter, which constitutes the body ot

r^iG. i. — a. Colony of Vorticella. b. b. b. Stages of fission, or self-division, c. A sep-
arate individual, d. Encysted state, e. Ruptured cyst emitting gemmules in a mass of
gelar'ne or gum. f. Acineta parasites.

tht: animal. Some of these excavations are extempo-
raneous, but one cavity is persistent, and pulsates in a
peculiar manner, so that it has received the name of
contractile vesicle. Each glassy bell is attached to the
twig by a slender thread, and usually swings to and fro
in the water with the thread or footstalk fully stretched,
and the cilia moving rapidly. Frequently, however, and
especially on some unusual jar, or other cause of alarm,
the thread contracts in the form of a spiral, and the cilia
are withdrawn into the substance of the bell.

These Infusoria usually increase by self-division. The

1 6 THE SCIENCE OF LIFE.

globular bell becomes first flattened, then notched, and
lastly divided. As soon as division takes place there are
distinct motions in the separate individuals. In one of
them the cilia are absorbed, and new cilia appear on the
side next to the footstalk. The motions of the new cilia
form a current sufficient to detach the newly-formed
bell, which becomes isolated, swims away, and develops
a new stalk, after fixing itself in a new place.

Another mode of increase sometimes occurs, in which
the animalcule seems to pass through a sort of chrysalis
state. It becomes encysted, like the primitive forms of
vegetables. It is first rounded, then a sort of gelatinous
secretion hardens into a case, protecting the interior
from antagonizing cold, etc. ; then the encysted body
breaks up into nuclei, or separate spots, and afterward
into numerous gemmules, or small germs, which are set
free by the bursting of the envelope, and swim away to
grow into new individuals.

During the encysting process the Vorticella often ap-
pears like a globular pincushion with pins sticking in it.
This is now known to be caused by a parasite, the
Acineta, which sends forth a projecting arm into the
body of its host to absorb its fluid nutriment.

7. I have selected the Vorticella for a first lesson on
Biology because it is quite common, and simple enough
for study. What can we learn here of life-force? Is
there such a thing as life-force ? Is there a difference
between the living Vorticella and the dead twig it rests
upon? Some philosophers, as we have seen, declare
that there is no difference. The old astrologers used to
say that all things were living, and the teachers of an-

WHAT is LIFE? 17

cient magic and heathen philosophy taught a universal
world-spirit, which is the life of all things. To this pan-
theistic theory the adherents of the dogma of the me-
chanical origin of the universe naturally gravitate. It is
more consistent with common sense and true philoso-
phy, as well as with the facts of science, to maintain an
essential difference between the animate and the inani-
mate. Can the dead twig move spontaneously, like the
living animalcule ? Does it assimilate food and repro-
duce itself like the Vorticella ? Or can a dead animal
respond to natural stimuli like the living ? Not a single
fact has been brought forward to prove the identity
of the living and the non-living. It is at best on-
ly a theory. "On the other hand," says Dr. Beale,
" thanks to the steady progress of minute investigation,
unnoticed by popular writers, and perhaps unknown
to them, the conclusion that life of every kind is dis-
tinct from ordinary forces is at this time more strongly
supported by facts, and more firmly established than it
ever was." *

8. In order to defend the Monistic philosophy, and
the identity of animate and inanimate objects, some
argue that matter has no existence as such, but that
each atom is only a center of force. They thus repu-
diate the charge of materialism, since they teach that
every thing is spirit. This is a most subtle and in-
genious method of defense, yet is just as baseless as the
grosser Monism, which considers all to be material.

Newton's law, of gravity being in direct ratio to the
mass of matter, that is, to the number of atoms in the

* Beale's " Protoplasm."
2*

1 8 THE SCIENCE OF LIFE.

mass, proves atoms to be real physical existences. All
chemical science is based on the doctrine that atoms and
molecules have weight, definite proportions or relations,
and hence definite form. The law of Avogadro and Am-
pere, as it is called, that " equal volumes of all substances
when in the state of gas, and under like conditions, con-
tain the same number of molecules," is confirmed by all
chemical experiments, and necessarily implies the reality
of atoms and molecules. Our own consciousness of
matter, also, the sense of otherness which pertains to
our knowledge of the objects of sense, is as reliable as
any other knowledge. We know the otherness, as well
as the weight and inertia of matter by the same faculties
by which we know that two and two make four, and not
five. The obvious distinctions between the living and
the not living are all proofs of Dualism.

9. As to the theory that atoms have a physical and a
spiritual side, by which opposite qualities are exhibited,
it carries its own refutation, since it is plainly impossible
for a healthy mind to believe that contrary properties can
inhere in any thing at the same time. Mr. Joseph Cook
has pertinently said : " If matter is a double-faced unity,
having a spiritual and a physical side, there must co-
inhere in one and the same substratum extension and
the absence of extension, inertia and the absence of iner-
tia, color and the absence of color, form and the absence
of form. To assert that these fundamentally antago-
nistic qualities of matter and mind not only inhere, but
co-inhere, in one and the same substratum, is to assert
that a thing can be and not be at the same time and in
the same sense. This limitless self-contradiction wrecks

WHAT is LIFE? 19

in this age, as it has wrecked in every age, the pretense
that there is but one substance in the universe.*

10. The continuance of life in an organism composed
of new atoms, after the old atoms have been cast off,
proves that the cause of life does not spring from the
atoms themselves. An atom of oxygen or hydrogen,
endowed with life to-day, as part of an organized mole-
cule of a Vorticella, or as part of our own bodies, may
be to-morrow released from its vital connections, and be
transported, as water or air, to remote parts of the globe.
It may form part of the gigantic Sequoias of the Sierras,
the Cinchona-trees of the Andes, or the Rhododendrons
of the Himalayas. Before the death of the original
organism, or the tree it next served, that atom of oxy-
gen or hydrogen may be again discarded, and pass into
the germ-cell of an animal, or become part of one of the
tissues of a man in a distant part of the world. It is
evident that that atom did not produce the life with
which it was first associated. What may happen to one
atom may happen to all the atoms of an organism. In
active living beings this actually does happen, so that all
the atoms of a living body become disconnected, and
return to the inorganic world, or go to serve other or-
ganisms, while other atoms take their places, yet the
organized body lives on. Its life depends not on the
new atoms, for the body was animate before these atoms
came ; nor does it depend on the old atoms, for it con-
tinues after they have gone. It must, therefore, depend
upon something different from the material atoms. As
matter and spirit are the only objects of thought pos-

* Cook's " Biology," p. 227.

20 THE SCIENCE OF LIFE.

sible to us, and as life does not depend on matter, it
must depend on spirit. If existence and activity con-
tinue after the removal of the original matter, as we
have seen, they may also continue after all matter is
removed. Continued spiritual existence is certainly con-
ceivable, and in view of the endowment of new atoms
by the vitalizing force, we must admit it to be probable,
even after the material of the organism is all destroyed.

The cause of life is more than matter and physical
force. It uses both matter and force for its own ends
and after its own laws. " Its power of control over
matter and physical laws proves its superiority over, and
its distinction from, matter. Life is matter's master,
not its slave. Life is a workman, a builder, a chemist ;
and each organized being has its own appropriate life,
the result of the union of the spiritual and the material
in itself." *

ii. The view we have taken of the difference between
the animate and the inanimate objects of creation is one
which is growing in favor with the principal workers in
biological science. Dr. Beale's discoveries and gener-
alizations in Histology have done much to arrest the
skeptical tendencies of scientists, and in one of Mr.
Huxley's latest utterances he acknowledges that " the
properties of living matter distinguish it absolutely from
all other kinds of things," and that " the present state
of knowledge furnishes us with no link between the liv-
ing and the not-living." f The last-named anatomist
names the distinctive properties of living matter as fol-

* " Agreement of Science and Revelation," by the Author.
f Huxley's "Anatomy of Invertebrated Animals."

WHAT is LIFE? 21

lows: i. Its chemical composition; 2. Its universal dis-
integration and waste by oxidation, and its concomitant
reintegration by the intussusception of new matter ;
3. Its tendency to undergo cyclical changes.

Dr. Beale shows that " no relation can be established
between the chemical or other material properties of
different kinds of living matter that will in any way ac-
count for the different results as regards development
and formation. The different powers or properties of
the particles cannot be due to difference of chemical
composition. All living particles consist of compara-
tively few elements, and no differences in the propor-
tions of these would enable us to explain the different
results of the act of living.

" This wonderful stuff, which is the first state of every
thing that has life, splits up when it is destroyed into
a few chemical compounds, from the study of which,
however, chemists have hitherto failed to arrive at any
conclusion as regards the atomic relations of the com-
ponent elements of the matter during life. Neither, as
far as has been ascertained, is there any constant rela-
tion between the volume, or kind, or aggregation of the
matter which is the seat of the manifestation of the vital
power and the form of living being that is to be evolved
from it. Man's matter is no more elaborate, no more
complex, no more beautiful, than dog's matter or sheep's
matter ; but it is in the power, not in the matter, that
we must look for the cause of the remarkable difference
of the results. Insignificantly in matter, but transcend-
ently in power, does the man-germ differ from the dog-
germ. Wonderfully different power may be transmitted

22 THE SCIENCE OF LIFE.

by particles of matter that resemble one another in
every particular that can be ascertained." Again : "It is
by the transmission of power to matter, rather than by
the bodily transference of millions of particles of matter
having particular properties and detached from matter
having similar properties, that inheritable peculiarities
are handed down from parent to offspring. And it must
be borne in mind that structure-forming capacity, which
is not even rendered evident until forty or fifty years
shall have passed since the original germ-speck origi-
nated in the parent, may affect pounds weight of matter,
not one grain of which will be acquired until long after
every atom of that primitive speck shall have ceased to
live and have been removed from the organism. Matter,
with its forces, continually comes and goes, while power
only remains unimpaired and preserves its identity.
Power has been handed down — has been transferred
from old particles to new particles of matter; but the
original matter — nay, in the case of some of the largest
animals, hundreds weight of matter — must have come
and gone, while the original power remained." " Vital
power works according to predetermined order, and the
results of its working are seen in different consequences,
at different periods of its action." " Vital power pre-
pares for far-off events, and acts as if phenomena, not to
occur until after the lapse of a considerable time, had
been from the first foreseen. Vital power suspends the
action of chemical affinity, and piles material particle
above particle, the force of gravity notwithstanding."*
12. Sometimes life remains dormant from lack of ap-

* "Protoplasm," by Dr. L. Beale.

WHAT is LIFE? 23

propriate stimuli, or conditions, or from sonic unexplained
peculiarity. This proves those philosophers to be in er-
ror who imagine that molecular change is essential to
life. The seed which has been held in the hand of an
Egyptian mummy perhaps for thousands of years, re-
tains the vital power, and may sprout under favorable
conditions. The wheel animalcule (Rotatoria) has been
dried and resuscitated many times in succession, and
Messrs. Drysdale and Dollinger have proved that the
germs of Infusoria cannot be destroyed by the heat of
boiling water, but live when the thermometer shows a
heat of 300° F. These resisting germs, floating in the
air, will soon revive on the accession of moisture.

13. Death occurs when the cause of life is removed.
Life is not synonymous with spirit, but is peculiar spir-
itual influence on matter ; the result of the union of cre-
ated spirits and elemental matter. When the spiritual
essence ceases to act upon the matter of the organism
we say the body is dead, and then disintegration and
chemical decomposition succeed. There is a two-fold
death — the death of the organism as a whole, called so-
matic, or bodily death, and molecular death, or the loss
of vital activity in the molecules of the body. Life be-
gins in a single molecule of bioplasm, and is propagated
as a force more or less modified from molecule to mole-
cule, or from cell to cell, as flame proceeds from one
combustible substance to another, or as magnetism is
disseminated by the action of a single magnet through
one bar of steel after another.

Molecular death is a continual phenomenon of life
during its activity. It is arrested in dormant life, and

24 THE SCIENCE OF LIFE.

is far from being so constant an attendant upon all the
actions of the body as some have taught, yet it goes on
with great rapidity and uniformity. The bioplasts, or
living particles, of each tissue in the body are changed
into formed material, and then pass into decay, while
other bioplasts take their places and keep up the active
dance of life. When the spiritual cause, or origin, of
vital phenomena is removed, the molecular activities of
the body do not all cease at once, but gradually. Hair
will continue to grow on a corpse, and the secretion of
rattle-snake poison, or of other glands, continues for a
short time after death. Indeed, the circulation of blood
has been witnessed in a section of mouse's kidney some
time after it had been removed from the body. Yet,
uninfluenced by the energizing spirit, the vital activities
gradually cease, and decomposition ensues.

14. To return to our example from the Infusoria, the
life-history of the Vorticella demonstrates both the spir-
itual origin of life and the work of a Supreme Intelli-
gence. The evidence of design in its construction is
quite apparent. The extensile threads and vibsatile
cilia have, plainly enough, an object. They subserve
prehension of food and the preservation of existence.
Even the contractile vesicle, whose exact purpose we do
not know, impresses our minds with the fact that it serves
some purpose. This design is connected with some-
thing different from the material atoms of the organism,
but which controls those atoms, since there is foresight
of future changes, and provision for future changes in
the life-history which will occur after the removal of all
the present material. The self-division of the Vorticella,

WHAT is LIFE' 25

the formation of new cilia, the preparation for increase
by the encysted form, the division into nuclei and gem-
mules, are all examples of this, analogous to the forma-
tion of new structures in the higher animals. The power
to produce these changes is not material but spiritual.

15. Thus our first lesson in Biology brings us to the
confines of a spiritual world. We look across the gulf
which philosophy and science cannot bridge over except
by revealed truth, but the telescope of faith can see re-
alities on the other side as numerous, as diversified, and
as true as the objects of sense which can be weighed and
measured by our physical instruments. We see also the
care and providence of a Supreme Creator. Astronomy
adds emphasis to the Psalmist's declaration, "The heav-
ens declare the glory of God; and the firmament showeth
his handy-work." And Biology indorses the sentiments
of his eloquent utterances respecting living creatures :
" O Lord, how manifold are thy works ! in wisdom hast
thou made them all : the earth is full of thy riches. So
is this great and wide sea, wherein are things^ creep-
ing innumerable, both small and great beasts. There
go the ships : there is that leviathan, whom thou hast
made to play therein. These all wait upon thee ; that
thou mayest give them their meat in due season. That
thou givest them they gather : thou openest thine hand,
they are filled with good. Thou hidest thy face, they are
troubled : thou takest away their breath, they die, and
return to their dust. Thou sendest forth thy spirit, they
are created: and thou renewest the face of the earth.
The glory of the Lord shall endure forever : the Lord
shall rejoice in his works."

26

THE SCIENCE OF LIFE.

CHAPTER II.

LIVING MATTER.

You may bury me as you choose, if you can only catch me. But you will
not understand me when I tell you that I, Socrates, who am now speak-
ing, shall not remain with you after having drunk the poison, but shall de-
part to some of the enjoyments of the blest. You must not talk about
burying or burning Socrates, as if I were suffering some terrible operation.
Such language is inauspicious and depressing to our minds. Keep up your
courage, and talk only of burying the body of Socrates ; conduct the burial
as you think best and most decent. — PLATO'S Phado.

1. THE only unexceptionable characteristic of living
bodies is the possession of living tissue, or bioplasm. This
may be present alone, as in the simple animal and veg-
etable forms, or it may exist in association with structure
which has been formed by it, and hence called formed
material. The bioplasm is nourished by pabulum which
is generally furnished in fluid form.

2. The old division of bodies into organized and un-

organized—the for-
mer having organs,
or distinct parts,
with definite struct-
ure, and of special
use — is no longer
applicable, since
there are some liv-

FIG. ..-AmcAaprincepsX.so. In various shapes.

have no organs. The A mceba princcps, Fig. 2, one of the
most elementary animal forms, is composed of a jelly-

LIVING MATTER. 27

like homogeneous bioplasm, capable of indefinite exten-
sibility and of indefinite use. It is so constantly alter-
ing its outline that it does not retain the same shape for
two successive minutes. It obtains its food by flowing
around it, and digests by direct absorption.

3. Of such simplicity of structure are all the primitive
forms of vegetable and of animal life, while in bone, ( ar-
tilage, flesh, skin, or any other structure of the higher
animals, we find such simple, jelly-like, living matter, or
bioplasm, similar in appearance to the Amoeba, scat-
tered in minute particles all through the tissue, and
careful observation will show how this living matter
is transformed into the formed material of the several
tissues.

4. All animals and vegetables have originated from
minute particles of such bioplasm. Every dog, horse,
man, whale, jelly-fish, oak, cedar, grass, sea-weed, etc.,
began its existence as a particle of bioplasm. And
every tissue and organ, no matter what its form or func-
tion, was built up by similar living matter.

5. In the lowest type of animal life (the Rhizopods)
the vital operations are carried on without any special
organs, as we have seen in the Amoeba ; a little particle
of jelly-like bioplasm, changing itself into a variety of
forms, laying hold of food without members, swallowing
it without a mouth, digesting it without a stomach,
moving without muscles, while the mere separation of a
fragment of this jelly, however small, is sufficient to
originate another and independent living creature, re-
taining, or rather repeating, all the characteristic endow-
ments of the original mass. In the higher animals,

28 THE SCIENCE OF LIFE.

although the first bioplasmic particle subdivides itself
into an aggregation of similar particles or cells, yet there
soon appears a structural differentiation of organs for
special uses, which is more elaborate and heterogeneous
as the type approaches the human structure. A single
cell or living particle, however, in any structure is, to all
intents and purposes, a living thing, and possesses pow-
ers of assimilation, growth, and reproduction, altogether
different from the mineral or non-living body.

6. Living matter, or bioplasm, may be considered
physically as a peculiar compound of the chemical
elements — carbon, oxygen, nitrogen, and hydrogen,
called by Mulder Proteine, and by Mr. Huxley and the
German histologists Protoplasm, or the physical basis of
life. It is nearly identical with Albumen. So far as is
known, this combination of elements is always the prod-
uct of pre-existing, living matter. It has never been
produced in the laboratory, and if it were possible for a
chemist to manufacture albuminoid matter, or proto-
plasm, it would be dead protoplasm, and not bioplasm,
and would be destitute of vital properties. Other con-
ditions are necessary to vital phenomena besides com-
bination of material elements. Light, heat, electricity,
and moisture are all necessary conditions ; nor these
alone, for with all these existing and active, the proto-
plasm may not live. Some other factor is essential to life
besides matter and physical force, as we said in the last
chapter. The term bioplasm is well applied to express
matter in its living state, while protoplasm should be
restricted to the material itself.

7. The essential phenomena of living matter next

LIVING MATTER. 29

claim our attention ; or, What can a living thing do
which the non-living cannot ?

i.) All living things have spontaneous motion. The
non-living are passive, and only move by the compelling
agency of some external force, but the force which
moves living matter is a force which is inherent, and
cannot be explained by physical laws. Living matter
has primary energy, and can overcome inertia, but the
non-living are unable to originate motion. The spon-
taneous motions of bioplasm, or living matter, are
molecular, amoeboid, or wandering.

a. Molecular movement. This must not be con-
founded with what has been called Brunonian motion,
from Dr. Robert Brown, who first described it in 1827.
The latter is a sort of vibration in small particles sus-
pended in fluid, and is supposed to be caused by cur-
rents formed by heat or evaporation. In the molecular
movements of bioplasm each particle of the mass seems
to be independent of the rest. As the passengers in a
crowded street may go the full length of the street, or
turn back, or stop and double as many times as they
wish, so do the particles move in the mass of bioplasm.
Up, down, across, backward, and in all directions— even
through each other — do these molecules move, each im-
pelled by its own inherent energy.*

b. Amoeboid movement receives this name from its
resemblance to the notions of the Amoeba, described in
the present chapter, Sec. 2. The shape is continually
changing, by a portion of the body being projected from
the mass, or retracted, or altered in form.

* Strieker's " Manual of Histology."

30 THE SCIENCE OF LIFE.

c. Wandering movement is a modification of the latter
form. A portion of the bioplasm is projected forward,
and along this temporary arm, or bridge, the semi-fluid
molecules flow along, and accumulate at the farthest
end. In this manner the white cells of blood, which are
particles of bioplasm, wander out of the vessels, perhaps
by means of stomata, or holes, in the sides of the vessels,
into those tissues of the body where they are needed,

FIG. 3. — Clot of Frog's Blood, with Migrating White Blood-cells.

Fig. 3. These motions are wholly unlike any which
occur in lifeless material.

2.) Another essential property of bioplasm is growth.
The term growth does not mean accretion or addition
of material, nor increase of size. A piece of chalk, or a
bank of mud, or any non-living thing, may increase in
size by additions to its material. Growth in a living
thing is different. It is enlargement by nutrition, and
depends on inherent motion. In Chap. I, Sec. 13, it was
stated that hair would grow on a corpse, but the term
grow was used in a popular, and not scientific, sense.
Hair is not a living part of the body. Hair or nails may
be cut or destroyed without sensation or impairment of
the body. They consist of scales of formed material,

LIVING MATTER. 31

pushed forward by the growth of bioplasm behind them.
If you pull out a hair or nail, you reach the quick — that
is, the living or sensitive part. We thus see that some
parts of our body are alive, and others in a non-living
state. The formed portions never grow, but the bio-
plasm, or living matter, grows. The growth of living
matter is by appropriation and transformation. Bio-
plasm " alone, of all matter in the world, moves toward
lifeless matter, incorporates it with itself, and communi-
cates to it, in some way we do not in the least under-
stand, its own transcendentally wonderful properties."
This motion and incorporation and endowment consti-
tute growth.

" The rootlets of the plant extend themselves into the
soil because the living matter at their extremities moves
onward from the point already reached. The tree grows
upward against gravity by virtue of the same living
power of bioplasm. In every bud portions of this living
matter tend to move away from the spot where they
were produced, and stretch upward and onward in ad-
vance. No tissue of any living animal could be formed
unless the portions of bioplasm moved away from one
another." *

3.) Living matter has also the power of nutrition, or
assimilation by selection. As this is connected with
growth, we might have considered it under that head,
but since writers of the mechanical or materialistic school
attempt to account for it on physical or chemical princi-
ples, we deem it best to examine it separately.

The non-living always enlarges by accretion from sirn-

* Beale's " Bioplasm."

32 THE SCIENCE OF LIFE.

ilar material ; the living tissue takes into its interior ma-
terial which it transforms out of pabulum, which is foreign
to its own structure, while at the same time it discards
such molecules or atoms as are unfit for further use.

The chemical composition of the various tissues of the
body cannot be found in the blood, or pabulum, which
nourishes the tissues, but results from metamorphosis, or
transformation, by means of the bioplasts. Endosmose,
or the physical property by which fluids pass through
membranes, or gummy matters, will not account for it,
since in the latter there is no change of material, while
in nutrition there is rearrangement of the atoms in the
tissue-molecules.

Nutrition has sometimes been compared with crystalli-
zation, but crystallization is a deposit of material from a
solution of similar substance, and is altogether different
from nutrition by transformation and selection.

Nutrition has also been compared with a chemical
phenomenon called catalysis. In this, chemical change
takes place because of the presence of a substance which
remains itself unaffected, as when spongy platinum in-
duces the combination of oxygen and hydrogen gases.
In catalysis the third substance neither gives nor takes
from the excited body, but in nutrition the living matter
itself selects appropriate chemical elements from its pab-
ulum, dissolving their former affinities, and recembining
them in a manner which no non-living substance can do.
There is no third substance present which is known to
us, and all the phenomena are peculiar to living matter,
or bioplasm.

4.) Bioplasm can also transmit vital power to its prog-

LIVING MATTER. 33

eny. This property will be considered more in detail in
the next chapter, on Parentage.

8. The peculiar relations and changes of the chemical
elements in bioplasm prove it to possess some power
different from not-living matter, whose actions or results
no chemistry can predict. We have said that bioplasm
consists chejmically of oxygen, hydrogen, carbon, and
nitrogen. Other unessential elements may also be pres-
ent in some cases. But we cannot tell how these ele-
ments are combined, if, indeed, they are combined at all
in the proper sense of that word. As all bioplasm pre-
sents the same appearance, although differently formed
material results from its transformation — different in
physical properties and in chemical composition — as
muscle, nerve, bone, etc., it is probable that the ele-
ments do not combine at all as in inorganic matter, but
that the ordinary affinities are suspended or modified
by vitality.

Bioplasm is a semi-fluid substance, yet it will not
freeze at 32° F., as water does, showing that in this re-
spect it is different from water.

Bioplasm is in a state of constant molecular change,
or unstable equilibrium, since it is constantly receiving
pabulum and transforming itself into formed material,
so that it is doubtful if chemical combination is possible
during life, the atomic activities being too transitory for
combination.

When change takes place from bioplasm into formed ma-
terial combination occurs, but the formed material is not
living tissue, or bioplasm. The life is gone. It is dead,
as if it had never formed part of an organism, although

34 THE SCIENCE OF LIFE.

it may have acquired special properties, as the elasticity
of muscle, or the conducting power of nerve tissue.

If the change referred to occurs suddenly, that is, if
the life of bioplasm is suddenly destroyed, the result is
water, albumen, fat, and sometimes fibrin, and certain
salts, as chloride of sodium, etc.

In slower transformations, which are equivalent to
slow molecular death, different materials result, as fat,
sugar, milk, biliary acids, etc. Free oxygen is some-
times absorbed, and very complex compounds result,
often baffling analysis.

Physiological Chemistry has traced many of the re-
sults of changes in formed material, but the composition
and physical surroundings of germinal or living matter
will not indicate the nature of its transformations nor its
function. No one can tell whether a particular bioplast
belongs to a vegetable or an animal, whether it will form
ar eye or a finger, a nerve or a piece of bone, nor whether
its function shall be secretive, excretive, elastic, or con-
ductive. Nothing but observation can tell its future life-
history.

9. Although all bioplasm has powers or endowments
which transcend all physics and chemistry, and which
can only be accounted for by that dualistic philosophy
which acknowledges the reality of both matter and
spirit, yet " all flesh is not the same flesh." There is an
original and essential distinction between bioplasts.
The bioplasm of a fungus never produces a fish, nor that
of a butterfly a man. This will be fully discussed in the
chapter on Parentage. Yet it is no easy task to dis-
criminate between living forms, especially in what are

LIVING MATTER. 35

called the lower orders. It is difficult to distinguish in
all cases between animals and plants. In the simpler
kinds the characters touch and dissolve into each other,
so that no exclusive definition is possible. Some natur-
alists think that there are organisms which at one period
of life are vegetable, and at another animal.

10. If we consider their origin, both animals and
plants begin life as a small particle of bioplasm. In
plants this forms an ovule, with wall of cellulose, and
in animals it becomes an ovum, or egg, with wall of al-
buminous matter.

11. As to form, we have no means of separating
animals and plants. The zoospores of Algae are like
Infusoria. Sea-mat

(Flustra) and Sea-
moss (Fig. 4) (Poly-
zoa) are like Sea-
weeds, (Algae,) Cor-
als and Actiniae are
like flowers.

12. In chemical
composition, as a
rule, plants are des-
titute of, and ani-
mals are largely

Supplied With ni- F,G.4.-SertulariaOPerculata.

trogen. Yet there are some animal structures without
nitrogen, and some vegetable structures with it. Cellu-
lose, (woody fiber,) generally found in vegetables, is
wanting in the Fungi, and is found in the covering of
Ascidians, (Sea-squirts.) Starch, under the name of

36 THE SCIENCE OF LIFE.

Glycogen, is found in the liver and in the brain. Chlo-
rophyll, which makes the leaves of vegetables green,
is found among animals, as in Stentor, (the trumpet-
shaped animalcule,) and in Hydra viridis, (the green
hydra.)

13. As to locomotive power, bioplasm is essentially
active, as I have described, both in plants and animals.
The zoospores of Algae are covered with cilia, and move
in water like animalcules. Motion is common among
Diatoms, Desmids, Oscillatoria, and other classes of
plants, while Sponges, Corals, Oysters, and Barnacles
are largely destitute of locomotive power.

14. With respect to food, plants live generally on min-
eral or inorganic matter, chiefly water, carbonic acid, and
ammonia, while animals require ready-made organic
compounds to support life. Thus plants manufacture
and animals consume organic pabulum. Yet Fungi,
which are generally classed with vegetables, feed as
animals on organic matters, and insectivorous plants, as
Darwin has shown, feed on animals.

15. Animals generally possess sensation, conscious-
ness, and volition, yet there is a kind of sensation in the
sensitive plant, Venus' fly-trap, etc., and something like
volition in zoospores, or they would often collide in the
active dance they keep up. Plants need rest as well
as animals. Both have their epidemics, poisons, and
remedies.

16. If we admit a dualism, or spiritual cause of life, in
vegetables, as well as in animals, it does not prove them
immortal. Immateriality does not imply immortality.
Existence, spiritual or material, depends on the will of

ER. V

LIVING MATTE

the Creator, and we can only know the future as he has
revealed it.

" Heaven from all creatures hides the book of Fate,
All save the page revealed — the present state."

17. Our study thus far impresses us not only with the
truth that all living things manifest a dualism, but also
that all living are intimately related. Not that all come
from a single germ, or from a few germs, but that ani-
mals and plants form, after some sort, a common family.
From the great Father and Fountain of life all living
things proceed, and their existence and endowments are
according to his will. Immaterial, or spiritual existen-
ces weave for themselves a beautiful garment from the
inorganic world. The plant bioplasm appropriates min-
eral matter, with carbonic acid, water, and ammonia,
and by a wonderful vital chemistry transforms it into
organic compounds, as starch, sugar, gum, albumen, etc.
These compounds afford pabulum to animal bioplasm,
and are transformed to blood, muscle, nerve, and other
complex animal substances. After these transformed
products have served the purposes of animal life they
are discarded, and return again to the mineral world.
Thus the wonderful wheel of life revolves from age to
age under the watchful care of divine Providence.

1 8. The intimate relations of living things may find a
mathematical illustration in the logarithmic spiral, such
as is described by a ship sailing N. E. at an angle of 60°
from the pole. It is the spira mirabilis of Jas. Bernou-
illi, who desired one to be engraved on his tomb, with
the motto : *" Eadem mutata resurgo " — " I rise the same,
though changed." It is a spiral which has the same

38 THE SCIENCE OF LIFE.

character in all its parts, and which may continually de-
crease in the size of its windings without coming to a
point, or increase the number of its convolutions to in-
finity. Such a spiral may illustrate the continuity, yet
varying amplitude, of creation. We may trace the pro-
gressive windings of creative power from the motions of
inorganic bodies in space to the motions of bioplasm in
the vegetable world and to the higher nerve-structures
of animal life. In all organic matter we see the work-
manship of the same Great Artist :

" Lo ! on each seed within its slender rind
Life's golden threads in endless circles wind ;
Maze within maze the lucid webs are rolled,
And, as they burst, the living flame unfold."

In exact truth, however, each widening circle of crea-
tion exhibits some new and higher form of creative
power and skill. The circle widens, and is also in an-
other plane. Something has pushed forward the center.
Every spiral requires a progressive force, as well as a
centripetal and centrifugal one. Each specialization —
either elevation of type or specific difference — involves
new force-expenditure. Certain factors have been suc-
cessively added. First, we find inorganic matter, of
many kinds, or of a single kind. Next, the physical
forces, so-called, but really the activity of a personal
Creator on the matter he has formed. Then we find
life, or the activities in matter of created spirits in most
wonderful gradation. Rising to another plane we find
added to this life mind-force, or intelligence. Still
higher we find spirit, properly so-called, possessed with
moral properties, giving dignity to men and angels.

LIVING MATTER. 39

Yet the spiral is not broken, it is but expanded, and the
analogies and relations have a distinctive similarity,
since they are equally the work of one God and Creator
of all. As the physical forces, by attraction and vibra-
tion, and conservation, arrange the cosmos, or physical
universe, so the various bioplasts weave the living tis-
sues for the living creature — the microcosmos — and so
the conscious acts of our spirits weave the character of
our future life.

40 THE SCIENCE OF LIFE.

CHAPTER III.

PARENTAGE.

We must get rid of all these complications of an erring philosophy, this
floating chaos of mist and phantasms, and return to the Natural Realism,
which all men have been learning from their first hours of childhood, and
can never unlearn, before a science of Physics can be really founded. Its
first principle is that we are real persons, living amid a real world of ma-
terial objects distinct from ourselves. And this double truth leads upward
to One who is the cause both of matter and mind, the Supreme Reality,
who dwells in light inaccessible, but who can reveal himself, and has re-
vealed himself, in love and mercy to the souls he has made. — Modern
Physical Fatalism, by T. R. BlRKS.

1. Two theories divide the learned world respecting
the genesis of living things ; the doctrine of parentage,
or the descent from living creatures each created " after
his kind," and the theory of spontaneous generation of
the living from the non-living, and the transmutation of
one kind of living beings into another. The first theory
is sometimes called the doctrine of Creation, the latter
that of Evolution.

2. The word Evolution simply means to unfold, and
may be used to express the life-history of individuals or
of species, or the development of the plans of the Crea-
tor in the natural world. To such a meaning there
would be no objection by any one, but as it is generally
understood to mean the mechanical or monistic view of
the universe, which ignores a Creator, and teaches the
eternity of substance, the invariability of law, and the
transmutation of living beings, its use should be re-

PARENTAGE. 41

striated to that view. Any other application of it leads
to confusion of thought.

3. There is nothing new in the modern doctrine of
Evolution. Among the Greeks, Leucippus, Democritus,
and Epicurus taught that all forms and phenomena came
from the spontaneous motions of atoms, and this view,
in all probability, was a product of older Indian pan-
theism.

Modern upholders of transmutation differ from each
other greatly in the details of the theory. Some are
atheistic, or agnostic, leaving the Creator entirely out of
view. Among these, some teach, like Lamark, the self-
elevation of species by appetency, or desire, use, and
effort. Others, as Darwin, Haeckel, and many late writ-
ers, teach what is called natural selection with spontane-
ous variability, or the survival of the fittest. Others
again, as Draper and Spencer, teach modification of
species by the surrounding conditions. Some evolution-
ists are deistic, like Owen and Mivart, and teach a pre-
ordained succession, under internal force or innate
tendency ; or, as Morell and Murphy argue, evolution
by unconscious intelligence. In opposition to these
views the majority of naturalists of this and the past age
hold to the doctrine of parentage, and deny the change
or transmutation of species, although admitting a cer-
tain amount of physical variability, producing races or
varieties. Among these may be named Linnaeus, Cuvier,
Agassiz, Dana, Guyot, M'Cosh, Balfour, Dawson, Milne,
Edwards, and Seelye.

4. The acknowledged ability of Agassiz in regard to

all matters connected with natural science entitle his

'4*

42 THE SCIENCE OF LIFE.

opinions to careful consideration. He says : " It is my
opinion that naturalists are chasing a phantom, in their
search after some material gradation among created be-
ings, by which the whole Animal Kingdom may have
been derived by successive development from a single

germ, or from a few germs It is contradicted by the

facts of Embryology and Palaeontology, the former show-
ing us norms of development as distinct and persistent
for each group as are the fossil types of each period re-
vealed to us by the latter." " If they are linked together
as a connected series, then the lowest Acaleph should
stand next in structu/e above the highest Polyp ; and
the lowest Echinoderm next above the highest Acaleph.
So far from this being the case, there are, on the con-
trary, many Acalephs which, in their specialization, are
unquestionably lower in the scale of life than some
Polyps, while there are some Echinoderms lower in the
same sense than many Acalephs." He shows that the
same principle applies to classes in other types: "There
are some members of the higher classes that are inferior
in organization to some members of the lower classes."
The same thing is true in Embryology : " A Vertebrate
never resembles at any stage of its growth any thing but
a Vertebrate, or an Articulate any thing but an Articu-
late, or a Mollusk any thing but a Mollusk, or a Radiate
any thing but a Radiate." Geologically, also, we see no
transition between types. " In the earliest fossiliferous
strata there were the three classes of Radiates, two of
the classes of Articulates, and one of the classes of Ver-
tebrates." The Geographical Distribution of animals
proves the same thing. Thus Agassiz proves that the

PARENTAGE. 43

Series of Rank, of Growth, of Time, and of Geograph-
ical Distribution all show that there is no such gradation
as transmutation implies, and that the connection be-
tween different kinds of living things is not a material
connection, but only an intellectual one, indicating the
plan of the Great Architect.*

5. In all forms of life which have yet come under
human observation, the origin has not been by transmu-
tation, but by parental derivation. Animals and vege-
tables all come from parents of similar organization. If
ever transmutation was the law of origin, it has been
changed, and the law of parentage is now supreme. But
a change of law is inconsistent with the theory of evolu-
tion. Unless the law had been changed, species would
still originate by transmutation, if ever they had such
origin. Such transmutation has never been observed.
The Egyptian monuments prove that the animals of
earliest history remain unchanged, and Agassiz has
shown from the coral reefs in Florida that the animals
of the Gulf of Mexico remain the same as when these
deposits began. Even the varieties which man secures
by " artificial selection " revert to the original type when
the modifying circumstances are removed. Transmuta-
tion has not a single fact to prove it. At best it is but
a theory, and one which all the facts known render most
improbable.

6. The geological evidence shows the entire absence
of intermediate varieties between species, which inter-
mediate forms Mr. Darwin himself admits to be neces-
sary to establish his theory of natural selection. He

* Agassiz, " Methods of Study in Natural History "

44 THE SCIENCE OF LIFE.

claims that the geologic record is defective, and that
when it is better known it will exhibit these forms. But
among more than 30,000 species, many of them repre-
sented by thousands of individuals, some of the interme-
diate forms would occur, if any ever existed. Professor
Pfaff has shown the improbability of the terminal links
only of the chain being preserved by applying the calcu-
lus of probabilities. If 100 individuals of each species
have been found, and 10 intermediate varieties existed,
(a smaller number than Darwin claims,) the probability
against the exclusive appearance of distinct species is as
1:10™!, (i:i with 100 ciphers annexed.*) Professor
Marsh claims to have discovered apparently intermedi-
ate forms between the Palaeotherium and the horse, but
the proof that the Palaeotherium, or the bones referred
to, belonged to the progenitors of the horse has not
been shown, any more than the juxtaposition of bones
of the horse, the zebra, and the ass, would prove them
to be derived from each other. If it were proven, al-
though it would show great variability in that species, it
would not establish transmutation.

7. Geology shows that some of the first forms of life
are also the latest, as the corals. If transmutation be
true, in the struggle for existence they should have
disappeared by being changed into something higher.
That they have not makes against Evolution.

8. Believers in transmutation claim that all living came
into existence by the gradual modification of a primitive
germ, and they find plausibility for this in the develop-
ment of a single bioplast into the various tissues of an

* Johnson's " Cyclopedia, Art. Darwinism."

PARENTAGE. 45

animal. Another analogy is found in the development
of the embryo. As the tadpole is first a fish, and then
a tailed amphibian with lungs and gills, before it be-
comes a frog, so they deem that the history of the
embryo recapitulates the transformations of the species.
This sort of theorizing has given rise to numerous efforts
to arrange the family tree of each species — a branch of
biological speculation termed Phytogeny — and examples
of it may be found in Darwin, Haeckel, etc. Mr. Hux-
ley, although a believer in Evolution, declares that such
summaries of descent are little better than guess-work.*
9. Many instances of complicate and perfect structure
occur both in the vegetable and animal kingdoms which
have no similar structure preceding nor following them.
No scheme of evolution, nor survival of the fittest, can
account for them. The mechanism of the leaf of Venus's
fly-trap, and of Nepenthes, the nettling threads of Hy-
droid polyps, and the peculiar disk-like hairs on the
thigh of the male water-beetle, (Dytiscus marginalis,) are
a few out of almost numberless instances of this fact.
The most perfect dental apparatus in the animal king-
dom, the teeth of Echinus, called Aristotle's lantern, is
also the first to appear, if we trace animal life from its
simplest forms, and there is nothing like it elsewhere.
Like Melchizedek among priests, it has no predecessor
and no successor. Its form and arrangement are a pro-
test against the theories of material development. In
the Rotifer, again, the typical form and structure of the
teeth are entirely different, being an anvil and two ham-
mers. In the Gasteropods they are spiny tongues.

* "Anatomy of Invertebrated Animals."

46 THE SCIENCE OF LIFE.

10. Evolutionists find it difficult, if not impossible, to
account for the first origin of living matter. The bold-
est and most logical among them maintain that it began
spontaneously out of non-living matter. Some, like Sir
W. Thompson, suppose that the germs of living things
were transported to our globe from some other. Others,
as Darwin, hold to the creation of a single germ, or a
few germs, from which all have developed. The doc-
trine of the spiritual origin of living things is beset with
no such difficulties as the mechanical theory. While it
admits a unity of plan resulting from the superintending
intelligence of an all-wise Creator, it sees in living things
a true diversity also. It is hard to imagine how a nat-
uralist can think of " differentiation " without acknowl*
edging a cause of variety ab extra, (from without.)

11. The evidence adduced in favor of spontaneous
generation is always of one kind. A quantity of animal
or vegetable infusion is boiled in a flask, which is then
hermetically sealed. After a time minute forms of life
are found on a microscopic examination of the fluid. It
is taken for granted that all living germs are destroyed
by boiling water, and that therefore the organisms seen
after a few days are developed spontaneously. But
Messrs. Dollinger and Drysdale have shown that some
germs remain alive after exposure to a temperature of
300° F., and Pasteur has found that stopping the necks
of the flasks with cotton wool, so as to filter the air
from all germs, prevents the appearance of Infusoria, as
well as of decay, in fluids well adapted to such organ-
isms. Professor Tyndall has also experimented with a
great variety of fluids in air so deprived of floating germs

PARENTAGE. 47

as to be optically pure, and has had similar results. So
that we may consider the question to be scientifically
settled, and that all living beings come from similar
parentage, or, as Virchow expresses it, " omnis cellula
e cellula" (every cell is from a cell.)

12. Parentage is of two kinds, sexual and non-sexual.
In the first, we sometimes find the sexes distinct, as in
the higher animals, and sometimes united in the same
Individual, as in the stamens and pistils of most flowers,
and as in some animal forms.

Non-sexual generation is seen mostly in the simpler
forms of animal and vegetable life, and as it throws light
on many of the phenomena of nature which would other-
wise be obscure, we notice this form of reproduction here
in a general way, reserving special instances until we
treat of the life-history of each class.

13. In referring to the Vorticella, or bell-shaped ani-
malcule, in our first chapter, mention was made of its in-
crease by self-division. The mass of bioplasm of which
it is composed separates into two masses, which become
separate individuals. This mode of increase is called
Fission, and is quite common among the minuter forms
of life. In Sarcina ventriculi, a sort of vegetable para-
site, the division is into fours, or four times four.

14. A variety of fission, called Gemmation, or Bud-
ding, is often met with. A portion projects from the
mass, and separates to begin an individual existence.
Thus in the fresh-water polyp, or Hydra, a bud gives
rise to an organism like the parent, which becomes de-
tached and independent. Sometimes the product of
buds remains attached, as in plants, and in the Foram-

48 THE SCIENCE OF LIFE.

inifera. In other cases the budding is internal, and
the progeny may or may not remain attached to the
parent.

15. Alternation of generations is a term given to ex-
press a mode of reproduction in which " the parent finds
no resemblance in his progeny until he comes down to
his great-grandson." The Jelly-fish, or Medusae, from
the huge masses cast up by the waves of the sea-shore,
to the tiny bell no bigger than a pea, are developed in
this manner. A ciliated germ, like some of the Infusoria
in form, swims about awhile, then becomes attached,
elongates, and develops into a polyp like the Hydra.
The polyp becomes wrinkled and subdivides until it

looks like a pile
of saucers with
scalloped edges.
This breaks in-
to segments,
each of which
becomes a jel-
ly-fish, which
enlarges and
produces fresh
germs. Fig. 5,

FIG. 5. — Diagram illustrative of the Development of Hydrozoa. .

(The specimen is one of the Lucernaridae.)

i. Ciliated embryo or "planula." 2. Hydra tuba, showing production dlf-
a single individual. 3. Hydra tuba undergoing segmentation.

4. The segmentation becoming more complete. 5. More ad- iCl'S ITOm ITietcl-
vanced stage, in which the tentacles are developed from the first •, . i

or basal segment. 6. Segmentation complete, giving rise to a HlOrpnOSlS, SUCn
free swimming Medusoid. as a butterfly

undergoes in passing from the egg to the perfect insect,
or as most animals pass through in the embryonic state.

PARENTAGE. 49

The caterpillar becomes a butterfly, but the hydra-like
individual referred to produces a number of Medusae.

1 6. Partheno-genesi$\ or virgin production, denotes the
production of new individuals by virgin females without
the intervention of a male.

The Aphides, or plant lice, so often found parasitic
on plants at the close of autumn, consist of winged males
and wingless females. The ova, or eggs, are dormant
through the winter, and the young hatched in the spring
are sexless, but produce viviparously a brood like them-
selves, and this generation produces another, and so on
for ten or twelve generations, the last brood being male
and female as at first. Many other tribes of insects af-
ford examples of partheno-genesis.

17. The subject of this chapter brings us to some of
the deepest mysteries of creation. The parentage of all
living, and the various modes in which the principle of
parentage is manifested — such topics are wonderful seed-
thoughts. It is not likely that we shall ever understand
fully the repetition of individuality, but we see enough
to indicate some of the plans of the Designer of all.
" Lo ! these are parts of his ways . . . but the thunder
of his power who can understand?"

Some analogies between the teachings of biology as
to the genesis of living things, and some of the state-
ments of Scripture, may be readily traced. Mr. Joseph
Cook has been sharply criticised for comparing the birth
of Jesus, as revealed in the Gospels, with partheno-gen-
esis ; yet he had reason for so doing, nor is he alone in his
opinion. In President Dawson's " Origin of the World"
we read, " It is curious that the Bible suggests three

50 THE SCIENCE OF LIFE.

methods in which new organisms may be, and, according
to it, have been, introduced by the Creator. The first is
that of immediate and direct creation, as when God cre-
ated the great Tanninim, (whales.) The second is that
of mediate creation, through the materials previously
existing, as when he said, ' Let the land bring forth
plants,' or ' Let the waters bring forth animals.' The
third is that of production from a previous organism by
power other than that of ordinary reproduction, as in
the origination of Eve from Adam, and the miraculous
conception of Jesus." — P. 229.

t4 The Bible indicates some ways in which living creat-
ures may be modified, or changed into new species, or
may give rise to new forms of life. The human body is,
we are told, capable of transformation into a new or spir-
itual body, different in many important respects, and the
future general prevalence of this change is an article of
religious faith. The Bible represents the woman as pro-
duced from the man by a species of fission, not known
to us as a natural possibility, except in some of the lower
forms of life. The birth of the Saviour is represented as
having been by partheno-genesis, and if it had pleased
God that Jesus was to remain on earth as the progenitor
of a new and higher type of man to replace that now ex-
isting, this might be regarded as the introduction of a
new species." — P. 378.

It certainly disarms skepticism and strengthens the
probability of Bible history, to find such analogies be-
tween the natural world and the record of revelation.

Living beings are not fortuitous nor necessary group-
ings of atoms, either mechanical, as Monism teaches, 01

PARENTAGE. 5 l

monads of force, as Leibnitz wrote, but sparks of spir-
itual existence, given off voluntarily from the Eternal
Parent, having various powers and capacities, yet each
capable of pressing the fleeting atoms of matter into its
service during the period alloted to it in the world. Of
all living beings man is nearest like the Great Father,
in whose image we were created, and who, when heart
and flesh— body and animal life — shall fail, may be the
strength of our hearts and our portion forever.
" For we also are his offspring."

52 THE SCIENCE OF LIFE.

CHAPTER IV.
TISSUE FORMATION.

In regard to the physical universe, it might be better tc substitute for
the phrase " government by laws," " government according to laws," mean-
ing thereby the direct exertion of the Divine Will, or operation of the First
Cause in the Forces of Nature, according to certain uniformities which
are simply unchangeable, because, having been originally the expression of
Infinite Wisdom, any change would be for the worse.— DR. W. B. CAR-
PENTER.

1. A TISSUE is a structure which presents a special
form and serves a special purpose. Thus we find in
plants cellular and woody tissues, and in animals muscu-
lar, nervous, connective, and epithelial tissues, etc.
From tissues are formed organs, as the circulatory, res-
piratory, or digestive organs. A collection of organs
serving a common purpose is called a system, as the nu-
tritive, generative, or nervous systems. The union of
systems in a co-ordinate organism, or the equivalent of
such a union, forms an individual. An individual among
the higher forms of life is a very complex arrangement
of systems and organs ; but in the lower forms more
simple arrangements prevail, which may be considered
equivalent, or representative, of complicated organs, as
in the Rhizopods, referred to in Chap. II., Sec. 5.

2. In the formation of tissues, the peculiar living prop-
erties of bioplasm already described ; the physical agen-
cies of light, heat, electricity, and moisture ; chemical
reactions such as are common to inanimate substances ;

TISSUE FORMATION. 53

and certain properties called osmose and molecular coales-
cence, all combine, so as to render the study of some
tissues quite complex. In other cases the mode of for-
mation is readily traced.

3. The action of physical stimuli, as heat, etc., upon
bioplasm itself is yet very imperfectly known. Light is
not essential to its development, as is seen in the growth
of fungi, the cells of the interior of organisms, and of the
embryo in the dark. Many experiments on bioplasm
have shown that a moderate increase of temperature
quickens its movements, and a corresponding depression
retards them. Electrical, mechanical, and chemical stim-
ulation have similar effects to heat. Yet the action of
these stimuli vary in different cases. The motions of
amoebae are arrested by iced water, and recommence on
raising the temperature, yet the segmentation of trouts'
eggs proceeds well in iced water, but in a warm room they
soon die.* If the change of intensity in the stimulation
be made gradually, and not suddenly, the living matter
will sometimes adapt itself to it without serious disturb-
ance. Animals have been frozen and revived, and there
are instances on record of men enduring for a consider-
able time without much inconvenience the heat of ovens
raised to 500° F.

The influence of light, heat, and electricity upon formed
material of different kinds is very great, but the com-
plexity of the organism and of the phenomena render it
difficult to know what part is supplied by the bioplasm
and what by its product. The vegetable bioplasm of
the interior grows and reproduces its kind, but the

* Strieker's " Manual of Histology."

54 THE SCIENCE OF LIFE.

green chlorophyll which it forms beneath the epidermis,
especially in the leaves, under the influence of light alone
breaks up carbonic acid for the supply of carbonaceous
food. The influence of the more luminous rays, as the
yellow and orange, is greater in this respect than the
others. Gardeners blanch certain plants by raising them
in the dark, yet in the first part of the germination of
seeds Light is injurious rather than beneficial. The in-
fluence of Light upon the direction of the growing parts
of plants, the opening and closing of flowers, etc., may
be chiefly owing to its influence upon the chlorophyll
referred to above, or it may be in some degree a direct
mechanical stimulus. The same amount of Light, how-
ever, is not required for all plants. Some require a very
different amount than others. Among animals Light has
considerable influence upon colors, and still more upon
the process of development. Persons who live in cellars
or in dark streets are apt to produce deformed children,
while recoveries from disease are promoted by the access
delight.

To every species of plant and animal there is a conge-
nial and favorable temperature, although great varieties
exist in this respect, as well as in the power of adapta-
tion to extreme conditions. Many plants, for example,
perish with the slightest frost, yet the little fungus
(Torula) which is the principal agent in yeast, does not
lose its vitality at 76° below zero, although requiring a
somewhat elevated temperature for its active growth.

Electricity possesses the power of exciting the con-
tractility of tjie muscular fibers and the nervous force
in animals in a remarkable degree. It has, however.

TISSUE FORMATION. 55

mechanical, chemical, and thermal influence, in addition
to its own special power, so as to be a very valuable
agent in scientific medicine ; yet the nature of its rela-
tion to the living organism is not yet understood.

In every organized being there is an incessant play
of most varied actions. Buffon well said, " The animal
combines all the forces of nature ; his individuality
is a center to which every thing is referred, a point
reflecting the whole universe, a world in miniature." It
is a one-sided philosophy, however, which
sees in the living thing nothing more than
the forces which are outside of it and play
upon it, and are, to a great degree, subject
to it.

4. Osmose, or osmotic action, is a property
of animal and vegetable membrane, and of
some other porous or soft materials, by which
liquid substances may be separated from
each other. If two liquids (or gases) capable
of mixing with each other are separated by
paper, caoutchouc, or a bladder, one liquid
being suspended in a bladder, or in a cylinder

..i ., , . . , FIG. 6.— Blad-

with its lower end tied over with bladder, der containing
etc., and immersed in the other liquid, the ^ruap' tua^ac^
liquid within will pass through the bladder p^ged in a ves-

. ^ sel of water. The

into the other, (exosmose^) or the liquid with- inward motion of

•11 • 11111 / T \ l^e water (endos-

out will pass into the bladder, (endosmose^ or mose) exceeds the
both endosmose and exosmose will take ^Tof the Tyr-"
place at the same time until there is an equal up' (exosmose')

» and presses the

proportion of liquids on either side. (Fig. 6.) fluid UP the tube-
These phenomena are owing to the physical attraction

56- THE SCIENCE OF LIFE.

the two liquids have for each other and for the mem-
brane separating them.

Crystallizable bodies, as salt, niter, etc., when in solu-
tion, and substances allied to them, as hydrochloric acid,
and alcohol, pass readily through membrane ; but bodies
which do not crystallize, but assume the gelatinous form,
as gum, starch, albumen, hydrate of alumina, etc., pass
through, if at all, with great slowness. Such bodies are
called colloid, or glue-like. Osmose occurs through all
jelly-like bodies, as bioplasm, as well as through fully
formed membrane, and in this manner various liquids
are absorbed or imbibed by the tissues.

5. Molecular coalescence is a term applied to the modi-
fication of ordinary forms of inorganic particles which
occurs when they combine in the presence of organic
matter. Thus it has been found that the crystallization
of certain salts of lime, as the carbonate, when occurring
in a solution of some organic colloid, as gum-arabic, al-
bumen of eggs, blood-serum, and gelatine, is so modified
by such a solution as to resemble many of the calcareous
deposits found in nature.

The bottom of the middle and northern parts of the
Atlantic Ocean is found by the deep-sea dredge, even
at the depth of nearly three miles, to be covered with a
sort of slimy ooze, which Prof. Huxley formerly deemed
to be of animal nature, and termed Bathybius. More
recent investigations have led him to change this opin-
ion. It is regarded as a gelatinous inorganic secretion,
or a product of Diatoms, a family of minute Algae. In
this slime great numbers of globular, shell-like micro-
scopic masses are found, similar to those in the chalk

TISSUE FORMATION. 57

strata of the earth's crust. By experiments in molec-
ular coalescence similar forms have been produced arti-
ficially.

Spicules, like those in the skin of certain marine ani-
mals, have also been formed by molecular coalescence,
as well as laminated plates like cuttle-fish bone. It is
quite probable that many calcareous deposits in tissues,
as in the shell of the bird's egg, in the scales of fishes,
as well as in bone and teeth, may be thus accounted for.
The presence and contact of living colloid matter modi-
fies the ordinary laws of crystallization, and produces
forms differing according to the endowment of the bio-
plasm.

6. In vegetables most of the organs are composed of
cellular tissue, or a congeries of cells. The surface of the
cell, which originates by fission from bioplasm, is
changed into membrane^ or

cell-wall, while a nucleus, (one
or more,) now generally re-
garded as a concentration of
vital power, appears inside.
Within the nucleus, another
spot, the nucleolus, is some-
times seen. (Fig. 7.) The
cell itself presents the ap-

FIG. 7. — Vegetable cell, with nucleus

pearance of a bladder full of and nucieoius.

fluid or semi-fluid material, in the midst of which the

nucleus is visible.

7. Many simple vegetable forms consist of a single
cell, the membranous wall of which is a species of formed
material called cellulose, a substance analogous to starch.

5 8 THE SCIENCE OF LIFE.

Within this membrane the bioplasm is, as it were, im-
prisoned, yet receiving pabulum by endosmose, or
through pores left in the membrane, its vital functions
remain. In the higher plants, as the palm or the oak,
the structure is but an aggregation of cells, some of
which have been modified in form to serve special uses.

8. Near the vegetable cell-wall the bioplasm appears
less fluid than in the middle of the cell, and certain chem-
ical agents cause a partial separation from the membrane,
so as to present, under the microscope, the appearance of
a secondary and gelatinous membrane — the primordial
utricle.

In some vegetable cells the molecular movement of
the contained bioplasm is quite evident, and has re-
ceived the name of Cyclosis. It may be seen under the

FIG. 8. — Three cells from the hair of a potato, showing Cyclosis. Bioplasmic threads
proceed from the nuclei, along which the current flows, in the direction of the arrows.

microscope in the stinging hair of the nettle, and in
hairs from the calyx of Tradescantia Virginica, etc.
(Fig. 8.)

9. Within the cell-wall the bioplasm may be trans-
formed into chlorophyll, or green coloring matter, into
starch, gum, oil, resin, sugar, or other kind of formed
material or mineral substances may crystallize in the
cells, forming what are known as raphides. The variety

TISSUE FORMATION.

59

of vegetable products of this kind is very great. (Figs.
9 and 10.)

FIG. 9.— Cellular tissue of Cc-
reus variabilis, containing : a. a.
Jelly, b. Crystals, c. Starch-
granules.

e /

FIG. 10. — a. b. Cells of a potato, containing
starch, c. Starch-grains apart, d. e.f. Wheat-
starch in different positions.

10. There is often a deposit of silica on the cell-wall,
as in grasses, horsetails, and diatoms. Some of these
latter are beautifully marked with lines and dots, rival-
ing the most complicate patterns of engine-turned en-
graving.

11. Cell-membrane, as all other kinds of formed mate-
rial, grows by addition inside, so that the inner layer is
the youngest. The formed material may get so thick
that nutrition ceases and the bioplasm is wholly trans-
formed, or dies. The solid deposit which fills up the
cells of woody fiber is known as sclerogen, or woody
tissue. (Fig. u.) In Coniferous plants the fibers are

FIG. n. — \Voody fiber.

6o

THE SCIENCE OF LIFE.

marked with depressions, or concave spaces, (glands?)
the centers of which are penetrated, as if some sort of
special communication existed between the bioplasm

FIG. 12. — Glandular fiber, a. External appenr.-uire. b. The sides of two tubes, or fibers,
in contact, c. d. Lenticular cavity between the lubes.

of contiguous cells. (Fig. 12.) Sometimes sclerogen is
deposited within the cell-wall in such a manner as to

produce dots, or pores, or rings,
or spiral fibers, which give
names to the several kinds of

FIG. 13.— Annular and dotted cells. Cells. (Fig. 13.)

12. Vegetable cells are of various shapes, according to
the purposes they subserve. They may be conical, oval,
prismatic, cylindrical, sinuous, branched, entangled, or
stellate. (Fig. 14.) Tubes, or vessels, are formed of
elongated cells. Sometimes such cells join end to end,
and the partition being removed by absorption, a long
tube is formed. Such vessels may be dotted, reticu-
lated, annular, or spiral, from the deposit of woody
tissue, or sclerogen. (Fig. 15.) In the stem of Endog-
enous plants, as palms, etc., bundles of fibre-vascular

TISSUE FORMATION.

61

FIG. 14. — Various forms of cells : a. Conical, b. Oval. c. Prismatic, d. Cylindric.
•-_„• Sinuous, f. Branched, g. Entangled, h. Stellate, z. Fibro-cellular tissue.

FlG. 15.— Annular, dotted, and spiral vessels and ducts.

tissue occur among a mass of cellular tissue; but in
Exogens, as the maple, oak, etc., we' find a more reg-
ular arrangement of pith, medullary sheath, wood, bark,
6

62

THE SCIENCE OF LIFE.

FIG. 16.— a. Transverse stem of Endogen, (Palm.) b. Of Exogen, (Buckthorn.) c. Trans-
verse and longitudinal section of Maple in the beginning of the second year

and medullary rays. (Fig. 16.) The pith is the cellular
tissue of the center ; the medullary sheath a ring of
spiral vessels round the pith, which sends projections
through it to form the medullary rays ; the wood con-
sists of concentric layers of woody and vascular tis-
sue ; and the bark is trade of cellular materials, some-
times containing branching vessels (laticiferous tissue)
conveying milky juice.

TISSUE FORMATION.

13. Leaf -tissue is made up of cells, with cavities,
fibre-vascular bundles, and epidermis. (Fig. 17.) The

FIG. 17. — Perpendicular section of Melon-leaf: h. hairs; st. stomata ; fv. fibro-vas-
cular tissue of the veins.

latter is a sort of skin composed of compressed cells,
among which are found openings, or pores, (stomata^]

each guarded by two or
more elastic cells which
regulate evaporation and
respiration by their ex-
pansion. (Fig. 1 8.)

From the surface of
the epidermis arise hairs,
formed of minute expan-
sions of cellular tissue.
They are of various forms.

FIG. 18.— Epidermis of Madder, with stomata. Some of them SCCretC

volatile oil, others, as the nettle, an acrid fluid. They

64 THE SCIENCE OF LIFE.

often form microscopic objects of great beauty. (Fig.

FIG. 19. — Various forms of vegetable hairs.

The poet Goethe first clearly showed that the various
parts of the plant, from the seed to the blossom, are but
modifications of the leaf. All the parts of a flower,
calyx, corolla, stamens, and pistil, are only leaves adapt-
ed for 'peculiar functions. They were not originally
leaves, and afterward transformed, but they are formed
of the same elements, and arranged upon the same plan,
and in the changes which they undergo and the relation
they bear to each other, they follow the same laws as
leaves do.

. All leaves are arranged upon the stem after two
leading patterns — the whorl and the spiral ; but as by
teasing out the whorl we get the spiral, and by com-
pressing the spiral we get the whorl, we may regard
them as essentially the same.

14. In the animal kingdom, with the exception of

TISSUE FORMATION. 65

those simple forms of life already described, which in-
crease by fission or budding, (Chap. III., Sec. 12, 13,) the
germ of all the tissues is first a piece of simple bioplasm
derived from the vesicles of the ovary. This is fertilized
by fusion with similar bioplasm derived from the male.
It then acquires a membrane, and exhibits a nucleus
and nucleolus, as in the case of the primitive vegetable
cell. Changes, however, take place in the animal ovum
which we do not observe in the vegetable, and these
changes differ also in the different classes of animals.
In the higher classes the ovum separates into two
spheres, which sub-divide into four, then into a mul-
berry-like mass of cells, or morula. (Fig. 20.) These cells

FIG. 20. — Segmentation of Mammalian Egg. A. Division into halves. B. Further
subdivision. C. Mulberry mass, or Morula.

in the vertebrates arrange themselves into a layer lining
the vitelline membrane, on one side of which is a sort of
pouch, or blastoderm, consisting of three layers of cells,
the epiblast, the mesoblast, and the hypoblast. The
first of these produces the skin, the middle one the
nervous, muscular, and vascular systems, and the latter
the lining of the intestinal and respiratory organs.

The alimentary canal is at first a straight tube closed

at both ends. As it grows faster than the body it is
6*

66 THE SCIENCE OF LIFE.

thrown into a spiral coil, and at several points it dilates,
to form the stomach, etc. The mouth is developed
from an infolding of 'skin. The liver is an outgrowth
from the digestive tube, at first a cluster of cells, then oi
follicles, and finally a true gland. The lungs first ap-
pear as minute buds from the upper part of the aliment-
ary canal, or pharynx.

15. The transformation of the cells of the blastoderm
into various animal tissues is effected in various ways.

a. An interstitial deposit of formed material may occur
in the bioplasm, or cell. Thus oil-globules, pigment, or
vacuities may greatly modify the appearance and actions
of the cell. The action of tannin, or boracic acid, etc.,
upon the red blood disks of animals, shows each of them
to be really double, having a continuous interstitial sub-
stance deposited in each disk. Prof. Brucke, who first
investigated this structure, called the parts of the disk
respectively, the zooid and the cecoid, the former being
the part which, in the living state, contains also the
haemoglobulin, or red coloring matter.

b. Cells are sometimes found scattered through an
intercellular material, the product of cells or of cells
transformed and fused together. This intercellular mass
may either remain continuous, or split up into fibers.
In this way fibrous connective tissue, cartilage, etc., may
be formed. (Fig. 21.)

c. The cells which cover surfaces, and through which
all interchange between the body and the external world
is carried on, are called epithelial. They differ in shape,
either from mutual pressure or function, some being
flat and squamous, (or scaly,) and others columnar.

TISSUE FORMATION. 67

Some of the latter have cilia, or hair-like projections,
whose motions produce a current over the surface.

A

FIG. 21. — Connective-tissue. A. White and yellow fibers. B. Developing Cells of
connective tissue.

Thus the skin, or mucous membrane, is not a continu-
ous membrane, but made up of cells, the nuclei of which
exhibit the remains of the bioplasm or living matter
from which they sprang. (Fig. 22.)

FIG. 22. — Epithelial cells, i. Squamous epithelium from the skin, showing the change
from bioplasm to horny scurf. 2. Tessellated Ep. from serous membrane. 3. Columnar
Ep. from intestine. 4. Ciliated Ep. from air-passages.

68

THE SCIENCE OF LIFE.

d. In bone and other hard tissues, as the teeth, the
intercellular substance is solidified by salts of lime de-
posited in a modified form by molecular coalescence.
Sec. 3. In this case the bioplasm, or cell, is limited to
certain spaces, or lacuna, and receives nourishment
through small canals, or canaliculi. (Fig. 23.)

FIG. 23. — Transverse section of a long bone. a. Haversian canal, b. Concentric
laminae, c. Laminae of connection, d. Lacunae, with their system of tubes.

e. Some fibrous structures may be formed by moving
particles of bioplasm, leaving behind them a thread of
formed material. In voluntary muscular fiber this formed
material is duplex, and in certain nerve-ganglia the fiber

TISSUE FORMATION. 69

is spirally coiled around another by the forward and
rotary motion of the bioplasmic cell.

1 6. We may consider the living organism, either ani-
mal or vegetable, as a building, a workshop, or a labora-
tory, and in each view the cell, or bioplasm, plays the
most important part.

If we regard an organism as a building, the cells are
the constituent parts, or building-stones. The most
simple forms of life, as we have said, are single cells,
while the more complex are composed of myriads of
these cells, with the materials produced by them, ar-
ranged in various forms, according to the nature of the
individual. Thus in the yeast-plant (Torula) the cells
touch each other at only one or two points, while the
wood-cells of higher plants adhere in their entire extent
by means of formed material. Vessels, or ducts, are
either elongated hollow cells, or are formed by the
union of cells. In every structure, except the most
primitive, we also find secret chambers and grottoes
which we should not previously have suspected ; and
where strength is needed, provision is made for it by the
deposit of hard substance, and by the interlacing of
fibers, once cellular, in a most wonderful manner. Even
the temple of Solomon, in all its glory, was not more
complete in architectural details than the structure of
many of our plants and animals. As that temple was
said to have been erected without the sound of hammer
or saw, so the animated edifice is built silently, story
after story, from day to day, until its life-work is accom-
plished.

Such a structure is a workshop, as well as a building.

^o THE SCIENCE OF LIFE.

There is something in it full of peculiar activity, alto-
gether different from the forces which belong to metals
and stones, or other inorganic bodies. We call it Life,
and the more we observe its powers the more we shall
be convinced that it is the Master, and not the slave, of
matter, and that the forming power is different from the
thing which is formed. It makes its own workshop and
its own tools, and compels the physical forces of inor-
ganic nature to assume new and different relations, so as
to serve its own purposes. It forms its own building-
stones, and elevates them to their places against gravity,
removes such as are in decay and replaces them with
others, and strengthens such parts as are most exposed
to wear or strain.

The organism is also a laboratory. There Life, as a
subtle Alchemist, sits and transmutes the chemical ele-
ments around it into new and useful forms, in a way
which surpasses all our knowledge. Thus from the same
materials, and under the same conditions of light, heat,
and electricity, one cell will make starch, another fat,
another sugar, albumen, flesh, coloring-matter, acids, or
alkalies ; nay, even, in parts of the same cell different
materials may be produced.

17. Every glance into the marvels of organic structure
reveals new wonders. As in the remote regions of
space we may trace myriads of suns, with nebulous films
and world-islands, which hide from us what is behind
them, so here every step reveals something new and
gives glimpses of something beyond. The details of
Histology would fill a large volume, and even an ordi-
nary life-time is insufficient to do more than to gather

TISSUE FORMATION. 71

up a few facts and arrange them in proper relations, yet
the pursuit of knowledge continually brings us nearer to
the fountain of Absolute Truth. To the microscope,
even more than to the telescope, belongs the introduc-
tion of the inquirer into the arcana of the universe. If
it does not lead us outward into realms of space, which
exhibit the same relations of scientific and abstract truth
as the world on which we dwell, it leads us inward to-
ward the foundations of our own existence, and shows,
that the relations of truth are as perfect in the descend-
ing as in the ascending sphere. If we see not life itself,
we see its first beginnings, and the process of its devel-
opment. If we see not Nature in her undress, we trace
the elementary warp and woof of her mystic drapery.
From both telescope and microscope alike we learn
that the widening sphere of knowledge is constantly
encircled by the unknown/ yet through them we see
above and beneath us a myriad instances of the skill and
providence of a Great Designer, who is God and Father
of all. The living atom shines with truth no less than
the star.

" Forever singing as they shine,
The hand that made us is divine."

72 THE SCIENCE OF LIFE.

CHAPTER V.

TYPES OF CONSTRUCTION.

. . . Much less, then, have we any idea of the substance of God. We
know him only by his most wise and excellent contrivances of things and
final causes ; we admire him for his perfections ; but we reverence a ul
adore him on account of his dominion : for we adore him as his servants ;
and a god without dominion, providence, and final causes, is nothing else
but Fate and Nature. Blind metaphysical necessity, which is certainly
the same always and every-where, could produce no variety of things. All
that diversity of natural things which we find suited to different times and
places could arise from nothing but the ideas and will of a Being neces-
sarily existing. — SIR ISAAC NEWTON'S Principia.

1. OUR imperfect knowledge of nature must always
give a provisional character to our classifications. If
they present the knowledge we possess in a useful and
compact form, it is all they can be -expected to do. Fur-
ther knowledge may confirm or overthrow the most per-
fectly symmetrical system. Tennyson has well sung :

" Our little systems have their day,

They have their day and cease to be,
They are but broken lights of thee,

And thou, O Lord, art more than they."
— In Mcmoriam.

Yet an arrangement may be true although imperfect.
We may see plainly the leading outline, while a myriad
details may be unknown.

2. In attempting to arrange organic forms it is impos-
sible to place them in a single line, like the steps of a
ladder, according to structural rank. There are no such

TYPES OF CONSTRUCTION. 73

gradations in nature as some imaginations have conceived.
There are so many relationships, both of structure and
of function, that a single series is out of the question.
There are many series, and series, also, within series.
Organic forms seem to be placed in radiating groups
rather than lines, each group being connected, not with
two groups merely, one above and the other below, but
with several. Living things are, therefore, best studied
in groups, or circles, according to prominent types or
representative forms. These groups will, doubtless, be
unequal and dissimilar, and will be far from representing
the grade of organization ; yet they will be of great use,
not only to the memory, but also in indicating the gen-
eral order of the universe.

3. The unity of organic nature is seen in the similarity
of bioplasm, or living matter ; its variety is shown in the
multiform arrangements of structure in living beings.
That all this variety can be intelligently connected to-
gether in a few comprehensive groups, exhibiting plans
of structure, is proof positive of the intelligence of the
creative power. Agassiz has well said, " If these classi-
fications are not mere inventions, if they are not an at-
tempt, to classify for our own convenience the objects we
study, then they are thoughts which, whether we detect
them or not, are expressed in Nature — then Nature is
the work of thought, the production of intelligence, car-
ried out according to plan, therefore premeditated — and
in our study of natural objects we are approaching the
thoughts of a Creator, reading his conceptions, interpret-
ing a system that is his and not ours."

4. Types are comprehensrve natural groups of living

74 THE SCIENCE OF LIFE.

forms, founded on plans of structure or structural ideas.
Classes comprise all forms which agree simply in a special
modification of the type to which they belong. The
type represents the plan, but there may be several ways
of executing the plan, and these ways illustrate the
classes. In human works of art " there are certain ar-
chitectonic types, including edifices of different materials,
with an infinite variety of architectural details and ex-
ternal ornaments ; but the flat roof and the colonnade
are typical of all Grecian temples, whether built of mar-
ble or granite or wood, whether Doric or Ionic or Corin-
thian, whether simple and massive or light and orna-
mental ; and, in like manner, the steep roof and pointed
arch are the typical characters of all Gothic cathedrals,
whatever be the material or the details. The architect-
ural conception remains the same in all its essential ele-
ments, however the more superficial features vary. Such
relations as these edifices bear to the architectural idea
that includes them all, do classes bear to the primary di-
visions," or types.* Thus Fishes, Amphibians, Reptiles,
Birds, and Mammals are classes under the Vertebrate
type of animal life.

An Order is a group of families, or genera, related
to one another by a common structure. Thus Cats,
Dogs, Hyenas, and Bears are linked together, since their
teeth, stomachs, and claws show the carnivorous habits
of the order Carnivora.

A Family, or Tribe, does not allude to the progeny of
a known stock, but refers to a group of genera having
similarity of form. The term was first introduced into

* Agassiz, " Methods of Study."

TYPES OF CONSTRUCTION. 75

Botany in France, in connection with what is called the
natural system of classification. To prevent confusion,
the similarity of form determining families should be
based on structure and not mere resemblance.

A Genus is a group of species having the same essen-
tial structure. Thus the allied species, Cat, Tiger, and
Lion, belong to one genus.

A Species is the smallest group of individuals which
can be defined by several constant characteristics. They
are so alike that it is possible for them to have descended
from one pair. A cross between two species, as the
Horse and Ass, is called a hybrid ; as the Mule.

Individuals are the units of organic life. A complete
animate existence is an individual, whether separate, as
man, or living in a community, as the Coral. When two
or more individuals differ by a single peculiarity, such
as color, or outline, or size, one is called a variety of the
other, as the races of Men and breeds of Cattle. A cross
between distinct races is called mongrel.

Vegetables and animals are separated from each other
under the term kingdom, and the types of structure in
each kingdom are called sub-kingdoms. Thus in-the ani-
mal kingdom we have the sub-kingdoms of Vertebrates,
Radiates, etc.

There are no such things as genus, species, order, class
etc. They are but abstract terms, expressing relation to
a plan, or the harmony of intelligent design which pre-
sides over all things.

5. A real type, or plan, includes all those individuals,
species, etc., which are similar in character. But it is
not always easy to determine similarity of character.

76 THE SCIENCE OF LIFE.

From the earliest times of history down to Cuvier,
naturalists were in the habit of regarding similarity of
external form and evident purpose as indicating anal-
ogies, and so far as functional design is concerned, the
principle may be considered right. But purpose and
plan for a purpose are different, and modern science
seeks for its types in the characters of internal structure
and development.

6. Parts, or organs, having similar origin and develop-
ment, and therefore the same essential structure, are
called homologous ; while those which are anatomically
different, though corresponding in use, are called analo-
gous. Thus in the vegetable kingdom the tendril of the
Vine, which is a transformation of the flower-stalk ; that
of the Pea, which is a prolongation of the leaf-stalk ; that
of Gloriosa, which is the point of the leaf itself; and that
of StrophantkuS) which is the point of the petal ; are all
analogous, but not homologous. The arms of Man, the
fore-legs of a Horse, the paddles of a Whale, the wings
of a Bird, the front flippers of a Turtle, and the pectoral
fins of a Fish, are homologous but not analogous. The
wings of the Bird, Flying Squirrel, and Bat are not ho-
mologous, since that of the first is developed from the
fore-limb only, that of the Squirrel is an extension of the
skin between the fore and hind limbs, and that of the
Bat is a membrane between the fingers and down the
side to the tail. The air-bladder of a Fish is homologous
with a lung, but analogous to the air-chamber of the
Nautilus. In the functional analogies, perhaps more
evidently than in the structural homologies, we trace
evidence of purpose, or design. " Blind metaphysical

TYPES OF CONSTRUCTION. 77

necessity," as Newton called Fate and Nature without
God, could certainly produce no such " variety of things "
as we see here, while the unity pervading the functional
character of the different organs is plain enough proof
of their being the work of the same Artisan.

Various functions are attained by a modification of
similar structure. Thus the simplest plant differs from
the most complex principally in this — that the whole
external surface of the former participates equally in all
the operations which connect it with the external world,
as those of Absorption, Exhalation, and Respiration,
while in the latter these functions are confined to certain
parts of the surface. So in the highest animals, the or-
gans adapted to the functions of Absorption, Exhala-
tion, Respiration, Secretion, and Reproduction, are all
composed essentially of a membrane which is a prolonga-
tion of the general surface, while this general surface is
the sole instrument for the performance of these func-
tions in the lowest animals, and shows no special adap-
tation for one or another of them. So that it may be
expressed as a general truth of Biology, that " through-
out all animate Creation, the functional character of the
organs which all possess in common, remains the same ;
while the mode in which that character is manifested
varies with the general plan upon which the being is
constructed."*

In all living things the attainment of function is the
cause of modification of structure. This gives evidence
of Creative plan, or design, in direct opposition to the
theory of gradual evolution of structure, and is proof also

* Carpenter's "General and Comparative Physiology."

7*

78 THE SCIENCE OF LIFE.

of the essential differences between living beings, since
the plan of structure varies for attaining similar purpose.
7. Cuvier proposed four primary divisions of the ani-
mal kingdom, because, he said, they are constructed on
four different plans. These plans may be briefly stated
as follows : " In the Vertebrates there is a vertebral col-
umn terminating in a prominent head ; this column has
an arch above and an arch below, forming a double in-
ternal cavity. The parts are symmetrically arranged on
either side of the longitudinal axis of the body. In the
MolluskS) also, the parts are arranged according to a bi-
lateral symmetry on either side of the body, but the
body has but one cavity, and is a soft, concentrated
mass, without a distinct individualization of parts. In
the Articulates there is but one cavity, and the parts are
here again arranged on either side of the longitudinal
axis, but in these animals the whole body is divided
from end to end in transverse rings or joints movable
upon each other. In the Radiates we lose sight of the
bilateral symmetry so prevalent in the other three, ex-
cept as a very subordinate element of structure; the
plan of this lowest type is an organic sphere, in which
all parts bear definite relations to a vertical axis." *
Leuckart proposed to subdivide the Radiates into two
groups ; the Coelenterata, including Polyps and Acalephs,
or Jelly-fishes — and Echinoderms, including Star-fishes,
Sea-Urchins, and Holothurians, but Agassiz shows that
the differences between them are not differences in the
plan, but merely a difference in the execution of the
plan, since both are equally radiate in structure.
* Agassiz, " Methods of Study."

NSTRUCTION.

TYPES OF CONSTRUCTION. 79

By this radial symmetry we are conducted toward the
Vegetable Kingdom. Thus in the higher Fungi the dis-
position of organs is as radiate as in Radiated animals.
In Mosses and Ferns there is a spiral arrangement of
leaves around the axis, which may be considered the
regular law of growth in the higher plants, although
sometimes obscured by special modifications.

8. It is a popular error, fostered by the assertions of
certain Monistic writers, that the higher animals pass
through all the phases of lower life. This false notion is
based upon too strict an interpretation of Von Baer's gen-
eralization in Embryology, that " a heterogeneous or spe-
cial structure arises by gradual change out of one more
homogeneous or general." Every division of the Animal
Kingdom has its characteristic method of developing.
" The Vertebrate arises from the egg differently from the
Articulate ; the Articulate differently from the Mollusk ;
the Mollusk differently from the Radiate." *" Every
grand group early shows that it has a peculiar type of
construction. Every egg is from the first impressed with
the power of developing in one direction only, and never
does it lose its fundamental characters. The germ of the
Bee is divided into segments, showing that it belongs to
the Articulates ; the germ of the Lion has the primitive
stripe — the mark of the coming Vertebrate. The blasto-
dermic layer of the Vertebrate egg rolls up into two
tubes — one to hold the viscera, the other to contain the
nervous cord ; while that of the Invertebrate egg forms
only one such tubular division. The features which 'de-
termine the subkingdom to which an animal belongs

, , _ * Ac-assiz.

8o THE SCIENCE OF LIFE.

are first developed, then the characters revealing its
class." * Dr. Carpenter says : " The human embryo is
never comparable with a Fish, a Reptile, or a Bird, much
less with an Insect or a Mollusk. However close may
be the resemblance between the embryo of Man and the
embryo Fish, there is no real correspondence between
the embryo of Man and the completed Fish. Each germ
has a certain capacity of development peculiar to itself,
since like produces like"

9. To attain a true knowledge of the order of creation,
or of the types of structure among organic forms, it is
necessary not only to consider internal construction and
relationships, and the process of embryonic development,
but also to trace the life-history of each, and especially
the metamorphoses to which they may be subject at
various periods. Among the lower Fungi there is a
kind of polymorphism (polys, many ; morpha, form) fre-
quent, by which several forms may be developed by
spores, or seeds, which have identically the same origin.
Few animals come forth from the egg in perfect condi-
tion. The embryonic Star- fish has a long body, with
six arms on a side, from one end of which the young
Star-fish is budded off. Soon the twelve-armed body
dies, and the young animal is of age. Most Insects un-
dergo complete change of form, a metamorphosis; i.e., ex-
hibit four distinct stages of existence — egg, larva, pupa,
and imago. Among the vertebrates the most common
and most remarkable transformation is that of the Frog.
It is first, after hatching from the egg, a tadpole, with a
tail, but no legs, gills instead of lungs, a heart like that

* Orton's " Comparative Zoology."

TYPES OF CONSTRUCTION. 81

of a fish, a beak for eating vegetable food, and a spiral
intestine to digest it. As it matures, the hind legs show
themselves, then the front pair, the beak falls off, the
tail and gills waste, lungs are formed, the digestive ap-
paratus is changed to suit an animal diet, the heart is
altered to the Reptilian type by the addition of another
auricle — in fact, skin, muscles, nerves, bones, and blood-
vessels vanish, being absorbed atom by atom, and a new
set is substituted.*

10. With the caution referred to in Sec. I we may pre-
sent an outline of the types of living forms.

The most general and comprehensive type is that of
bioplasm, or living matter, described in Chap. II, and
characteristic of both animals and vegetables. The next
most comprehensive type of structure is that of Vegeta-
ble forms in which the bioplasm is invested, or, as it
were, imprisoned, in each of its component cells by a sac
of cellulose, or some analogous compound, (Chap. IV,
Sec. 5,) and whose most characteristic work, or peculiar-
ity, is its power of manufacturing albuminoid matter out
of simpler chemical elements. In Animal forms there
is no such cellulose investment, nor can they make albu-
minoid matter from inorganic elements.

In the Vegetable Kingdom we may arrange organic
forms under the following general divisions, or principal
types:

i.) PROTOPHYTES, or simplest vegetable forms, an-
swering to the Unicellular Alga.

2.) THALLOGENS, which are a mere expansion of cel-
lular tissue, without complete distinction between stem,

* Orton.

82 THE SCIENCE OF LIFE.

root, and leaves. These include Fungi, Alga, and
Lichens.

3.) ACROGENS. Plants which grow in height and not
in diameter. Liverworts, Mosses, and Ferns.

4.) ENDOGENS. Vascular plants, in which the wood
and cellular tissue are mixed throughout, without dis-
tinct annual layers. The seed has but a single lobe, or
cotyledon.

5.) EXOGENS. Vascular plants having distinct annual
layers of woody fibers, and radiations of tissue from the
medulla to the bark. The embryo has two seed-lobes,
or cotyledons.

In the Animal Kingdom we have the following typical
forms, or subkingdoms :

I. PROTOZOA. Simplest animal forms, being com-
posed of bioplasmic jelly. Monera, Gregarinay Rhizo-
pods, Infusoria, and Sponges.

II. RADIATA. Radiate animals, which are subdivided
into— I. CCELENTERATA, with distinct body-cavity, ten-
tacles, and nettling thread-cells. Hydrozoa, Anthozoa^
Ctenophora. 2. ECHINODERMATA, with distinct aliment-
ary canal and nervous ring. Crinoids, Asteroids, Holo-
thurians, Echinoids.

III. MOLLUSCA. Soft unsymmetric animals. Digest-
ive system developed. Nervous system irregular. Poly-
zoans, Tunicates, Brachiopods, Lamellibranckiates, Gaster-
opods, Cephalopods.

IV. ARTICULATA. Nervous ventral cord double.
Limbs on same side as nerve-cords. Annelids, Crusta-
ceans, Arachnoids, Myriapods, Insects.

V. VERTEBRATA. Double nervous system; one on

TYPES OF CONSTRUCTION. 83

upper side of alimentary canal, the other spinal ; limbs
opposite nerves. Fishes, Amphibians, Reptiles, Birds,
Mammals, Man.

II. In the Frontispiece the characteristic features of
biological types are represented. In the outline section
of each of the four types of higher animals the large
shaded spot shows the alimentary canal, the dark spot
the position of the heart, and the open rings the nervous
system. A diagram of the latter also accompanies each
of those types.

84 THE SCIENCE OF LIFE.

CHAPTER VI.

PROTOPHYTES.

Let no presuming impious railer tax
Creative Wisdom, as if aught was formed
In vain, or not for admirable ends.
Shall little haughty ignorance pronounce
His works unwise, of which the smallest part
Exceeds the narrow vision of her mind?

— THOMSON.

1. VEGETABLE structure has been already character-
ized as bioplasm imprisoned, or invested with a cell-wall
of cellulose. In some of the simplest forms, or Proto-
phytes, each cell is separate from the rest, others form
masses of cells in a sort of gelatinous or slimy invest-
ment, while other forms exhibit a definite adhesion be-
tween the cells, so as to prefigure a regular plant-like
structure, although each cell is a repetition of its parent-
cell, and is capable of living apart.

2. The life-history of simplest Protophyte is exem-

plified in the Pal-.
moglcea macrococ-
ca, (Fig. 24;) a sort
of green scum or
slime, growing on
damp stones, etc.
The microscope
shows this to con-

FIG. 24.— Development of Palmoglcea macrococca. sist of a multitude

PROTOPHYTES. 85

of green cells, each surrounded by a gelatinous envel-
ope, and sometimes a nucleus, or more solid aggregation,
which is considered the center of vital activity, is seen
in the cell. The green particles, or granules, which fill
the cells, are formed material called chlorophyll. Through-
out the vegetable kingdom the presence of chlorophyll
is necessary to enable the plant, under the stimulus of
bright sunlight, to break up carbonic acid, evolve the
oxygen, and appropriate carbon as food. In the absence
of sunlight all plants become oxidized, and evolve car-
bonic acid. The cells of the Palmogloea multiply by
binary subdivision, or fission. (Chap. Ill, Sec. 12.) This
multiplication is an act of growth, and differs from simi-
lar self-division in the higher plants by the purpose man-
ifested, and the plan for a purpose, seen in the " differ-
entiation " of cells in the higher orders for the production
of special organs.

In these lowly plants there is a process similar to the
plan of reproduction in the more complex forms. A
pair of cells will sometimes reunite, or fuse together, first
by means of a narrow bridge, and then a larger mass,
and finally a complete fusion. The mass is termed a
Spore, (from the Greek spora, a seed,) and is the primi-
tive cell of a new generation formed by fission.

3. In a form allied to the above, the Protococcus pluvi-
alis, (Fig. 25,) not uncommon in rain-water, a somewhat
greater variety of conditions has been seen. It is found
still, or quiescent, and motile. In the first form the bio-
plasm is surrounded with a wall of cellulose, and filled
with granules of green or red chlorophyll. These still

cells multiply by self-division, each producing two, four,

8

86 THE SCIENCE OF LIFE.

eight, or sixteen new cells. The new cells are motile, hav-
ing each two long vibratile filaments or cilia. They may

be seen swimming,
tumbling, or rotat-
ing in the water.
At times they are
surrounded by a
sac, which may be
at some distance
from the bioplasm.
The motile cells
may also multiply

FIG. 25. — Development of Protococcus : a. Still form.
b. Motile form. c. Self-division and zoospores. by Subdivision, and

in some cases the minute primitive cells, when set free,
have very active movements, and rank as Zoospores, (liv-
ing spores,) or Micro-gonidia, (small angular particles,
from division of the bioplasm.) The varieties connected
with the history of this single plant have been sometimes
described as distinct species, and even genera of Animal-
cules, because of their shape and motions.

4. The family of Palmellacece, to which the forms re-
ferred to belong, contain some kinds of singular interest.
The " Red Snow," which sometimes colors extensive
Alpine or Arctic tracts, is composed of myriads of Pro-
tococcus cells, in a quiescent state, with the chlorophyll
of a red color. The Palmella cruenta, or " Gory Dew,"
appears sometimes as tough gelatinous masses of the
color of coagulated blood, and extends over a consider-
able area. In this way we may account for showers of
flesh, blood, etc., which are often regarded as bad omens
by the ignorant.

PROTOPHYTES. 8?

5. The family Volvocinea has been long considered
of singular beauty and interest to the microscopist.
The Volvox globator (Fig. 26) was described by Leeu-
wenhoek about
one hundred and
fifty years ago,
and from its shape
and rolling mo-
tion was called the
globe animalcule,
but its vegetable
character is now
generally admit-
ted. It is about

One thirtieth of FIG. 26.-Volvox globator.

an inch in diameter, and appears to the unassisted eye
to be a little green speck moving slowly through the
water. On examining with the microscope the Volvox
is seen to be a pellucid sphere studded with minute
green spots, connected together by threads. From each
of these spots proceed two cilia, so that the entire sur-
face of the globe is beset with vibratile filaments, to whose
combined action its rolling motion is due. Within the
globe may be generally seen from six to twenty other
globes, of varying sizes, which are set free by the burst-
ing of the parent globe. Sometimes a third generation
may be seen within the secondary spheres. Careful ob-
servation of the development of the Volvox has shown
that the ciliated cells referred to above, analogous to the
zoospores of Protococcus, sometimes appear like moving
Amoebae. (Chap. II, Sec. 2.) This is not an uncommon

88

THE SCIENCE OF LIFE.

phenomenon among Protophytes, and shows that the
bioplasm of the vegetable and animal cell have similar
properties.

6. Dr. Carpenter recommends those who wish to study
the development of " zoospores," and other phenomena
of Protophytes, to have recourse to the little plant called
Achyla prolifcra, which grows parasitically upon the

bodies of dead flies
in water, etc. The
naked eye perceives it
as tufts of minute col-
orless filaments, which
the microscope shows
to be long tubes con-
taining granular bio-
plasm, which exhib-
its the motion called
Cyclosis. (Chap. IV,
Sec. 6.) After about
thirty-six hours the
bioplasm accumulates
in the dilated ends of
the filaments, and its

FlG. 27. — Development of Achyla prolifera : A. Di-
lated extremity of a filament, 6, separated from the endochrome, Or gran-
rest by a partition, «, and containing young cells in t I'm f f **r
progress of formation. B. Conceptacle discharging Ulai> COJ natter,
itself, and setting free young cells, a, 3, c. C. Portion Breaks UP into dis-
of filament, showing the course of the circulation of
granular protoplasm. tinct ttiaSSCS, each of

which becomes a zoospore, or " motile gonidium,"«with
cilia, and is set free by rupture of the wall of the parent
cell. (Fig. 27.)

7. The family Desmidiacece consists of minute Proto-

PROTOPHYTES.

89

phytes of a grass-green color, growing in fresh water.
The cells are generally independent, but in some species
remain adherent one to another so as to form a filament.

FIG. 28.— Various species of Staurastrum : A. Staurastrum vestitum. B. Stau-
rastrum aculeatum ; C. Staurastrum paradoxum ; D. E. Staurastrum brachiatum.

Some species have spiny projections of the outer coat,
which is of a horny consistence, as in Fig. 28. Others are
notched on the sides ; some, as the Closterium, (Fig. 29.)

FIG. 29. — Economy of Closterium lumilci : A. Frond showing central separation at a,
in which large globules, £, are not seen. B. One extremity enlarged, showing at a the
double row of cilia, at b the internal current, and at c the external current. C. External
jet produced by pressure on the frond. D. Frond in a state of self-division.

8*

THE SCIENCE OF LIFE.

are smooth. In the latter a circulation of fluid may be
seen between the cellulose coat and the " primordial
utricle." (Chap. IV, Sec. 6.) Some consider this circula-
tion to be caused by cilia, but it is rather doubtful. We
are inclined to regard it as an exhibition of the molec-
ular motion of bioplasm already described. Many of
the Desmids multiply by subdivision, but the plan is
modified so as to maintain the symmetry characteris-
tic of the tribe. At other times multiplication takes
place by the subdivision of the endochrome into gran-
ular particles, or " gonidia," set free by rupture of the
cell-wall.

The process of conjugation differs from that of Palmo-
glaea, since each cell has a firm external envelope, which
cannot coalesce with another. In Cosmarium, (Fig. 30,)

for example, the conjugating
cells become deeply cleft
and separate, so that the
contents pour out freely, at
first without a protecting
membrane. At length it
acquires an envelope, and
becomes a sporangium, or
spore-case, of reddish-brown
tint. It is covered with
spines, and greatly resem-
. bles certain fossil forms

ric. 30. — Cosmanum botrytts : A. Ma-
ture frond. B. Empty frond. C. Transverse found in flint called Xan-
view. D. Sporangium, with empty fronds.

thidia. The Clostena con-
jugate after a somewhat similar manner, and it is
not uncommon to find a pair in this condition, but

PROTOPHYTES. 91

their sporangia are smooth instead of tuberculated or
spiny.

8. The families of Algae, called Oscillator iacece, Nosto-
chacece, Confervacece, and Conjugates, may all be consid-
ered as Protophytes, but a brief description only can be
given here. The structure is generally microscopic.

The Oscillatoria are tubular filaments with partial
subdivisions, formed by the elongation of their primor-
dial cells, occurring in fresh and salt water, and on damp
ground. They have very curious movements, sometimes
swaying like a pendulum, and at others bending at the
extremity from one side to another, or moving straight
onward.

Nostocs are beaded filaments lying in masses of green-
ish gelatinous matter. As the jelly forms rapidly in
damp weather, they have been termed " fallen stars."
The alchemists often refer to this substance, and it enters
into many of their recipes for the pretended transmuta-
tion of metals.

The Conferva may be found in almost every pond or
ditch, but are especially abundant in running water.
They constitute the greater part of those green threads
which are found in streams, or near the sea-shore. Each
thread is a long cylinder, in which the endochrome, of a
green, brown, or purplish hue, is either distributed uni-
formly through the cell, or arranged in a net-work, or
spiral form. It increases by binary subdivision in the
terminal cell, as well as by zoospores produced within
the cells.

The family Conjugates is so called because the fila-
ments are so constantly yoked together. They are

92

THE SCIENCE OF LIFE.

generally found in still water. In an early stage of
growth the endochrome is diffused through their cavi-
ties, but after a time arranges itself in regular spirals.
Then adjacent cells put forth protuberances which coa-
lesce, and a passage is formed between the cells. The
endochrome of one cell passes over into the cavity of the
other, forming a sporangium, or spore-case. (Fig. 31.)

FIG. 31. — Various stages of the history of Zygnema quininum : A. Three cells, «, £, r,
of a young filament, of which b is undergoing subdivision : B. Two filaments in the first
stage of conjugation, showing the spiral disposition of their endochromes, and the protu-
berances from the conjugating cells. C. Completion of the act of conjugation, the endo-
chromes of the cells of the filament a having entirely passed over to those of filament £,
in which the sporangia are formed.

9. The most beautiful and interesting unicellular forms,
now generally conceded to be vegetable, are found among
the Diatomacece. Their motions caused many to regard
them as animals, but naturalists now agree in calling
them Protophytes. They are called Diatoms because
of their extreme brittleness and the ease with which
a chain of them may be broken into its component cells.
Like the Desmids, they are simple cells containing endo-

PROTOPHYTES. 93

chrome, with a firm external covering. In the Diatoms,
however, this envelope is consolidated by silex, or flinty
matter, sometimes also by iron. The silicious envelope
of each " frustule," or cell, is covered with most elabo-
rate and beautiful marking, and consists of two valves,
or plates, closely applied to each other, like the valves of
a Mussel, along a suture, or line of contact. If the valve
is hemispherical, the cavity will be globular; if a segment
of a sphere, the cavity will be lenticular. Sometimes
the central part is flattened, and the sides turned up, so
that the valve resembles the cover of a pill-box, in which
case the cavity will be cylindrical. Then, again, the
valve may be square, triangular, round, heart-shaped,
boat-shaped, etc. In many species of Diatoms the
markings are so minute that they can only be made out
with the highest powers of the microscope ; in others a
very moderate power suffices to exhibit the lines and
dots in patterns which rival the most elaborate works of
art. (Figs. 32, 33, 34.)

In the living state Diatoms are found abundantly in
every pond, rivulet, ocean, and rock-pool. In some
parts of the world they form immense deposits.

A mud bank in Victoria Land, 400 miles long and 120
broad, is composed of silicious valves of Diatoms. In
Sweden and Norway, under the name of bergh-mehl,
they are used for mixing with flour for bread in seasons
of scarcity. Under the cities of Richmond and Peters-
burgh, Virginia, is a deposit twenty feet thick, while the
polishing slate of Bilin contains Diatoms so small that in
a single cubic inch 4O,ooo,ooo,cxx),ooo (forty trillions) are
found.

94

THE SCIENCE OF LIFE.

FIG 32. — Arachnoidiscus Ehrenbergii.

The Arachnoidiscus Ehrenbergii, (Fig. 32,) is common
on the coast of California, attached to sea-weed. Its gen-
eral appearance
is that of a glas-
sy pill-box. The
figure shows one
of the ends, or
frustules, covered
with delicate tra-
cery like a spi-
der's web, by
which the genus
gets its name,
from arachne, a
spider, and disc-
us, a disk. FlG- 33 -Heliopelta.

PROTOPHYTES.

95

The Hdiopelta, sun-shield, (from helios, the sun, and
pelta, a shield, (Fig. 33,) is a most beautiful disk, whose
markings form a regular star, the number of whose rays
determine the species.

The Diatoma vulgare, (A., Fig. 34,) is a quite common

FIG. 34.— A. Diatoma vulgare : a. Side view of frustule ; b. Frustule undergoing
self-division. B. Grammatophora serpentina. a. Front and side views of single frus-
tule. b. b. Front and end views of divided frustule. c, A frustule about to undergo self-
division. </. A frustule completely divided. C. Isthmia nervosa.

form. The frustules often hang together, forming zig-
zag chains by rapid self-division.

Some species of Grammataphora have delicate striae
on the borders of each valve, which are used as tests of
microscopic excellence.

The Isthmia nervosa has a remarkable areolated
structure, which will repay careful examination. In its
growth two cells form within the valves, and, as they

96 THE SCIENCE OF LIFE.

enlarge, break forth, but the silicious hoop which joined
the new frustules to the old one remains attached for a
time round one of them, causing some to appear trunc-
ated instead of round.

The genus Navicula is so called from its resemblance
to a boat or little ship, (naus, a ship.) They are found
both living and in a fossil state. Some are striped lon-
gitudinally, and some transversely ; some are shaped like
an old-fashioned letter S, as the Pleurosigma, in which
the striae are resolved by a highly magnifying power into
hexagonal dots.

10. In the Protophytes we see the endowments of
simple vegetable cells. A piece of bioplasm, or living
tissue, transforms its outer layer into cellulose, and
forms chlorophyll or starch in its interior, absorbing new
pabulum continually, and casting off the old effete atoms.
The relationship of each family is seen by these func-
tions common to all. Each species of each family has,
however, its own peculiarities, which distinguish it from
all others. The Protococci remain rounded cells, but
the Oscillatoria, Confervaceae, etc., have an instinct for
elongation, so that they become tubular, and for distrib-
uting endochrome in characteristic spiral patterns, vary-
ing in each species, while the Diatoms appropriate silica
from their pabulum to harden the cellulose envelope,
and arrange it in their frustules atom by atom, each
species after its own pattern, and all with marvelous
regularity and beauty. The Monistic theory of the
universe has no satisfactory reason to give for the exist-
ence of such varied tendencies. Schleiden has well said,
" We do, indeed, see into the mechanism of the puppet ;

PROTOPHYTES. 97

but who holds the strings and directs all its motions to
One Purpose? Here closes the office of the naturalist;
he turns from the world of space and lifeless matter
upward to where, in holy anticipation, we seek the Ruler
of worlds." *

* Schlieden's " Poetry of the Vegetable World."

98 THE SCIENCE OF LIFE.

CHAPTER VII.

THALLOGEN3.

Thus Nature varies ; man and brutal beast,
And herbage gay, and silver fishes mute,
And all the tribes of heaven, o'er many a sea,
Through many a grove that wing, or urge their so:ig
Near many a bank of fountain, lake, or rill,
Search where thou wilt, each differs in his kind,
In form, in figure differs. — LUCRETIUS.

1. THALLUS-PLANTS, called also Thallogens, or Thai-
lophytes, (from thallos, a frond, or green leaf; genein,
to produce, phyton, a plant,) have no true vascular sys-
tem, but are composed of cells of various sizes, forming
membranous expansions, or filaments more or less sim-
ple, branched, or interlacing. They differ from Proto-
phytes by the more intimate union of cells in their
structure. In some of the Protophytes there is an ad-
hesion of the cells by a fusion of their gelatinous invest-
ment, yet each cell is a repetition of the former one, and
is capable of living independently if detached, so that
each answers to the designation of a unicellular, or
single-celled plant. In the Thallogens the cells are not
only closely united, but exhibit a differentiation in struct-
ure or function, and a relation of mutual dependence,
constituting each plant (not each cell) an individual.

2. The higher Alga, or Sea-weeds, the Lichens , and
the Fungi may be regarded as Thallophytes, although

THALLOGENS. 99

some species may present many points of resemblance
with the simple Protophytes.

3. The ALG^E, or Sea-weeds, have been divided into
three orders, the Red, the Olive, and the Green Sea-
weeds— Rhodospermeae, Melanospermeae, and Chloros-
permeae. " The latter order generally includes the Con-
fervoid and other families which we have considered as
unicellular plants. When we examine the higher Sea-
weeds, we find a certain foreshadowing of the distinction
between Root, Stem, and Leaf, which is characteristic
of still higher types. This sort of unconscious prophecy
of higher forms to come is by no means uncommon in
other classes both of plants and animals, and affords
another proof that living things have been formed on
an intelligent plan. In the Sea-weeds, however, the
apparent distinction of stem and root serves for little
else than the mechanical attachment of the plant. There
is no departure from the cellular type, the only modifi-
cation being that the layers of cells are of different sizes
and shapes.

4. The Olive Sea-weeds, or Fucoids, (Melanospermce^
often grow to a considerable size, attached by sucker-like
roots to the rocks, and, in some cases, buoyed up by air-
bladders. Others are parasitical. The fructification of
many species in this group is sexual. In the common
bladder-wrack, Fucus vesiculosus, the reproductive organs
are on different plants, but in other species, as Fucus
senatus, they are both together, the one olive-green, the
other orange-yellow. The " receptacles " are at the ex-
tremities of the fronds, and may be known to be mature
by each discharging little gelatinous masses adhering-

100

THE SCIENCE OF LIFE.

round its orifice. If now a section is made through it,
it will be seen to be a cavity lined with filaments, some

of which p r o j e c t
through the pore.
The filaments, or an-
theridia, are chains
of cells containing
antlierozoids. These
are yellow oval bod-
ies, with two thread-
like appendages,
which, when liber-
ated by the bursting
of the cell, have a
spontaneous and rap-
id motion around the
sporangia, (or parent
cells of the germs,)
which they fecun-
date. These sporan-
gia are pear-shaped
bodies lying near the

fiG. 35. — section of receptacle of Fiicus platycarpus,
lined with filaments containing antheridial cells and walls of the Cavity, Or

sporangia.

receptacle, and each

one produces, by fission, a cluster of eight cells, or octo-
spores. (Fig. 35.)

5. Among the red Sea-weeds, or Rhodospermecz, are
various simple but beautiful forms, eagerly sought for by
sea-side collectors for albums. They live generally in
deeper water than other sea-weeds, and show their rich-
est tints when growing in the shade. The genus Poly-

THALLOGENS. 101

siphonia contains many species, some small and delicate,
or long and filmy, and of various tints of brown or vio-
let. The fronds are thread-like and jointed ; the joints
striped, since the stem is composed of parallel tubes or
siphons, from whence its name, (poly, many ; siphon,
tube.) The fructification is twofold, on distinct plants:
i.) Ceramidia, or urn-shaped cells containing pear-shaped
spores; 2.) Tetraspores, or groups of four spores, imbed-
ded in swollen branchlets. The genus Ceramium is
thread-like, jointed, branched, with repeated forkings.
The tips of the filaments are always forked, and often
curl toward each other. The fruit is of two kinds :
I.) Berries, or capsules, containing seeds, and called
favellce. 2.) Tetraspores, or groups of four seeds, im-
mersed in the substance of the branch, and surrounding
it in a whorl. Another beautiful and not uncommon
genus, found at low-water mark, or cast up after a storm,
is Ptilota, (from a Greek word signifying " pinnated.")
It has many small branches, or pinnae, and these again
are cut into smaller divisions, or pinnula. At the top of
the latter is the fructification, consisting of minute cap-
sules, or favellce. Some plants also contain tetraspores.
Corallines are a family of red Sea-weeds whose tissue is
consolidated by calcareous deposit. The arrangement of
tetraspores in the red Algae is illustrated by Fig. 36.

6. The class of LICHENS consists of cellular plants of
very simple structure. They form irregular patches,
generally dry, upon stones, trees, etc., which they deco-
rate with various colors. They are found in all climates.
Some are used in medicine, as the Iceland Moss, (Cetra-

ria Islandica;} others, as the Orchil, produce a valuable
9*

IO2

THE SCIENCE OF LIFE.

dye, and one species, Leonora esculenta, found in the
Desert of Tartary, seems to fall from the sky as a mirac-
ulous manna. Men and beasts may be nourished on it.

FIG. 36.— Arrangement of tretraspores, in Carpocaulon mediterraneum : A. Entire
plant. B. Longitudinal section of branch. (N. B. Where only three tretraspores are seen
it is merely because the fourth did not happen to be so placed as to be seen at the same
view.)

It is in the form of globules, varying from the size of a
pin's head to that of a hazel nut ; and as it grows freely,
not being attached to any substance, it is readily driven
by the wind from one place to another.

The thallus of Lichens may be of various sizes, forms,
and colors. (Fig. 37.) Its fruit is called Apotheceia, and
forms cups, or shields, of various forms, often colored
bright red, yellow, gray, or black. When these are di-
vided by vertical sections they are found to contain a

THALLOGENS. 103

number of asci, or spore-cases, arranged vertically among
filaments which are termed paraphyses. The fecundating

a b f g d e c

FIG. 37. — Lichens, a. Cladonia, with scarlet conceptacles. b. Usnea. c. Sticta.
d. Parmelia. e. Vertical section of receptacle, f. Same highly magnified, with thecse
and paraphyses. g. Double spore.

apparatus is called the Spermogonia, and consists of small
rounded or oblong organs, lodged in particular tubercles
or immersed in the superficial layers of the thallus. The
cellular filaments of the spermagonia give off minute
oval bodies, called spfrmatia, which are analogous to the
antherozoids of Algae, but differ in being destitute of
spontaneous motion.

7. The FUNGI form an extensive class of primitive
organisms, generally ranked as plants, but which have
so many peculiarities as to entitle them to be considered
apart. We should not greatly err if we regard them
as a third type of living things, differing both from ani-
mals and vegetables. They have no chlorophyll, as green
vegetables have, and which enables them to break up
carbonic acid. (Chap. VI, Sec. 2.) Light is not essen-
tial to the activity of Fungi, as it is to that of vegeta-
bles. They are incapable of assimilating inorganic food,
but live upon organic substances. They are the agents
of fermentation and of putrefaction, and their principal

104

THE SCIENCE OF LIFE.

office seems to be to break down and to restore to the
inorganic world the effete formed material of animal
and vegetable life. Mushrooms, Puff-balls, Molds, and
the Rust of grain are examples of Fungi.

8. The simplest forms of Fungi resemble Protophytes,
except in the absence of chlorophyll, either green or red.
Recent investigations have indicated that those which
seem most simple are but imperfectly developed states
of other species. The Torula cerevisicz, or yeast-plant,
which is the cause of fermentation in solutions of sugar,

FIG. 38. — Appearances presented by Bacteria under the microscope. At c, are iso-
lated Bacteria ; at d, they are arranged round a center ; while at a they appear in long
strings ; at e is observed a solitary torula. All highly magnified.

and Bacteria (Fig. 38) of various forms, which cause pu-
trefaction in animal substances, appear to be varieties, or
stages, in the development of some of the u molds," or
microscopic fungi, many of which are capable of poly-
morphism, or the assumption of many forms. In some
kinds of fungi the bioplasm shows amceboid movements,
having a great resemblance to some of the lower forms
of animal life.

9. Fungi are cellular organisms of variable consistence.
They exhibit two well-defined structures, a mycelium, or
spawn, (Gr. myces, a fungus,) formed of filaments some-

THALLOGENS. 105

times assuming a membraneous, a tubercular, or a pulpy
form, and a fruit, or reproductive structure, which dif-
fers in different tribes. The essential reproductive or-
gans are spores, called also conidia, usually four, or some
multiple of four, attached to the cellular tissue, and sup-
ported on simple or branched filaments, (called conidio-
phores, or basidia,} or contained in sacs, (theca, cystidia,
or asci ; all of which words, derived from the Greek,
have similar meaning.)

10. Fungi have been divided into six orders, as follows :

i.) Hymenomycetes, (Gr. hymen, a membrane, and myces,
a fungus.) Mycelium inconspicuous, bearing fleshy fruits
which expand so as to expose the spore-bearing mem-
brane to the air. Mushrooms are well-known examples.

2.) Gasteromycetes, (Gr.gaster, belly.) Fructifying sur-
face inclosed, as in Puff-balls.

3.) Coniomycetes, (Gr. konis, powder.) The spawn or
vegetative part is reduced to a minimum, and the abun-
dant spores form a dusty or sometimes a gelatinous
mass. The rust and bunt of wheat and other grains are
instances.

4.) Hyphomycetes, (hyphao, to weave.) The vegetative
part consists mostly of loose threads, as the naked seed
Molds.

5.) Ascomycetes, (askos, a bag.) The sacs, or asci, con-
taining the sporidia are either packed into an exposed
hymenium, or line the interior of the fruit-bearing cysts,
as Truffles, etc.

6.) Physomycetes, (physa, a bladder.) Mycelium fila-
mentous, bearing sacs, containing minute iporules, as the
common Bread-mold.

io6 THE SCIENCE OF LIFE.

11. The difficulty of determining what forms are to be
regarded as species, and what as mere varieties, finds
many illustrations in the class of Fungi. We know but
little of the influence of external conditions in modifying
forms, and the forms of fungi are so exceedingly unsta-
ble that the best observers are often at a loss. Yet this
variability is only one of degree, since all living beings are
more or less subject to modifications of form by external
influences. It is this variability which has rendered the
Darwinian hypothesis of evolution by " the survival of
the fittest " so plausible a theory. But notwithstanding
this capability of modification, there is still a certain fun-
damental and specific type for each assemblage of forms,
and the amount of variability is strictly limited.

12. Many diseases of plants and animals are associated
with the growth of Fungi. The " mildew " (Puccinid)
and " rust " (Uredo) of wheat, etc., the potato blight,
(Peronospora,) the disease in Silk-worms called Muscar--
dine, (Botrytis,) the false membrane in diphtheria, the
white patches in aphthae, or thrush, and many skin af-
fections, afford examples. Pyaemia is supposed to result
from bacteria in the blood, and many epidemic diseases
have been ascribed to similar origin. The prevalence of
atmospheric changes, however, and variations in external
conditions, as light, heat, moisture, etc., have much to
do in predisposing both animal and vegetable tissues to
disease, and in producing epidemics. Since the office
of Fungi is to remove decaying or effete organic matter,
we must discriminate between those diseased conditions
which provide a habitat for fungi and the effects pro-
duced by the fungi themselves

THALLOGENS. 107

13. The excessively minute and almost vapor-like
sporules of fungi float about in the atmosphere in count-
less numbers, only waiting for a fitting soil in which to
grow. As long as there is no refuse matter to be re-
moved these scavengers are unemployed, but the small-
est quantity of decaying animal or vegetable matter left
exposed becomes covered with spores, which develop
with astonishing rapidity. A scanty number of spores,
only to be detected by careful research, will in a few
days, and sometimes in a single night, give birth to
myriads, to repress or remove the nuisances referred to.
When the offal diminishes fewer of the spores find soil
on which to germinate, and when all is consumed the
active legions return to their latent or undeveloped
state. Like Milton's spirits —

So thick the aery crowd

Swarmed and were straitened ; till, the signal given,
Behold a wonder ; they but now who seemed
In bigness to surpass earth's giant sons,
Now less than smallest dwarfs.

14. In the chapter on the Protophyte type of vegeta-
ble life, we considered the bioplasm, or living matter,
differing in each kind, yet agreeing in one particular,
namely, that each cell exhibits a repetition of the form
and power of the parent-cell. In the Thallogens we find
another idea predominating, or rather two leading ideas,
the co-ordination of many cells in the structure of one
individual, and the differentiation of cells in form and
function, analogous to the division of labor in human
society. Respecting the first, Joseph Cook has well re-
marked, in his axiomatic style : " Living tissues are co-

io8 THE SCIENCE OF LIFE.

ordinated according to definite plans. As every change
must have an adequate cause, we are compelled to infer
the existence of a co-ordinating force behind the action
of the bioplasts in each organism. That force is the
cause of form in organisms. It has as many types as
there are types of organisms, vegetable and animal." *
The same subtle power which co-ordinates, also differen-
tiates the cells. This power resides in the original germ,
before the organization of the individual form, and is
what we have already defined as Life, and is not explica-
ble by physical causes. "Collocation of parts in an
organism is precisely what materialism has never yet
explained." f

* " Heredity," by Joseph Cook, p. 46. f Cook's " Biology."

ACROGENS. 100

CHAPTER VIII.

ACROGENS.

Flower in the crannied wall,

I pluck you out of the crannies,

Hold you here in my hand,

Little flower, root and all,

And if I could understand
What you are, roots and all, and all in all,
I should know what God and man is.

— TENNYSON.

1. IN the type of Acrogens the instinct of develop-
ment, or evolution of cells, is seen only at the summit
or apex of the stem. Cells in other parts of the plant
may enlarge, but do not multiply themselves. These
plants generally have distinct stems and leaves, with
stomata, (Chap. IV, Sec. n,) a certain amount of vascu-
lar tissue, (Chap. IV, Sec. 10,) and theca, or cases con-
taining spores. The Stoneworts, (Characcej) the Liver-
worts, (Hepaticce^) the Horsetails, (Equisetacecs^) the
Ferns, (Filices]) and the Mosses, (Musci^) are the prin-
cipal families of Acrogens.

2. The Stoneworts (CHARACE^E) have generally been
regarded among Algae, or water-weeds. But they differ
greatly from Algse in having a distinct axis of growth,
and appendages. The axis may be a simple tube, (Ge-
nus Nitella^} or a tube with a cortical layer of smaller
tubes surrounding it, (Genus Chara^) They are found
in ponds and rivers, in tangled masses of a dull green
color. Each plant is hardly thicker than a stout needle,

10

110

THE SCIENCE OF LIFE.

but may be three or four feet long. It has rootlets
springing from the axis, by which it is fixed in the
muddy bottom of the stream, etc., but the main source
of its nutriment is the water in which it lives. It pos-
sesses chlorophyll, and in consequence decomposes car-
bonic acid under sunlight, retaining the carbon to form
part of its own substance, and giving off the oxygen.
The branchlets (or leaves, as they are called) are grouped
in whorls, or spring from the same height in the stem.

FIG. 39.— Nitella flexilis : A. Stem and branches of the natural size. a. b. c. d. Four
verticils of branches issuing from the stem. e.f. Subdivision of the branches. B. Portion
of the stem and branches enlarged, a. b. Joints of stem. c. d. Verticils, e.f. New cells
sprouting from the sides of the branches, g. h. New cells sprouting at the extremities of
the branches.

and at regular intervals. (Fig. 39.) The main stem is
called the axis, and a branch, when it exists, is a second-

ACROGENS.

Ill

ary stem. The appendages are the leaves, branches,
rootlets, and reproductive organs. The points on the
axis, or stem, from which the appendages spring, are
called nodes, the intervening parts being the internodes.
In Chara the internodes have a spiral striation. Growth
takes place at the apex by the development of new
nodes and internodes. Each internode is formed by the
growth and elongation of one cell.

The terminal bud is formed by a single cell, which di-
vides by fission into two, one of which forms the inter-
node, while the other sub-
divides into lateral cells,
which, by division, produce
the appendages. In the lat-
ter, after a certain stage,
the terminal cell is inca-
pable of further division,
but in the stem the proc-
ess continues indefinitely.
. 40.)

FIG. 40. — Growing Point of Chara.
The reproductive Organs <*. Terminal cell dividing, b. Cells form
, ing youngest node, and which by their fis.

in these plants are Of tWO sion will give rise to a whorl of appendages.
i • j i . • c. c. Internodal cells, d. Incipient append-

kinds, oval sporangia, or agss. ,. Same farther advanc^ £££
spore-fruits, and antheridia. ™"ai ceil dividing.
The latter are smaller than the sporangia, and globular,
and contain filaments whose cells are changed into little
ciliated bodies called anther ozoids, (Fig. 41.)

The growing spore from the sporangium gives off two
filaments resembling the hyphse in fungi, one of which
serves as a temporary root, and a cell in the other pro-
duces a group of lateral projections from which the young

112

THE SCIENCE OF LIFE.

Chara springs. This temporary structure is termed the
pro-embryo.

In Chara vulgaris the circulation, or movement, of
bioplasm in vegetables was first
discovered. (Chap. II, Sec. 7,
and Chap. IV, Sec. 6.)

3. The Liverworts, or HEPA-
TIC^, form a class or group of
plants generally considered in-
termediate between Lichens
and Mosses. They are fur-
nished with leaves, or lobed
fronds, with rootlets on the
F.G. 4i.-portion of Antheridium under surface, which send up

of Chara. x. Several jointed filamnts jfc - • { d

attached to a vesicle. 2. End of one J o

of the tubes, a spiral thread escaping, shield-like disks, bearing an-

3. A tube nearly empty. 4. An an-

therozoid with its cilia. theridia, or radiating bodies,

bearing at first archcgonia, or female organs, and after-
ward sporangia, or spore-cases. (Fig. 42.)

The arrangement of
the stomata, or breath-
ing pores, in these hum-
ble plants is far more
complex than we find
it in others. The leaves
of all the higher plants
have cavities, or air-

SDaCCS Communicating

*•
with the external WOrld

by openings, or pores, which are guarded by elastic
cells ; but in Marchantia polymorpha the green sur-

FIG. 42.— Frond of Marchantia polymorpha,
with gemmiparous conceptacles, and lobed re-
ceptacles bearing pistillidia.

ACROGENS.

face of the frond is seen by a low magnifying power to
be divided into diamond-shaped spaces, containing an
opening in each. On making a thin section, as in Fig. 43,

FIG. 43. — A. Portion of frond of Marchantia polymorpha seen from above, a. a. Loz-
enge-shaped divisions, b. b. Stomata seen in the center of the lozenges, c. c. Greenish
bands separating the lozenges. B. Vertical section of the frond, showing a. a. the dense
layer of cellular tissue forming the floor of the cavity d. d. b. b. Cuticular layer, forming
its roof. c. c. Its walls, f.f. Loose cells in its interior, g. Stoma divided perpendicu-
larly, h. Rings of cells lorming its wall. z". Cells forming the obturator ring.

each of these stomata will be seen to form a sort of
shaft, or chimney, of four or five rings, or courses, of
cells, the lowest ring regulating the aperture into the
leaf-grottoes below.

The spores of Marchantia are attached to elaters, or
spirally-coiled elastic fibers, whose extension scatters the
spores.

3. The EQUISETACE^:, or Horsetails, are found in
most parts of the world, save Australia and New Zea-
land. They generally grow in wet places, sending up
shoots from a creeping stem, or rhizome. The cuticle is
remarkable for the great quantity of silica contained in
it. The particles of this mineral, each having a double
axis of refraction, are arranged in rows parallel to the
axis, and are beautiful objects under the microscope,

with polarized light. The abundance of silica has led
10*

THE SCIENCE OF LIFE.

to some of these plants being used as natural files for

polishing various articles.

The shoots are jointed, each articulation having a

toothed membrane-
ous sheath, and hav-
ing whorls of branch-
es and branchlets.
The fructification is
in the form of termi-
nal cones, with scales
bearing spore-cases,
and opening by a

FIG. 44.— a. Equisetam arvense. o- Equisetum syl-

vaticum. c. Section of the spike, d. A sporange. e. A longitudinal fisSUTC.
spore with its elaters coiled.

Each of the spores

has a pair of spiral filaments, with clubbed ends, and
attached by their center, so as to look like four stamens.
(Fig. 44.)

4. FERNS in tropical countries are sometimes rivals of
the most beautiful Palms, having trunks varying from
two or three to sixty or eighty feet in height, formed of
the consolidated bases of the fronds. In these Tree-
ferns the fronds are either repeated in whorls, or they
form a tuft at the summit, constituting in the latter case
a collection of whorls with suppressed internodes. In
the ordinary ferns, or brakes, of temperate climes, the
stem is an underground one, or rhizome, and the dispo-
sition of the fronds is seldom observed.

The epidermis of the stem is of a brownish hue, and
the general cellular structure, or parenchyma, consists of
many-sided nucleated cells, containing chlorophyll and
starch granules. There are also vessels (annular, spiral,

ACROGENS. 115

and scalariform, or ladder-like) and fibrous or woody
tissue, forming together the sclerenchyma, or harder tis-
sues. (Chap. IV, Sees. 6 to 10.)

In Fig. 45 the acrogenous growth of a fern is illus-
trated, together with the metamorphosis of the terminal

FIG. 45.— Diagram, showing the mode of growth in the stem of a Fern. A. B. C.
Stems of ferns showing successive stages of growth, a. a. a. Terminal cells, the latter
just after being produced by division, b. A cell which will give rise to an internode.
c. Shows a ring or cluster of cells giving rise to a node. d. Epidermal cells, e. Parenchyma.
/". Sclerenchyma. g. Scalariform vessels, h- Spiral vessels, k. An appendage, originating
at the node. d. e.f. g. and h. all arise from the multiplication and metamorphosis of the
"growing" cells.

cell into the various tissues. In flowering plants the
terminal cell of the leaf-bud becomes barren, and the
enlargement of the leaf depends on the multiplica-
tion and growth of cells nearer the base ; but in the
fern the leaf-bud grows as the stem does, so that the
peduncle is first formed, then the embryo leaf, then the
pinnules, etc.

Underneath the frond of a fern we may sometimes see
little brown patches. Each patch is a sorus, (sometimes
covered by a membrane called an indusium^] and the
little brown bodies constituting it are sporangia, or
spore-cases, which have been developed from epidermal
cells. An elastic ring (annulus) surrounds each sporan-
gium, and assists in opening it. The growth of these

ii6 THE SCIENCE OF LIFE.

minute spores may be observed by sowing them on a
saucerful of fine mold, covering with a bell-glass or tum-
bler, and keeping it moist, warm, and shaded. A green
film will spread over the soil, which can be taken up,
from time to time, on the point of a knife for microscopic
examination. The little spore swells and bursts, and
throws out a rootlet which gets its nourishment from the
soil. Then a number of delicate cells are formed from
the mother-cell in the spore, making a little green scale,
(the prothalliu m,) which throws out rootlets on its under
side. This prothallium produces two kinds of cells, one
set called antheridia, which contain spiral filaments which
escape to enter the others, called archegonia, or germ-
cells, from which the future fern is reproduced. (Fig. 46.)

The fossil remains of Ferns in the various strata of
the earth's crust are very numerous, especially in the
Coal measures. These deposits exhibit the remains of
many species now extinct. Immense tree-ferns and gi-
gantic Lycopodiaceae (Club-mosses) flourished in an at-
mosphere charged with moisture and carbonic acid gas,
which, by plant assimilation and liberation of oxygen, is
thought to have been purified and prepared for the use
of successive tribes of animals and of man.

5. MOSSES are minute and lowly plants, but they are
by no means insignificant. There are about ten thou-
sand species, some of which are not over a hundredth
part of an inch in height, while others are several inches
high. Mosses have a distinct axis of growth, and the
delicate leaves are arranged with great regularity. The
stem shows some indication of the separation of a cor-
tical, or bark-like portion, from the medullary, or pith-

ACROGENS.

117

like, by the intervention of a circle of bundles of elon-
gated cells, from which prolongations pass into the leaves,
so as to afford them a sort of midrib.

FlG. 46. — Ferns and their parts, a. Fronds and root-stalk, b. Frond, showing the
spore-cases, c. Exterior and interior of seed-vessel, d. Fronds, gradually unfolding, e. A
Theca, or spore-case, before opening, f. A Theca, or spore-case, discharging its spores.
g. Prothallus of its natural size. h. Lower surface of prothallus, much enlarged, showing
the organs whose reciprocal action determines the development of the fern. i. Various
forms of one of these organs when in movement. j\ Inclosed vesicle, in which the devel-
opment of the fern commences.

The root-fibers are long tubular cells, quite transpa-
rent, within which the circulation of the bioplasm may
be seen. Dr. Hicks has observed portions of the inclosed
bioplasm detached, and having amceboid motions.

ii8 THE SCIENCE OF LIFE.

The stems of Mosses usually terminate in filaments,
or foot-stalks, supporting an urn-shaped vessel closed by
a lid, (operculum!) which is covered by a cap, or hood,
(calyptra?) Under the operculum, the edge of the urn is
a beautiful toothed fringe, (the peristome!) and within the

FIG. 47. --Structure of Mosses. A. Plant of Funaria hygrometrica, showing, f. the
leaves ; u. the urns supported upon the setae, or footstalks, j, closed by the operculum,
0, and covered by the calyptra, c. B. Urns of Encalyptra vulgaris^ one of them closed
and covered with the calyptra, the other open. u. u. The urns. o. o. The opercula. c. Ca-
lyptra. p. Peristome. s. s. Setae. C. Longitudinal section of very young urn of Splach-
num. a. Solid tissue forming the lower part of the capsule, c. Columella. /. Loculus,
or space around it for the development of the spores, e. Epidermic layer of cells, thick-
ened at the top to form the operculum, o. p. Two intermediate layers, from which the
peristome will be formed, s. Inner layer of cells forming the wall of the loculus.

urn, or spore-capsule, (sporangium^) are double-coated
spores. (Fig. 47.)

In developing into new plants, the outer coat of the
spore bursts and the inner wall protrudes. New cells
grow from the extremity, forming a filament, whose cells
at certain points multiply by subdivision, so as to form
rounded clusters, like the prothallus of Ferns, or the pro-

ACROGENSVv ' I IQ

embryo of Chara, from each of which an independent
plant may arise.

The urn, or capsule, is not the real fructification of a
moss, but its product, since Mosses, like Liverworts, etc.,
possess both antheridia and pistillidia, although they are
often inconspicuous. They are found either together,
or on different parts of the same plant, or on different
plants. They are usually situated at the bases of the
leaves, close to the axis. The antheridia are globular
or elongated capsules containing sperm-cells, each of
which produces a moving antherozoid, which escapes at
the summit of the capsule. Hair-like filaments (para-
physes) around the antheridia are considered to be ster-
ile or undeveloped antheridia. The archegonia are like
those of the Hepaticeae, and when fertilized the embryo-
cell develops by cell-division into a conical body ele-
vated upon a stalk. This tears the walls of the flask-
shaped archegonium by a circular fissure, carrying the
upper part as the calyptra, or hood of the " urn," while
the lower part remains as a sort of collar around the
stalk.

6. The characteristics of the type of Acrogens are the
growth of cells at the summit only ; the appearance of a
distinct cortical portion, or epiderm, and of vascular and
fibrous tissue ; and a sort of alternation of generations in
the provision of a prothallus, so that plants of this type
may not improperly be designated Prothallus plants, as
the higher types are sometimes known as Monocotyled-
onous, or Dicotyledonous plants.

7. As an illustration of the reflections natural to a
well-regulated mind from the study of natural objects,

120 THE SCIENCE OF LIFE.

oven of minute and apparently insignificant Acrogens,
an incident in the life of Mungo Park is appropriate.
This enterprising traveler, during one of his journeys
into the interior of Africa, was robbed and stripped by
banditti. When the robbers had left him, he says : " I
sat for some time looking around me with amazement
and terror. Whichever way I turned, nothing appeared
but danger and difficulty. I found myself in the midst
of a vast wilderness, in the depth of the rainy season,
naked and alone, surrounded by savage animals, and men
still more savage. I was five hundred miles from any
European settlement. All these circumstances crowded
at once upon my recollection, and I confess that my
spirits began to fail me. I considered my fate as cer-
tain, and that I had no alternative but to lie down and
perish. The influence of religion, however, aided and
supported me. I reflected that no human prudence or
foresight could possibly have averted my present suffer-
ings. I was indeed a stranger in a strange land, yet I
was still under the protecting care of that Providence
who has condescended to call himself the stranger's
friend. At that moment, painful as my reflections were,
the extraordinary beauty of a small moss irresistibly
caught my eye, (I mention this to show from what
trifling circumstances the mind will sometimes derive
consolation,) and, though the whole plant was not larger
than the top of one of my fingers, I could not contem-
plate the delicate conformation of its root, leaves, and
fruit without admiration. Can that Being (thought I)
who planted, watered, and brought to perfection, in this
obscure part of the world, a thing which appears of so

ACROGENS. 121

small importance, look with unconcern upon the situa-
tion and sufferings of creatures formed after his own
image? Surely not. Reflections like these would not
allow me to despair. I started up ; and, disregarding
both hunger and fatigue, traveled forward, assured that
relief was at hand, and was not disappointed." Such
views of the universe and of its Creator infuse strength
into the human soul, and give a vigor to human charac-
ter which is impossible otherwise. For the good-order-
ing of human life they are infinitely above all Monistic
speculations and theories of Evolution, which belittle
or lose sight of the individual in a romantic sentiment
respecting primordial and progressive development of
all.

11

122 THE SCIENCE OF LIFE.

CHAPTER IX.

ENDOGENS.

What time this world's great workmaister did cast
To make all things such as we now behold,
It seems that He before His eyes had plast
A goodly patterne, to whose perfect mould
"Tie fashioned them as comely as he could,
That now so fair and seemly they appear
As naught may be amended anywhere.

— SPENSER.

I. ENDOGENOUS plants have no separable bark, nor
distinct concentric circles in the stem. Their fibro-
vascular bundles, consisting of spiral and porous vessels
and woody fibers, descend from the leaves downward,
converging at first toward the center, but afterward di-
verging outward until they reach the roots, or attach
themselves to the hardened tissue of the outer or corti-
cal layer, corresponding to the bark in Exogens, but
harder than the rest of the stem, and inseparable from
it. It used to be thought that the woody portion was
added to the center, and pushed the first-formed fibers
toward the circumference; hence the term Endogenous,
(endon, within, and gennao, to produce.) In strict scien-
tific accuracy the term only applies to the fibers at the
early part of their course, since in the latter part they
become blended in the cortical layer, forming a tough
net-work. The center of the stem when young is filled
with cells which sometimes disappear, except at the
nodes, leaving the stem hollow, as in Grasses.

ENDOGENS. 123

The embryo of Endogens has but a single cotyledon,
or seed-lobe, on which account they are often termed
Monocotyledons. Acrogens have no seed-lobe, but cel-
lular spores, and are called acotyledons, (from the Greek
a, privative, and kotyledon, something hollow,) while Ex-
ogens have two seed-lobes, and are dicotyledons.

The veins in the leaves of Endogens are generally
parallel, or straight, (Fig. 48,) and do not
form a net-work, and the parts of the flower
are arranged in sets of threes, or of some
multiple of three.

2. Exceptions to the parallel venation of
leaves in Endogens have been placed by
Lindley in a class by themselves — the Dic-
tyogence, (from dictyon, a net, and gennao, to
produce ;) in allusion to the reticulation of
the leaves. They comprise the Yam tribe,
(Dioscoreacece^) the Sarsaparilla family, (Smi-
lacece^) and the Trillium family, ( Trilliacece.}
The other classes or sub-classes are, I. Pe-
taloidece, or Florida, in which the flowers
consist either of a colored perianth (a floral
envelope) or of scales arranged in a whorl.
2. Glumiferce, in which the flowers have
imbricated bracts or scales, called glumes.
This includes the two orders of grasses and
sedges. The Petaloidece are divided into
three sections: i. Epigynce, having perfect
flowers, and a superior perianth, (ovary infe-

J FIG. 48.-— Endog-

rior,) as Orchids, Gingers, Irids, Amarylids, enous Leaf,

T, ing parallel vena-

etc. ; 2. Hypogynce, having perfect flowers tion.

124

THE SCIENCE OF LIFE.

and an inferior perianth, (ovary superior,) as Lilies,
Rushes, and Palms ; 3. Incomplete, with imperfect flow-
ers, without a proper whorled perianth, as Screw-pines
and Arums.

3. GRAMINE^:, the Grass Family, is one of the most
important orders in the vegetable kingdom, whether we
regard it as supplying food for man or herbage for ani-
mals. Grasses are found in all quarters of the globe;
and are said to form about i-22d part of known plants.
There are about 4,000 species, and their structure is the
most simple of the higher forms of vegetation. Their
stems form protecting sheaths to the growing shoots,
and have alternate leaves. Their flowers, or glumes,
present many varieties, producing the distinctive char-
acters of families or tribes, and genera. Among the
grasses are the nutritious cereal
grains, as Wheat, (Triticum,) Oats,
(Avena^) Barley, (Hordeum,) Rye,
(Secale,) Rice, (Oryza,} Maize or In-
dian Corn, (Zea,) etc. Here, also,
are found various pasture grasses, as
Rye-grass, (Lotmm,) Timothy-grass,
(P/tleum,) Meadow-grass, (Poa,) etc.
(Fig. 49.)

The cereal grains have been so
generally distributed by man that
all traces of their native country are
lost. They seem to be examples of permanent varieties
or races preserved by cultivation.

The grains, or seeds, of many kinds are used for food,
since they contain a large amount of starch and gluten.

FIG. 49.— Wheat, Barley,
Meadow-grass.

ENDOGENS. 125

Sugar is also obtained from many grasses, as the Sugar-
cane, (Saccharum officinarum^) Sweet Sorghum, (Sorghum
saccJiaratum^) etc.

Grasses contain a large quantity of silicious matter in
the epidermis of their stalks, which sometimes accumu-
lates in the joints, as the Tabasheer in the joints of
Bamboo, (Bambusa?) This latter is a tree-like grass,
sometimes growing fifty or sixty feet high. It is applied
to an almost endless variety of purposes. The Chinese
use it, in one way or other, for nearly every thing they
require. The sails of their ships, as well as their
masts and rigging, and articles of furniture, as mats,
screens, chairs, tables, bedsteads, and bedding, are all
made out of the Bamboo, which is cultivated with great
care.

The stems of some grasses run under-ground, and are
useful in consolidating the sand of the sea-shore. This
property renders some grasses (as Triticum repeus) diffi-
cult to exterminate.

4. SEDGES, (Cyperacece^ are grass-like herbs, with
angular stems and narrow, tapering leaves wrapping
found the stem, but without the slitting sheath. Their
flowers are borne on bracts, or scales, united in an im-
bricated manner so as to form a spike. In Lapland they
equal the grasses in number, but the proportion de-
creases toward the equator. Few plants of this family
are attractive to the eye, but many of them are useful.
The creeping stems of Carex arenaria bind the shifting
sands on the shores of Brittany and Holland into a wind-
defying mass. The Papyrus antiquorum of the Nile (the

Bulrush of Scripture) belongs to this family. It for-
11*

126

THE SCIENCE OF LIFE.

merly furnished the world with paper, besides being
used for making boats, ropes, etc. (Fig. 50.)

,:

FIG. 50. — The Papyrus of the Nile.

FIG. 51. — Cocoa-nut Tree, (Cocos nuctfera,)
and Plantain, (Musa Paradisiacal)

5. Linnaeus, the great Botanist, called Grasses the
plebeians, and PALMS the princes, of the vegetable

ENDOGENS. 127

world. The latter are for the most part trees of gigan-
tic growth, often reaching dimensions unknown among
other plants. They are used for supplying food and for
forming habitations. The fruit of some is edible, while
that of others is hard. Many supply oil, wax, starchy
matter, and sugar, which is fermented to form an intoxi-
cating beverage. Their fibers make ropes, and the re-
ticulum about their leaves is sometimes manufactured
into brushes.

The Date palm, (Phoenix dactylifera,) which supplies
food to so many of the inhabitants of Arabia and Africa,
is considered to be the Palm of the Bible. The Cocoa-
nut palm (Cocos nuciferd) is one of the most useful,
supplying the South Sea Islander with food, clothing,
houses, utensils, ropes, oil, sugar, wine, and Palm cab-
bage from the terminal bud, etc. (Fig. 51.)

Sago and other starchy matter is obtained by bruising
and washing the cellular tissue of many Palms, espe-
cially Sagus Rumphiiy S. lavis and 5. genuina.

6. The BANANA family (Musacecz) contains plants
which furnish a large supply of nutritious fruit, while
their leaves afford valuable fibers. The best known spe-
cies are Musa paradisiaca, or Plantain, and M. sapientum,
or Banana, (Fig. 52 ;) the former a denizen of the Old
World, and the latter of the New. The specific name
of the first originated in a notion of some of the old
botanists that it was the forbidden fruit of Eden. A
quaint writer remarks that it is not likely that a plant so
useful should have been the forbidden fruit. The Ba-
nana supplies the inhabitants of the tropical islands with
wholesome and abundant food, pleasant drink, valuable

128 THE SCIENCE OF LIFE.

medicine, materials for clothing, baskets, mats, and with
almost all other necessaries of their simple life. Musa

FIG. 52. — Banana, (Musa sapientum.)

textilis supplies a flax-like fiber, from which some of the
finest Indian muslins are made.

7. The ARROW-ROOT family, (Marantacea^ the PINE-
APPLE family, (Bromeliacece^) and the GINGER family.
(Zingiberacece^) contain many useful species of Endogens.
Here also are classed many of the showy flowers of our
gardens and hot-houses. The IRIS family, (Iridacece^)
containing the Iris, Gladiolus, and Crocus, etc. ; the
singular aquatic plants of the Hydrocharidaceae, as Hy-
drocharis and Valisneria ; and the AMARYLLIS family,
(Amaryllidacece^) embracing the Daffodil, Amaryllis, and

ENDOGENS.

129

Agave, are of this class. The last-named plant is some-
times called the American Aloe, (Agave Americana,)
and, according to gardening fable, only blooms once in
a hundred years, hence called Century plant. Its large,
hard, spinous leaves grow slowly for years, when sudden-
ly, in the course of a single season, a stem shoots up forty
or fifty feet in height, bearing a crest of flowers. In
Peru and Mexico an intoxicating beverage called pulque
is made from the sap.

8. The ORCHID family (Orchidacece] exhibit the great-

FIG. 53.— Orchids, (Orchidacete.)

est variety of forms and brilliancy of color among all the
vegetable tribes. The flowers often resemble insects, as

130

THE SCIENCE OF LIFE.

butterflies, moths, flies, and spiders ; or birds, as doves
and eagles ; or reptiles, as snakes, lizards, and frogs.
(Fig. 53.) Their spots and colors give sometimes the
appearance of leopard or tiger skins. These resemblances

are indicated in their
generic and s p e c i fi c
names. Some parts of
the petals of these flow-
ers display peculiar irri-
tability, for the purpose
of scattering the fertiliz-
ing pollen. As the vis-
its of insects are often
subsidiary to the fertili-
zation of Orchids, they
have attracted much at-
tention from naturalists.
They abound chiefly in
moist tropical climates.

9. The LlLY family
(Liliacece) includes many
showy garden flowers,
as Tulips, Lilies, Dog-
tooth-violets, and Tube-
roses. (Fig. 54.) It is
divided into several
tribes, as the Onion, or
Squill tribe, the Aspho-
del tribe, the Lily-of-the-
valley tribe, the Aloes
FIG. 54.— The white L:iy, (Luium aidvm.) tribe, and the Asparagus

ENDOGENS. 131

tribe. In the latter tribe are placed the Dragon-trees,
the most gigantic of the order. There is one in the
Island of Teneriffe which is described as seventy feet
high and forty-six feet in circumference at the base.
The flowers are small. From some species of Dragon-
tree the Sandwich Islanders prepare an intoxicating
liquor called ava.

The inspissated juice of several species of Aloe is used
in medicine as a cathartic, and the bulb of the Squill is
imported from the coasts of the Mediterranean, and is
valued for its diuretic, expectorant, and other properties.

A species of Onion called Camass is used by the In^
dians of Oregon as food.

Textile fibers are procured from New Zealand flax
(Phormium) and from the Yucca, or Adam's needle.

10. The SCREW-PINE family (Pandanus) contains sev-
eral species which exhibit a semblance of

instinct in the development of aerial roots
at different distances on the stem, by which
their life is prolonged. Their leaves are
arranged in a spiral, hence the name,
Screw-pine.

11. The ARUM family contains the
Cuckoo-pint tribe, the Bulrush tribe, (Fig.
55,) the Sweet-flag tribe, and the Duck-
weed tribe. In the Duckweed (Lemnd)
we see at a casual glance nothing but a

green scale floating on the water, which is FlG>55'~~]
in reality a compound of both root and stem. A careful
observation in summer may lead to the discovery of mi-
nute straw-colored anthers on the edges of the plants,

132 THE SCIENCE OF LIFE.

and near these a narrow slit, which, on being enlarged,
will show the simple flower, like a membraneous bag,
and containing two stamens and one ovary, with its style
and simple stigma.

IT. Protophytes, Thallogens, and Acrogens have been
classed together in the artificial system of Linnaeus as
Cryptogamia, (from cryptus, hidden, and gamos, nuptials,)
in allusion to the inconspicuous character of their repro-
ductive organs ; while Endogens and Exogens are called
PJianerogamia, (phaneros, visible, and gamos, nuptials,)
since they have perceptible reproductive organs formed
of stamens and pistils. To these essential parts we fre-
quently find two envelopes added, the calyx and corolla.
These parts make up the flower, and the Phanerogamia
are not infrequently known as flowering plants.

The flower consists of whorled leaves placed on an
axis, the internodes of which are not developed. There
are usually four of these whorls. The outer whorl is the
calyx, the next the corolla, the third the stamens, and
the innermost the pistil. In Exogens the calyx is usu-
ally green and the corolla colored, but in Endogens both
frequently display rich coloring, and are apt to be con-
founded, so that the term perianth is usually applied to
the flowers of Endogens, whether colored or otherwise,
(peri, around ; anthos, flower.)

The parts of the calyx, when separate, are called se-
pals, and the leaves of the corolla petals. Stamens have
two parts, the filament, or stalk, and the anther, or
broader portion, corresponding to the folded blade of
the leaf, and containing fertilizing grains called pollen.
The pistil is also made up of two parts, the ovary, con-

ENDOGENS.

FIG. 56.— A. Sectional view of the flower, showing the vertical disposition of the whorls.
(i. Sepal of calyx, b. Petal of corolla, c. Filament of stamen, d. Anther cf stamen.
f. Ovary of pistil, f. Style of pistil, g. Stigma of pistil. B. Plan of the typical flower of
an exogenous plant, showing the horizontal disposition of its parts, a. Sepal, b. Petal.
c, c. Stamens in two distinct whorls, d. Carpel or ovary, inclosing an ovule, attached by
its funiculus. C. Various parts of the clove, a. Flower of the clove or pink. b. Vertical
and middle section of the flower, c. Flower reduced to its male and female portions ; the
stamens are six in number — four large, (in pairs,) and two small. <£ One of the petals.
e. Horizontal section of the ovary, or seed-vessel; showing the insertion of the ovules.
/". Fruit at the moment of expansion, g. Seed, with its funiculus. h. Vertical section of
the seed and its embryonic contents, i. The embryo alone, k. Horizontal section of the
seed and its embryonic contents.

1*5

134 THE SCIENCE OF LIFE.

taining ovules or young seeds, and the stigma, a cellular
secreting body for the reception of the pollen-grains.
This is sometimes sessile, or resting on the ovary, and
sometimes elevated on a stalk, or style. Like the other
whorls, the pistil is made up of one or more modified
leaves, named carpels. (Fig. 56.)

Some flowers have no stamens, and are called female
flowers ; others have no pistil, and are male flowers ;
but both stamens and pistils are always present, either
on the same plant or on different plants. Some flowers
have neither calyx, corolla, nor stamens ; others, neither
calyx, corolla, nor pistil. If they have no corolla they
are incomplete, and if corolla and calyx are both absent
they are naked.

The general axis of inflorescence is called rachis ; the
stalk supporting a flower or a cluster of flowers is a pe-
duncle, and, if small branches are given off by it, they are
called pedicels. Sometimes the floral axis is shortened,
and is flat, convex, or concave, bearing numerous flow-
ers, as in the Daisy. It is then called a receptacle.

Flowers are always the termination of an axis, branch,
or bough, and the order governing their arrangement is
a repetition of that which governs the ramification of the
plant.

Bracts, or floral leaves, are leaves from which the floral
axis, or the individual flowers, arise. Sometimes they
are colored and may be mistaken for parts of the corolla,
and at other times they are undeveloped. Bracts are
generally deciduous, but occasionally persist, and even
form part of the fruit, as in the cones of Firs and the
fruit of the Pine-apple. In catkins (or imperfect unisex

ENDOGENS. 135

ual sessile flowers on a spike, as in the Willow or Hazel)
the bracts are called scales. A whorl of bracts is an in-
volucre. These are sometimes adherent, as in the cup
of the Acorn. A sheathing bract inclosing one or more
flowers is a spathe. This is common among Endogens,
as in Calla, Arum, and the Palms. In Grasses the outer
scales are considered as sterile bracts, and have received
the name of glumes.

The various modes of inflorescence is a subject of
profound study with botanists, but its details are too
extensive for the design of the present work. As stated
in Chap. IV, Sec. n, the parts of the flower, as regards
their development, structure, and arrangement, may all
be referred to the leaf as a type. They begin like leaves
in cellular projections, in which fibre-vascular tissue is
ultimately formed ; they are arranged in a more or less
spiral manner, and they are often partially or entirely
changed into leaves. These facts confirm Goethe's doc-
trine that all the parts of the flower are altered leaves.

12. In the type of Endogens we meet with a great
variety of flowers, some perfectly organized, as the Lily,
and others, as the Duckweed and Bulrushes, quite in-
complete. Yet even in the more lowly forms we meet
with abundant examples of the care of a beneficent
Providence accomplishing intelligent designs by various
ways, but all indicative of Divine wisdom. In the
Branched Bur-reed (Sparganium ramosum) the branches
bear yellow balls of staminate, or barren flowers, and
green pistillate, or fertile florets. " What happens in
this case," says Dr. Lindley, " occurs also in all instances
in which the stamens are separated from the pistils in

136 SCIENCE OF LIFE.

different flowers on the same plant ; we invariably find
that the stamens are placed on the uppermost parts of
the branch above the pistils, an arrangement which is
no doubt provided to facilitate the scattering of their
pollen upon the stigmas. If they were placed below
the pistils it would be much more difficult for the pol-
len to reach the stigma, and consequently, the great
end of the creation of the stamens would be almost
frustrated. We find, however, that every thing is fore-
seen and provided for by Providence, with the same
care in these little plants as in the most exalted and
perfect of the works of nature ; and that even so appa-
rently useless and insignificant a weed as the Bur-reed
contains the most convincing evidence of the worthless-
ness of the opinions of those who, denying the existence
of the Deity, would have the world believe that living
things are the mere result of a fortuitous concourse of
atoms, attracting and repelling each other with different
degrees of force."* The recent elaborate observations
of Darwin, Sir J. Lubbock, and others, upon the fertil-
ization of plants, as the Orchids, by the visits of insects,
although sought to be explained by the principle of
11 unconscious natural selection," finds a more ready and
satisfactory explanation in the case of an ever-present
Providence, since if the colors, and honey, and structure
of the flowers are " all arranged with reference to the
visits of insects," f the structure and habits of insects
are equally adapted to the fertilization of the flowers.
From the design we infer a Designer.

*" Ladies' Botany," by Dr. J. Lindley.

f Lubbock's " Wild Flowers in Relation to Insects."

EXOGENS. 137

CHAPTER X.

EXOGENS.

In all places, then, and in all seasons,

Flowers expand their light and soul-like wings,
Teaching us, by most persuasive reasons,

How akin they are to human things.
And with childlike, credulous affection,

We behold their tender buds expand,
Emblems of our own great resurrection,

Emblems of the bright and better land.

— LONGFELLOW.

i. THE term Exogen (from exo, outward, and gennao,
to produce) is applied to those plants which produce
woody and vascular layers toward the circumference.
It is the largest class, or type, in the vegetable kingdom,
including about 7,000 genera and 70,000 species of flow-
ering plants.

External to the woody layers, and between them and
the bark, is a layer of semifluid mucilaginous matter
called Cambium. Its cells are exceedingly delicate.
New cells are continually being added, on the inner side
of the Cambium layer, to the thickness of the wood,
and on the outer side of it, to the thickness of the bark,
increasing the diameter of the axis of the plant.

At the apex of the stem, and at that of the root, the
Cambium layer is continuous with the cells which retain
the power of dividing in these localities.

The general appearance of the axis of an exogenous

plant is that of a double cone; one cone representing
12*

138

THE SCIENCE OF LIFE.

the stem, the other the root ; the growing part of both

being bathed in the cambium fluid.

In the growing stem the
terminal cells (a. Fig. 57,
A) multiply and enlarge,
while they furnish new
cells to the cambium layer.
In the root, however, the
multiplying cells are not
quite at the extremity. A
sort of cap is formed by
the growing cells, (pileor-
hiza^) and receives addi-
tions to its interior, which
push out the layers exter-
nal to them. (Fig. 57, B,
C.) Thus efficient protec-
tion is afforded to the new-

FIG. 57. — A. Mode of growth in stem. B. In - ,

root. A. a. Growing cells in stem, which ly-tormed tlSSUC.
multiply by fission, b. Cambium, elaborated
by growing cells. B. a. Growing cells in

root. b. Cells produced by growing cells. Qf the tisSUCS of 3.
c. Cap, (pileorhiza.) C. Root of duckweed,

(magnified.) «. Growing point, b. Root- ing plant may be seen in

sheath, c. Cap. d. Root. .

Fig. 58. Air passages are

both intercellular and vascular, the latter in Exogens
being dotted ducts and spiral vessels. The bark con-
tains elongated liber or bast cells, but there are no sca-
lariform vessels as in Acrogens. The chlorophyll (Chap.
VI, Sec. 2) is found chiefly in the cells immediately un-
der the epidermis. See also Figs. 15 and 16. The roots
are supplied with water containing carbonic acid, air,
and oxygen, in addition to the minerals and decompos-

crf-rif^r^ 1 a rra n cr^m (*n r

EXOGENS. 139

ing organic matter (or humus) contained in the soil.

Some plants grow without attachment to the soil, deriv-

ing all their nutriment from

the air, and are called Epi-

phytes, (epi, upon; phyton, a

plant,) from being generally

found on trees. They differ

from true parasites, since the

latter prolong their tissues into

other plants, and prey upon

them. The Orchids may illus-

trate the first, and the Dodder

and Mistletoe the latter kind.

The only structure capable of
effecting the chemical changes

FIG. 58.— Diagrammatic Section of a

necessary tO plant nutrition is Flowering Plant, showing the different
. tissues. A. Ascending axis. B. De-

the Chlorophyll, Which IS mOSt scending axis. s. Surface of soil. c. c.
. . . ,.. •. -I Appendages, d. Growing point of stem.

abundant in the leaves; hence ,.Epidermis. ././. stomata: g. Layer
the materials which supply food — ?

must be carried up to the '• m- «• pit^ sPiral vessel> and dotted

duct — all air passages, r. r. Roots.

leaves. The aSCent Of fluid t. Growing point of roots. w.Cap, (pil-

eorhiza.)

from the root to the leaves

takes place by means of two distinct forces — a pushing
force, caused by absorption by the extremities of the
rootlets, and endosmose (Chap. IV, Sec. 3) from cell to
cell; and a pulling force, produced by evaporation from
the surface of the leaves.

The appendages of the root are the rootlets, and of
the stem, the leaves. Leaves are developed from the
nodes, and the internodes (Chap. VIII, Sec. 2) become
shorter toward the summit of the stem, which ends in

140 THE SCIENCE OF LIFE.

a terminal bud. Buds are also developed in the axils of
the leaves, and some of them grow into branches, which
repeat the characters of the stem ; but others, when the
plant is fully developed, grow into stalks which support
the flowers.

In Chap. IX, Sec. II, will be found a general descrip-
tion of the flower, and in Chap. IV, Sec. n, an account
of the tissues forming the leaf. The arrangement of
leaves and branches is also a subject of biological in-
terest. The mode in which branches come off from
the nodes gives rise to various forms of trees, such as
pyramidal, spreading, or weeping. In the Italian Pop-
lar and Cypress the branches are erect, forming acute
angles with the upper part of the stem ; in the Oak and
Cedar they are spreading ; while in the Weeping Wil-
low and Birch they are pendulous from their flexibil-
ity. Leaves also are placed in a fixed order for every
species of plant, and this order may be expressed by an
arithmetical formula. The arrangement of the leaves
on the axis is called phy Hot axis, (phyllon, a leaf; taxis,
order.) Each node of the axis may give rise to a leaf,
but sometimes several nodes are approximated nearly
together, and then several leaves may be produced at
the same height on the stem. When two leaves are at
the same level, one on each side of the stem, they art-
called opposite ; when a circle of leaves is thus produced
it is called a verticil, or whorl. When a single leaf is
produced at a node, and the nodes are separated, the
leaves are alternate. The relative position of alternate
leaves varies in different plants, but is tolerably uniform
in each species. In a regularly-formed branch covered

EXOGENS. 141

with leaves, if a thread is passed from one to the other,
turning always in the same direction, a spiral is de-
scribed, and a certain number of leaves and of complete
turns occur before reaching the leaf directly above that
which began the series. This may be expressed by a
fraction, the numerator of which indicates the number
of turns, and the denominator the number of leaves in
the spiral cycle. In the Peach and Plum-tree the cycle
embraces five leaves, and the spiral goes twice around
the branch. This is expressed by the formula f . In the
Alder three leaves constitute the cycle, and the spiral
has only a single turn on the stem ; the disposition of
its leaves is represented by the fraction £.

In Exogenous plants the leaves are reticulated, and
usually articulated to the stem. The flowers are formed
upon a quinary or quaternary type ; that is, their parts
are in sets of fives or fours, instead of sets of threes, as
Endogens. The embryo has two opposite cotyledons,
or seed-lobes, which gives the term Dicotyledonous to
the type.

2. According to the natural system of De Candolle,
w-hich is usually followed, Exogens are subdivided as
follows :

i.) THALAMIFLOR^:, (Thalamus, receptacle, and flos,
flower.) Calyx and corolla present ; petals distinct, in-
serted into the receptacle ; stamens hypogynous, or
growing from below the ovary, as Ranunculus, Magno-
lia, Poppy, Violet, Geranium, etc.

2.) CALYCIFLORA. A calyx and corolla present, the
petals distinct, but the stamens are perigynous, or at-
tached to the calyx ; as Rhamnus, the Leguminose fam-

142 THE SCIENCE OF LIFE.

ily, the Rose family, the Syringa, the Passion-flower,
Cactus, etc.

3.) COROLLIFLOR^E. Calyx and corolla present ; pet-
als united, bearing the stamens ; as the Honeysuckle,
Madder, Teazel, Composite family, Heaths, etc.

4. MONOCHLAMYDE^:, (Monos, one ; chlamus, a cloak,
or covering.) Sometimes called INCOMPLET/E. Corolla
wanting ; a calyx or simple perianth present. (Even
this sometimes absent.) It is divided into two sec-
tions :

A. Angiospermce. Seeds contained in an ovary, as
Amaranth, Phytolacca, Buckwheat, Laurel, Begonia,
Nettle, Fig, and the Catkin-bearing family.

B. Gymnospermce. Seeds naked. Their woody tissue
is marked by disks, (Chap. IV. Sec. 9 ;) as the Coniferae
and Cycas family.

3. Among the INCOMPLETE Exogens, belonging to
the section of Gymnosperms, or naked-seeded Exogens,
are found the Cycas family, (CYCADACEvE,) which greatly
resemble the Palms and Tree-ferns, and the Cone-bear-
ing family, (CONIFERS,) divided into the Fir and Spruce
tribe, (Abietinea^) the Cypress tribe, (Cupressineaf) the
Yew tribe, (Taxinece, and the Joint-fir tribe, (Gnetacece^

The Coniferous plants are noble trees or evergreen
shrubs, and furnish valuable timber and other important
products, as turpentine, pitch, and resin. The Pine (Fig.
59) is one of the most perfect trees of the forest, con-
sidered in respect to its beauty and uses. " Its charac-
ter and glory," writes Mr. Ruskin, " consist in its right
doing of its hard duty, and forward climbing into those
spots of forlorn hope where it alone can bear witness of

EXOGENS.

143

the kindness of the Spirit that cutteth out rivers among
the rocks, as it covers the valleys with corn ; and there,
in its vanward place, and only there, where nothing is
withdrawn for it, nor hurt
by it, and where nothing
can take part of its honor,
nor usurp its throne, are its
strength, and fairness, and
price, and goodness in the
sight of God to be truly es-
timated."

4. Among the ANGIO-
SPERM EXOGENS, or those
of the Incomplete class
whose seeds are inclosed
in an ovary. The principal
families are the Marvel of
Peru, the Amaranth, the
Phytolacca, the Buckwheat,
the Begonia, the Laurel, the
Nutmeg, the Oleaster, the
Daphne, the Sandalwood,
the Birthwort, the Pitcher-
plant, the Rhizogen, the
Spurge, the Nettle, the
Pepper, the Walnut, and
the Catkin-bearing families.

To the Buckwheat family

(POLY GONACEyE) belong the FlG> 59--Pines, (Pznus Sylvestris)

Buckwheat, (Fagopyrum esculentum^ the Sorrel, (Rumex
Acetosa,) and Rhubarb, (Rheum palmatum) In the Lau-

144

THE SCIENCE OF LIFE.

rel family are the Laurel, Bay, Camphor, Sassafras, and
Cinnamon trees.

The Pitcher-plants (Nepenthes) are among the curiosi-
ties of the vegetable world, on account of the pitcher

formed at the end of the
leaf. This is furnished
with a lid, and contains
a limpid fluid secreted
by glands in the cavity,

I K-Wk^ ^^ and in sufficient quanti-

ty to drown flies and
other insects which fall
into it. (Fig. 60.) Since
the publication of Mr.
Darwin's " Insectivorous
Plants/' these secreting
leaves (together with
those of several other
species) have attracted
much attention, as in all
probability there is in
these arrangements provision for a true digestion, as in
the case of animals.

The Euphorbiacecz, or Spurge family, contains many
trees, shrubs, and herbs, abounding in acrid milky juice,
which is generally poisonous. Siphonia elastica is one of
the plants which supplies caoutchouc, or India-rubber.
The seeds of Croton Tiglium affords Croton oil, and those
of Ricinus communis (or Palma Christi) furnish Castor-
oil. In the root of Janipha Manihot there is much
starchy matter mingled with a volatile poison. The lat-

FIG. 60.— Pitcher-plant, (Nepenthes distil-
latorza-.)

EXOGENS. 145

ter is removed by heat or washing, and the starch is
used as Cassava bread. Tapioca and Brazilian Arrow-
root are said to be procured in this way.

In the NETTLE family are about six hundred species,
including the common Nettle, Hemp, Hop, Elm, Fig,
Mulberry, Bread-fruit, the Banyan, (Ficus indica^) etc.

The Catkin-bearing family (AMENTACE^) is the larg-
est and most important of this order, since it contains
all the most important timber trees. (Fig. 61.) The

Alder, Birch, Willow, Poplar, Oak, Chestnut, Hornbeam,
and Plane are here brought together because of the simi-
larity of their fructification. They produce flowers of one

sex only, the males of which are in catkins, in which the
13

,46 THE SCIENCE OF LIFE.

flowers have neither calyx nor corolla, but merely a sin-
gle scale. Their bark has an astringent quality from the
presence of tannin, and some, as the Willow, yield a
valuable tonic febrifuge, (Salicin^) The fruit of many
species contains starchy matter, rendering it edible by
man or animals, as the acorns of oak, mast of birch, nuts
of the hazel, etc.

5. In the order COROLLIFLORvE, or Exogens having
the petals united, and bearing the stamens, are to be
found the Mistletoe, the Honeysuckle, Peruvian bark,
Valerian, Teazel, Harebell, Lobelia, Heath, Cranberry,
Ebony, Holly, Jasmine, Olive, Asclepias, Dog-bane,
Gentian, Trumpet-flower, Phlox, Convolvulus, Borage,
Nightshade, Figwort, Labiate, Vervain, Acanthus, Prim-
rose, and Composite families.

The Honeysuckle family (CAPRIFOLIACE^E) is divided
into the true Honeysuckle tribe (Lonicerece) and the El-
der tribe, (Sambucecz?)

The Peruvian Bark family (RUBIACE^E) contains, in
addition to the Peruvian bark of commerce, (Cinchona?)
the Ipecacuanha, (Ccphaelis Ipecacuanha^) the Coffee-tree,
(Coffca arabica^) and the Madder, (Rubia tinctorial)

The Heaths (ERICACEAE) contain many beautiful and
showy plants, as the Rhododendrons, Azaleas, and Kal-
mias. The Partridge-berry, (Gaultheria procumbeus^ the
Bear-berry, (Arctostaphylos Uva-Ursi,) and the Chima-
philla, (Pyrola innbcllata^) are sometimes used in medicine.

In the Olive family (OLEACE^:) is placed the Olive,
Lilac or Syringa, and the Ash, (Fraxinus excelsior?)

The Gentians (GENTIANACE^E) are mostly dwarf her
baceous plants, with deep blue flowers.

EXOGENS. 147

The CONVOLVULACE^E, or Bind-weed family, are twin-
ing plants with showy flowers, except the tribe of Dod-
ders, (Cuscutecz,) which are leafless parasites. Here we
find the Jalap, and Scammony, and Sweet-Potato, (Bata-
tas, edulis^)

The Nightshade family (SoLANACE^) contains the
Potato, (Solanum tuberosum^) the Deadly Nightshade,
(Atropa Belladonna^ the Henbane, (Hyoscyamus niger}
the Thorn-apple, (Datura Stramonium^) Tobacco, (Nice-
tiana Tabacum^) Cayenne-pepper, (Capsicum annium,} the
Tomato, (Lycopersicum esculentum^) etc.

The LABIATE are characterized by two long and two
short stamens, four little nuts or naked seeds, and ir-
regular corollas. The plants are generally fragrant and
aromatic, and none of them are injurious. Many are
used in medicine as carminatives. Mint, Lavender,
Sage, Savory, and Balm, are examples of the family.
From Thyme a sort of camphor has been procured called
Thymol, which has similar antiseptic properties to Car-
bolic acid, but with pleasant odor.

The family COMPOSITE is a very extensive one. The
florets are arranged in involucrated heads, and the an-
thers cohere into a cylinder. It is subdivided into three
sections: I. Cynarocephalce, (from cynara, the Artichoke,)
having all the flowers tubular; the involucre, hard, con-
ical, and often spiny, as the Thistle, Burdock, etc.
2. Corymbiferce, (corymbus, a comb, and fero, to bear,)
having tubular florets in the disk (center) and ligulate in
circumference, (or ray;) involucre hemispherical, leafy, or
scaly, rarely spiny, as Feverfew, Wormwood, Tansy, Ar-
nica, and Sunflower. 3. Cichoracece, (cichorium, succory,/

148 THE SCIENCE OF LIFE.

having the florets all ligulate, as Chicory, Dandelion, and
Lettuce. The Daisies, Asters, Chrysanthemums, and
Dahlias of the gardens are all composite flowers.

6. In the subdivision of CALYCIFLORE^E are placed
Exogens which have a calyx, and corolla with distinct
petals, and whose stamens are attached to the calyx.

In the Buckthorn family (RHAMNACE^:) we find the
genus Rhamnus, several of whose species yield cathartic
medicine, and Ceanothus, or Mountain tea.

The Cashew-nut family (ANACARDIACE^:) contains the
Cashew-nut, (Pistacia vera}) Rhus Toxicodcndron, or Poi-
son-oak, and many plants which furnish varnishes, as the
Japan lacquer, (Stagmaria verniciflua^}

A number of fragrant balsamic resins, including myrrh,
(Balsamodendron Myrrha?) are obtained from plants of
the Amyris family, (AMYRIDACE^E.)

The Pea and Bean family (LEGUMINOS^:) is very ex-
tensive, containing more than four hundred and fifty
genera and six thousand five hundred species. It em-
braces many valuable medicinal plants, as those yielding
Senna, Gum-arabic, Tragacanth, Catechu, and Kino;
important dyes, as Indigo and Logwood ; valuable tim-
ber-trees, as Locust-tree and Rosewood ; and plants fur-
nishing nutritious food, as the Bean and Pea. This
order has been divided into three sub-orders, I. Papilio-
nazece ; having papilionaceous flowers, the petals imbri-
cated in aestivation, and the upper one exterior. The
plants of this section often have beautiful showy flowers,
as Robinia, Laburnum, Lupinus, etc. The various kinds
of Clover, Beans, Peas, and Pulse belong to it. The
Glycyrrhiza glabra, or plant yielding liquorice-root, the

&XOGENS. 149

Myroxylon peruiferum, or source of the Balsam of Peru,
and many other plants having medicinal qualities, are
found here. 2. Ccesalpinece. Flowers irregular, but not
papilionaceous, petals spreading, imbricated in aestiva-
tion, upper one interior. Here we find the place of sev-
eral plants used in medicine, as various species of Cassia
or Senna, the Tamarind-tree, and the Logwood, (Hcema-
toxylon?) 3. Mimosece. Flowers regular, petals valvate
(without overlapping) in aestivation ; as the different
species of Acacia, yielding Gum Arabic, and the MimostB,
or Sensitive plants.

The Rose family (ROSACE^) is also a very large one be-
longing to the Calyciflorece. Its sub-orders are, I.) Chrys-
obalancce, petals and stamens irregular, ovary stipitate,
its stalk adhering to the side of the calyx, style basilar,
fruit a i-2-celled drupe, (or fleshy fruit.) 2.) Amyg-
dalece, tube of calyx lined with a disk, styles terminal,
fruit a drupe. 3.) Spiraea, calyx-tube herbaceous, lined
with a disk, fruit of numerous follicles, seeds apterous.
4.) Quillaiece, flowers unisexual, calyx-tube herbaceous,
fruit capsular, seeds winged at the apex. 5.) Sangui-
sorbea, petals none, tube of calyx thickened and indu-
rated, stamens definite, nut solitary, inclosed in the
calycine tube. 6.) Potentillece, calyx-tube herbaceous,
lined with a disk which sometimes becomes fleshy, fruit
consisting of numerous achaenia, (small, brittle, seed-like
fruit.) 7.) Rosece, calyx-tube contracted at the mouth,
becoming fleshy, lined with a disk, and covering numer-
ous hairy achaenia. 8.) Pomece, tube of calyx more or
less globose, ovary fleshy and juicy, lined with a thin

disk, fruit a i-5-celled, or spuriously lO-celled, pomum.
13*

150 THE SCIENCE OF LIFE.

Many of the plants of this order yield edible fruits, as
Raspberries, Strawberries, Plums, Apples, Pears, Cher-
ries, Peaches, and Apricots. Plants of the sub-order
Amygdaleae are remarkable for the presence of hydro-
cyanic acid, as in the kernel of the Almond, (Amygdalns
communis^ especially the bitter Almond ; the leaves
of the Peach, (Amygdalus persica,) and of the Cherry-
laurel, (Prunus Laurocerasus.} The sub-order Pomeae
supplies Apples, Pears, and Quinces. The seeds contain
hydrocyanic acid. The other sub-orders have plants
distinguished by astringent and tonic properties, as the
root of Potentilla Tormentilla, and the petals of Rosa
gallica, the Red Rose.

FIG. 62. — A Mangrove Forest.

EXOGENS. 151

The RHIZOPHORACE^E, or Mangrove family, is named
after Rhizophora Mangle, the Mangrove, which forms
thickets at the muddy mouths of rivers in tropical
countries, and sends out adventitious roots which often
raise up the main trunk, and give the tree the appear-
ance of being supported on stalks. (Fig. 62.) The fruit
is sweet and edible.

The Myrtle family (MYRTACE^E) contains trees or
shrubs which are usually natives of warm countries.
Some of the genera are peculiar to Australia, as the
Eucalyptus, or Blue Gum-tree, which is being planted
extensively in California. It is a rapid grower, and
promises to be serviceable as a forest tree. It contains
a medicinal balsamic resin. The Pimento, (Myrtus Pi-
menta,) the Pomegranate, (Punica Granatum,) and vari-
ous species of edible Guavas and Rose-apples belong to
this order. .

The Evening Primrose (CEnothera) and the FucJisia
belong to the order ONAGRACE^E, or the Evening Prim-
rose family.

The Cucumber family (CUGURBlTACEyE) contains many
plants that are drastic purgatives, and others whose fruits
under cultivation are edible, as the Melon and the Colo-
cynth, both species of the same genus, (Cucumis.)

The Passion-flowers (PASSIFLO RACEME) received their
name from a fancied resemblance to the scenes at Cal-
vary. The superstitious monks saw in the five anthers
a resemblance to the wounds of Christ ; in the triple
style, the three nails on the cross ; in the central pillar,
the cross itself; and in the filamentous processes, the
rays of light round the Saviour, or the crown of thorns.

152 THE SCIENCE OF LIFE.

The PORTULACACE^:, or Purslane family, are chiefly
herbaceous plants, found in dry, barren situations, or on
the sea-shore. Some of them have tuberous roots which
have been proposed as substitutes for the potato, as
Claytonia tuber osa, and Melloca tuber osa. The first is a
Siberian plant, the other a native of Peru.

The Cactus family (CACTACE^E) contains many succu-
lent plants, destitute, for the most part, of leaves, the
place of which is supplied by fleshy stems of grotesque
figures. Some are angular, and grow to a height of

FIG. 63. — A Group of Cactacese.

thirty feet; others are roundish, covered with stiff spines,
and not over a few inches high. Their flowers are often
large and beautiful, varying from pure white to rich
scarlet, or purple. Some are night-flowering, as the
Cereus grandiflorus. In Mexico and Southern Califor-
nia there are a large number of species, some of which
are of gigantic size. (Fig. 63.)

EXOGENS. 153

The Gooseberry and Currant family, (GROSSULARIA-
CE.E,) the Saxifrage family, (SAXIFRAGACE.E,) the Witch-
hazel family, (HAMAMELIDACE^E,) are all of this section
of Exogens, with many others. The Umbelliferous fam-
ily (UMBELLIFERE^E) are characterized by the radiating
or umbrella-like arrangement of the florets. The prop-
erties of the plants of this family are various. Some
yield articles of diet, as the Parsnip, (Pastinaca sativa^)
Carrot, (Daucus Carota,} and Parsley, (Petroselinum
sativum.) Others yield milky juices, which dry into a
fetid gum-resin, as the Ferula Assafcetida, yielding Assa-
fcetida, and Dorema Ammoniacum, which produces Am-
moniae. Others again supply a carminative and aro-
matic oil, as Caraway-seeds (Carum Carui) and Fennel,
(F&niculum dulce.) Some species are quite poisonous,
as the Conium maculatum, or Hemlock, which contains
a volatile alkaline poison, called Conia.

7. In the sub-class, or order THALAMIFLOR^E, the
stamens are inserted under the pistil into the thalamus,
or receptacle. The petals, also, are inserted into the
receptacle. In some cases the petals are abortive, and
it becomes hard to determine whether the plant belongs
to this division or to Monochlamydeae.

The RANUNCULACE.E, or Crowfoot family, is charac-
terized chiefly by having several distinct carpels, above
numerous stamens. The plants are generally narcotic
acid poisons. The Ranunculus, Anemone, Larkspur,
Aconite, and Peony are examples.

The leaves of Aconitum Napellus, or Monkshood, are
used in medicine, as well as the rhizome of Podophyllum
peltatum, or May Apple.

154 THE SCIENCE OF LIFE.

The Poppy family (PAPAVERACE^E) differs from the last
in having the carpels united into an undivided ovary,

and in having milky or
colored juice. Opium is
the dried juice of Papavcr
somniferum, (Fig. 64,) or
Poppy, and its varieties.
The Celandine (Chelidoni-
um majus] yields an or-
ange-colored juice, which
is said to be acrid. In the
leaf of this plant may be
seen under the microscope
the movement of the sap
in the laticiferous vessels.
Sanguinaria canadensis, or
Blood-root, has emetic and
cathartic properties. The
yellow California Poppy
(Eschscholtzid) is remark-
able for the two sepals of
its calyx adhering at the
edge, and separating at
the base by the growth of

the ^Wcr SO as tO form 3.

FIG. 64.-TheOpium-Pla(/'«A,Wr somni-

ferum- sort of calyptra, or hood,

over the unexpanded petals, resembling the extinguish-
er of a candle.

MAGNOLlACEyE, the Magnolia family, contains the well-
known Magnolias, remarkable for large odoriferous flow-
ers, the Swamp Sassafras, (M. glauca^) whose bark is used

EXOGENS. 155

as a substitute for the Peruvian bark, and the Lirioden-
dron tulipifera, or Tulip-tree, etc.

The Side-saddle family (SARRACENIACE.E) contains
the genera Sarracenia and Darlingtonia, which (like Ne-
penthes) are characterized by a pitcher-like append-
age to the leaf, containing a fluid secretion, supposed
to have the power of digesting insects which fall
into it.

CRUCIFER^E, the Cruciferous, or Cress-wort family,
known so readily by their four cruciate petals, contains
a large number of plants, none of which are poisonous,
although some are stimulant and even acrid. Most of
the common culinary vegetables belong to this order, as
Cabbage, Cauliflower, Turnip, Radish, Cress, and Mus-
tard. Many garden flowers also are of this family, as
Wallflower and Alyssum.

The Violet family, (VlOLACE^,) the Mignonette family,
(RESEDACE^:,) the Berberry family, (BERBERIDACE^E,)
the Rock-Rose family, (ClSTACE^E,) the St. John's-wort
family, (HYPERICACE^E,) the Vine family, (VlTACE^E,)
the Geranium, or Crane's-bill family, (GERANIACE^E,) the
Wood-sorrel family, (OXALIDACE^E,) and many others,
must be passed by, since space forbids us to enlarge.

The Quassia family (SiMARUBACE^E) is noted for the
bitter and tonic principle contained in the wood of Quas-
sia amara, and other species.

The Rue family (RUTACE^E) is also known in medi-
cine, since it furnishes Rue, Buchu, (Barosma crenata^)
and other agents.

The Flax family (LINAGE^:) furnishes the well-known
Flax, (Linum usitatissimum^ whose inner bark yields

I56

THE SCIENCE OF LIFE.

linen and cambric. The seeds are mucilaginous and
oleaginous.

The Water-lily family (NYMPH^CE^E) contains plants
with showy flowers. (Fig. 65.) Victoria regina is one of

FIG. 65. — Common Water Lily, (Nymphcea alba.)

the largest known, the white and rosy flowers being four
feet in diameter, and the leaves fifteen feet across, ac-
cording to Schlieden.

DROSERACE^:, .the Sundew family, is remarkable for
its insectivorous properties. The Droseras are furnished
with glandular hairs, which exhibit drops of fluid in sun-
shine, hence the name.

Dioncea muscipula, Venus's Fly-trap, has the laminae of
the leaves in two halves, each furnished with three irri-
table hairs, which, on being touched, cause the folding
of the divisions in an upward direction.

The Chickweed and Pink family (CARYOPHYLLACE/E)
contains all the Carnations, or Pinks, (Dianthus^) Chick-
weed, (Stellaria media,) etc.

The Mallow family (MALVACE^) contains many whole-
some mucilaginous plants. The Mallow, (Malva^ the
Hollyhock, (Althcea rvsea,) the Abutilon, (A. esculentum^}
and the Cotton-plant, (Gossypium^) belong here. (Fig. 66.)

EXOGENS.

157

The produce of the latter plant employs the labor of a
million and a half of people in England alone, and fur-
nishes clothing to hun-
dreds of millions.

The Tea family (TERN-
STR^MIACE^E) has in it
the beautiful Camellias
of Japan, and the plants
which furnish tea, (Thea-
viridis and Bohca^ The
use of the leaves of these
plants is immense, no
less than fifty-six mill-
ions of pounds being im-
ported into Great Britain

in a single year, (1846.) FlG- 66-The Cotton-piant,
The bitter principle in tea, called theine, may be pro-
cured by adding a slight excess of acetate of lead
to a decoction of tea, filtering hot, evaporating, and
subliming.

The Orange family (AURANTlACEyE) contains about a
hundred species. The plants contain receptacles of vola-
tile oil. The fruit has an acid or subacid pulp, and the
wood is compact. The Orange, Lemon, Lime, Citron,
and Shaddock belong here.

AcERACEvE, the Maple family, contains the Maple and
Sycamore, (Acer pseudo-platanus^} The Sugar Maple
(A. saccharinum) yields a sap from which sugar is manu-
factured.

The Mahogany family (CEDREIACE^E) contains plants

with an aromatic fragrance. Swietenia Mahogoni sup-
14

158 THE SCIENCE OF LIFE.

plies the well-known mahogany wood, and Chloroxylon
Swietenia, satin wood.

8. In the rapid sketch we have made of the vegetable
kingdom, we have omitted the minute botanical details
characteristic of each family, and have only given the
principal differences and resemblances of types and
classes, with some few representative forms in the most
important families. These general peculiarities of plants
serve in a great degree to define the character of land-
scape scenery in various parts of the world. Gray and
withered Lichens clothe the barren confines of vegeta-
tion toward the snow-line of mountains or at the north,
while Mosses form a silken cushion over rock and soil
with their delicate leaflets.

Grasses are characterized by their sociability, and call
forth agreeable sensations by their soft carpet of green
and pliant leaves. The Sedges, on the contrary, with
stiff and rugged stems and leaves, rejected by cattle,
awaken no pleasing associations. In tropical climates,
as in Hindustan, the tall Bamboo sometimes overtops
the trees, and forms a meadow above the forest. There
the Plantain stem swells with sap, the leaves expand and
are split by the wind, and the great flower-bunches beam
with intense color. Between the reeds and the banana
plants the lilies may be placed. The arrow-shaped
leaves of the Aroids, with strange and often brightly-
colored spathes, mark the transition to the Orchids.

The stems as well as the leaves of plants often give
character to a landscape, as in the Heaths — low, branch-
ing, dull-green or gray shrubs, whose blossoms scarcely
obliterate the melancholy impression produced where

EXOGENS. 159

they abound. The arborescent Heaths (Casuarina] form
many of the gloomy woods of Australia. Still more
striking are the forms of the thorny Cactuses, (Fig. 63,)
consisting merely of fleshy stems and branches of singu-
lar shapes. The Yuccas of Mexico, the great African
Aloes, and the Grass-trees of Australia, with their solid
liliaceous leaves, of a dull green, afford a picture of im-
movable repose. The stiff, shining leaves of Pandanus,
or Screw Pine, arranged in spiral lines, contrast greatly
in the Sandwich Islands with the finely divided leaves
of the Fern, spreading in graceful elegance, and trem-
bling in the breeze. Between these two extremes is the
Palm-form, which gives most characteristic beauty to the
tropical world. Some Palms have feathered leaves,
others have fan-leaves, and in some of the umbrella
Palms the crown consists of a few fans elevated on long,
slender stalks. In all the inflorescence breaks from the
stem below the origin of the leaves, and the sheath
hangs down, often several feet long. The shape and
color of the fruit varies from the large triangular Cocoa-
nut to the berry of the Date. The aerial summits of
the Palms, projecting like a colonnade above the thicket,
and crowned with leaves, give them an air of beautiful
majesty. (Fig. 51.) Deciduous, or Leafy woods, (Fig.
61,) with their branching stems and broad foliage, form
dense, compact, vegetable masses, characteristic of tem-
perate climes. Wand-like forms, with narrow, fluttering
leaves, often covered with silvery down on the under
side, are represented by the Willow and Poplar, and in
the south of Europe by the Olive. The Conifers, or
Needle-leaved woods, are distinguished by their narrow,

160 THE SCIENCE OF LIFE.

dark-green leaves and whorl-like branches. (Fig. 59.)
In the tropical or equinoctial regions the mass of leafy
woods is marked by the prevalence of the Mallow-form,
with long-stalked and palmately-lobed leaves. The
giant Baobab, the barrel-like trunk of the Bombax, and
the purple-blossomed Hibiscus bush belong to this class.
The Australian Laurels and Myrtles are allied to the
northern Willows, yet their rigid leaves, shining as if
varnished, or covered with a silvery felt which mingles
with the shining green, give them a characteristic phys-
iognomy.

Thus even a general observer may notice variety
enough to indicate that a free intelligence has arranged
these forms to minister mental enjoyment, as well as to
supply the needs of intelligent creatures. Archbishop
Trench has well said that the characters of nature which
every-where meet the eye " are not a common, but a sa-
cred writing — they are hieroglyphics of God."

PROTOZOA. 161

CHAPTER XI.

PROTOZOA.

Since all bioplasm possesses certain common characters, and the bio-
plasm of one plant or animal produces formed matter of a very different
kind from that resulting from another portion of bioplasm, we must ad-
mit that in nature there are different kinds of bioplasm. — DR. BEALE'S
Bioplasm.

I. IN studying the structure of the Protozoa, or primi-
tive animals, we seem to be going backward, since each
is composed of a single mass of bioplasm, like the sim-
plest vegetables, or Protophytes. Although similar in
structure, the Protozoa and the Protophytes are biolog-
ically distinct in function, since the latter generally de-
compose Carbonic acid under the influence of light, and
generate Chlorophyll and albuminous compounds in a
manner similar to the leaf-cells of the most perfect
plant, while the Protozoa ingest and digest both animal
and vegetable food as effectively as the most complex
animals.

We have already seen (Chap. II, Sec. 7) that all living
matter, or bioplasm, has essentially spontaneous motion,
nutrition, growth, and reproduction. We cannot con-
ceive, therefore, of any form of life, either vegetable or
animal, without these characteristics. The simplest and
most embryonic structures in both kingdoms of nature
exhibit these functions. Whether spontaneous motion
is proof of consciousness and will, will be considered

hereafter.
H*

162 THE SCIENCE OF LIFE.

2. The MONERA of Prof. Haeckel, if the group shall be
accepted by naturalists, will include the simplest proto-
zoans, cr those in which the entire living body is a mere
particle of bioplasm, without nucleus, vacuole, invest-
ment, or other structure, yet capable of bioplasmic mo-
tions and other functions. Bathybius, referred to in
Chap. IV, Sec. 3, was supposed to be of this class.

3. The GREGARINID^: are parasitic. Each consists 01
a single cell, which passes through changes similar in
many respects to Protophytes. It becomes globular and
encysted in a horny envelope, and the inclosed bioplasm
breaks up into particles which become " pseudo-navicel-
lae," or forms similar to the Navicula of the family Dia-
tomaceae. It is not unlikely that the Gregarince are but
phases in the life-history of other parasitic worms.

4. RHIZOPODA. The Rhizopods, or root-footed Pro-
tozoans, (rhiza, a root, and pous, foot,) are characterized
by the power of spontaneously throwing out delicate
processes of their bioplasm, called pseudopodia, or false
feet, for prehension or locomotion. They have no cilia.
Dr. Carpenter has divided the class into three orders :
I. Reticularia, whose bodies are indefinite extensions oi
viscid bioplasm, freely branching and subdividing into
fine threads, but readily coalescing when they come into
contact. 2. Radiolaria, whose bioplasm has an invest-
ing membrane of formed material which prevents the
coalescence of the radiating or rod-like extensions of
the pseudopodia. 3. Lobosa, whose bioplasm has an in-
vesting membrane, or ectosarc, and whose false feet are
lobose extensions of the body itself.

In the first order, that of reticularian rhizopods, we

PROTOZOA. 163

find many genera and species which secrete a shell or
external envelope of Carbonate of Lime, or Chalk.
These shells are often of singular beauty. They are
generally perforated by a large number of minute open-
ings for the passage of the pseudopodia, and hence are
termed Foraminifera, {foramen, an aperture ; fero, I
carry.) (Fig. 67.) Some of these foraminifera are sin-
gle chambers, often like striated flasks, (La gen a >) but

FlG. 67. — Rosalina ornata, with its pseudopodia extended.

others are compound, either straight, (Nodosaria,) spiral,
(Rotalia,) or irregular, (Globigerina.) These shells are
generally microscopic, although some, as the Nummu-
lites, may be an inch in diameter, and the fossil Eozoon
Canadense, which is referred to this order, was of indefi-
nite size. The Foraminifera accumulate in the bed of
the ocean in great numbers, yet in former ages they
were still more prolific, since the Chalk cliffs of England.

164

THE SCIENCE OF LIFE.

the building-stone of Paris, and the limestone of the
Egyptian pyramids, are composed of their remains.

In the Radiola-
rian order is placed
the ActinopJiryssol,
(Sun-Animalcule,)
( Fig. 68 ;) many spe-
cies of Polycystina,
which secrete sili-
cious shells, of va-
rious shapes and of
wonderful beauty,
(Fig. 69 ;) and col-
onies of gelatinous

FIG. 68— Acrhophrys sol, in different states. A. In rllizopods, (TJlCllaS-
its ordinary sunlike form, with a prominent contractile
vesicle, o. B. In the act of division or of conjugation,
with two contractile vesicles, o, o. C. In the act of feeding. * *•»/-«•
D. In the act of discharging faecal (?) matters, a and b. »

ule's.
A

To the order Lobo-
sa belongs the Amaba
princeps, (Fig. 2,) to
which reference has
been so often made,
since it has occupied
so important a posi-
tion in modern biolo-
gy. Chap. II, Sees. 2,

3,5-

5. INFUSORIA, or An-
imalcules. The term

FIG. 69. — A. Podocyrtis Schomburgkii. B. Rhopa- r . i • j

locanium ornatum. InfuSOHa IS applied tO

PROTOZOA. 165

this class because the species abound in any infusion
of vegetable or even animal matter which is allowed
to putrefy. The word was formerly applied to a much
larger number of species than now, since many forms
once considered animal have been placed in the vegeta-
ble kingdom, as the Desmids, the Diatoms, the Volvox,
and many other Protophytes. The Rotifers, or wheel-
animalcules, also, on account of their organization, are
referred to the articulate type of animal life. It is pos-
sible that some of the Infusoria may be but larval forms
of higher animals. After all this pruning, however, the
class is still a large one, and full of interest. It is divided
into three orders : Ciliata, Suctoria^ and Flagellata.

Ciliated Infusoria (ciliatd) are most numerous, and are
named from the cilia, or hair-like organs, round the
mouth, or body, of the animalcule. Cilia are not con-
fined to animalcules. They are found among Proto-
phytes, (Chap. VI, Sec. 3.) They also exist in many
organs of the higher animals, as in the respiratory pas-
sages even of man himself. They appear to be tapering
prolongations of bioplasm, or of formed material in con-
nection with bioplasm, and have a sort of waving or
circular motion. In the internal organs of man their
actions are constant, entirely without consciousness, and
may continue long after the death of the body. In the
animalcules the ciliary action is interrupted and renewed
in such a way as to impress an observer with the idea of
choice and direction.

Vorticella, or the bell-shaped animalcule, was described
in Chap. I, Sec. 6, and the life-history there given may
serve for a representation of the entire order.

166 THE SCIENCE OF LIFE.

Epistylis differs from Vorticella in having a branching
and non-contractile stem.

Vaginicola possesses a horny, cuticular case, (a cara-
pace, or lorica,} into which the animal can retire.

Stentor is a fresh-water infusorian, shaped like a trum-
pet. It may be found either free or attached.

Paramecium, (Fig. 70,) is a free, fresh-water animal-

FIG. 70. — Paramecium Aurelia, an Infusorian animalcule, magnified 300 times,

cule, shaped like a slippe~r, the hole for the foot being
represented by the mouth.

Suctorial Infusoria (order Suctoria] may be illustrated
by the parasitic Acineta, Chap. I, Sec. 6. They have
filaments ending in suctorial disks, which are capable
of protrusion and retraction, and are used for pre-
hension.

The Flagellate Infusoria (order Flagellata) perform lo-
comotion by means of long filaments, or flagellae, which
may be single, double, or multiple.

The Noctiluca, (Fig. 71,) is the best-known member
of this order. It is very minute, about one eightieth of
an inch in diameter, and presents little more structure
under the microscope than a simple sac of bioplasm,
with vacuoles, an oral aperture, and a tail of flagellum,

PROTOZOA. 167

but at night these tiny beings light up the ocean with
myriads of lamps, whose phosphorescent property is
yet a profound mystery.

The Cercomonady an animal-
cule, with a long flagellum at
each end, is noted for the thor-
ough investigations made by
Messrs. Dollinger and Drysdale.
These gentlemen found it would
increase for several days by fis-

9 FIG. 71. — Noctiluca miliaris.

sion. Then it would lose the

flagellae and assume an amoeboid form. Two of these
amoebiform Cercomonads would conjugate and become
encysted, and the rupture of the cyst gives exit to mi-
nute germs, which grow into the original parent form.
A temperature of 150° F. sufficed to destroy the adult
forms, but at 300° F. the germs still lived and devel-
oped. This latter fact makes strongly against the theory
of spontaneous generation.

6. SPONGES, (Spongida.) What we familiarly call a
sponge is but the skeleton of a colony of Protozoa. In
this class a number of bioplasts, whose individuality is
still almost if not complete, are united together, sup-
ported on a skeleton of horny, silicious, or calcareous
fibers united so as to form a net-work of tubes.

In a living sponge currents of fluid set in through
minute pores on the surface, and come out in large
streams through the larger apertures, (oscula^) These
currents are kept up by the cilia connected with the bio-
plasmic masses which line the canals and cover the
skeleton. By means of these currents particles of food

1 68

THE SCIENCE OF LIFE.

are brought within reach of the bioplasts. (Fig. 72.)
The Sponges are divided into three orders : Horny,

FIG. 72. — Sponge in action.

Silicious, and Calcareous sponges. In the first order
(Keratosa) is found the sponge of commerce, which owes
its value to the fineness of its fibers and the absence of
silicious spicules. Some sponges of this order have

YIG. 73.. — a. Portion of Halichondria (?) from Madagascar, with spicules projecting
from the fibrous network, b. Silicious Spicules of Pachymatisma.

•flinty spiculse of various shapes, as pins, clubs, crosses,
hooks, and anchors. (Fig. 73.) The silicious sponges

PROTOZOA. 169

(Silicea) sometimes have their spicules woven or fused
together, as in the beautiful Euplectella, or Venus's
Flower-basket. In Hyalonema, the glass-rope, the long
spicules, are twisted together.

In the order Calcarea the skeleton is composed of Car-
bonate of lime. Except a few fresh-water species, as
Spongilla, sponges are marine. The best sponges of
commerce are from the Mediterranean.

7. The colonies of bioplasts in Thalassicollida and in
Sponges are analogous to the higher types of animal life,
yet the individual cells are so loosely bound together,
and so capable of living and performing all their func-
tions apart, that they are ranked as Protozoa, as the col-
onies of Volvocineae, Nostochaceae, and Confervaceae, are
placed among the Protophytes.

8. The essential difference in the vital powers of dif-
ferent classes of living things, and of the individuals of
each class, is well exhibited in the following passage from
Johnston's " British Sponges :" 4< For example, it is very
common to find growing on the same rock, or sea-weed,
a silicious, a calcareous, and a horny sponge ; they have
all the same exposure, and are all recipients of the same
nutriment, yet does each act upon this differently. One
extracts from the fluid silica, which it causes to assume
a solid crystalline form ; another selects in the same
manner the calcareous particles, which, obedient to the
laws of life, assume figures novel to them in their min-
eral state ; and again, another rejects both the lime and

the flint as injurious to its constitution."
15

170 THE SCIENCE OF LIFE.

CHAPTER XII.

RADIATA.

If we are astonished that so great deeds should proceed from the little
and low, it is because we fail to appreciate that little things, even the least
of living or physical existences in nature, are, under God, expressions
throughout of comprehensive laws, laws that govern alike the small and
the great. — DANA, Corals and Coral Makers.

1. IN the simple Protophytes and Protozoa we find the
essential structure to be a single cell, or mass, of bio-
plasm, having in one vegetable and in the other animal
characteristics. In some instances there is a colony, or
association, of bioplasts, with certain mutual relations ;
but as each bioplast is but loosely connected with the
others, and is capable of living and performing all its
functions while in a state of independence, these colo-
nies are conveniently considered among primordial types.
In the higher forms of life, either animal or vegetable,
each individual is composed of many bioplasts, derived
by subdivision of the primitive mass. With the division
of the structure there is also a differentiation of function,
so that no bioplasts of the structure, save those which
are appropriated to reproduction, can normally pursue
an independent existence.

2. The Radiate type of animal life is characterized by
the idea expressed in the word radiation. " In Radiates
we have no prominent bilateral symmetry, such as ex-
ists in all other animals, but an all-sided symmetry, in

RADIATA. 171

which there is no right and left, no anterior and poste-
rior extremity, no above and below. It is true that in
some of them there are indications of that bilateral sym-
metry which becomes a law in the higher animals ; but
whenever such a tendency is perceptible in the Radiates
it is subordinate to the typical plan on which the whole
group is founded." *

3. Radiate animals are subdivided into I. CcELEN-
TERATA, or Ccelenterates, (koilos, hollow ; enteron, intes-
tine,) or animals with an alimentary canal communicating
with the general cavity of the body ; and, II. ECHINO-
DERMATA, (echinos, a spine ; derma, skin,) or spiny-
skinned animals. Other characteristics, however, besides
those signified in the names of these sub-types are nec-
essary to. be considered.

4. The CCELENTERATA are radiate animals with a dis-
tinct body-cavity, whose walls consist of two layers of
cellular tissue, an outer (ectoderm) and inner, (endodenn,)
and contain nettling thread-cells, or small sacs full of
fluid connected with barbed filaments, capable of being
projected for stinging purposes. Most of these animals
have hollow tentacles round the mouth. There are two
large classes of Ccelenterates : I. The HYDROZOA, which
have no digestive cavity separate from the rest of the
mass which forms the body, and whose reproductive or-
gans are external ; and, II. ACTINOZOA, which have a
digestive canal distinct from the rest of the body, sus-
pended by radiating partitions, called mesenteries ; and
whose organs of reproduction are internal, placed on the
mesenteries. The first of these classes may be repre-

* Agassiz.

1/2

THE SCIENCE OF LIFE.

sented by the Hydra, and the latter by the Sea-anem-
one, or Actinia.

The Hydra is named after a fabled monster that re-
produced its heads as fast as they were cut off. The

genus comprises two species,
the green and the brown
Hydra, (H. viridis and H.
fusca.) (Fig. 74.) They are
minute creatures, about a
quarter of an inch long, gen-
erally found on the under
surface of aquatic plants, at-
tached by a disk, while their
long tentacles float down-
ward in search of prey. The
body is a simple tube, or
cavity, and the tentacles
are supplied with " lasso-
threads," or nettling thread-
cells. In the early summer
small buds grow from the
base of the body, which grow
into the likeness of the par-
FIG. 74.-Hydra fusca, with a young bud ent, and then are detached.

at b. and a more advanced bud at c. o . , /»

Sometimes a second crop 01

buds arise from the first before it is separated. Later in
the season eggs form from modified cells of the inner
layer, which burst through the outer layer, become free,
and develop into new Hydrae.

These animals are nearly allied to the Protozoa, since
the differentiation of function in the bioplasts is incom-

RADIATA. 173

plete. Hence the wonderful powers of propagation in
these creatures, which have astonished naturalists ever
since Trembley first discovered them, in 1744. He says :
" I have opened a polyp on my hand, extended it, and
cut the simple skin of which it is formed in every direc-
tion ; I have reduced it to little pieces, and, in a man-
ner, minced it. These little pieces of skin, both those
which did and those which did not possess arms, became
perfect polyps." Many curious multiple forms have
been ' produced by experiments on these animals. By
slitting the body into two branches, and these branches
again into others, a tree-like form may be produced, each
branch giving rise to a distinct head and tentacles. Or
one may be turned inside out like a glove, so that the
outer skin becomes the lining of the stomach-cavity, with
a transposition of the functions of each.

Order I. Hydroida. This order is composed of ani-
mals built on the pattern of the Hydra, just described.
They are either single, as the Hydra, or compound. The
latter are subdivided into the three families of Campanu-
larians, Sertularians, and Tubularians. They are grouped
in clusters or colonies on a common axis or stalk, (cceno-
sarc^) Each hydra-like organism is called a polypite.
New polypites arise as outgrowths from the common
stem of the colony, so that the stomach of each is con-
tinuous with the tubular center of the stalk, producing a
community of nutrition in the colony. In Chap. III.,
Sec. 14, reference was made to the alternation of genera-
tions which this order of animals so strikingly illustrates.
This process in the life-history of the Hydroids is briefly

as follows : The Polyp, a fixed animal, increases for
15*

THE SCIENCE OF LIFE.

awhile by budding, but at a certain period gives birth
by subdivision, to free swimming Medusae, or Jelly-fish
Each of these, after pursuing for a time its own course
of life and development, produces eggs which change
into ciliated bodies (Planuld) similar to some of the In-
fusoria. After a while each of these becomes stationary,
fixes itself to some weed or rock, and becomes a polyp,
or Hydroid.

Those Medusae which swim by the contraction of their
umbrella-like disk were formerly called Pulmogrades ;
those which swim by vibratile cilia attached to arms,
Ciliogrades ; those which float by an expansive bladder,
Physogrades ; and those furnished with arms, or cirri,
Cirrigrades. Another classification divided them into
" naked-eyed " and " hidden-eyed " Medusae. Since
more thorough research has shown their relation to the
Hydroids, the Medusae have been considered in reference
to the families of Hydroids from which they springe

The Tubularian family (tubulus, a little tube) consist
of Hydroids, sometimes simple, but generally compound,
united by a common trunk or coenosarc, which has an
external horny coat, or polypary. Sometimes the tube
is jointed with the tentacles placed in a whorl round each
joint, (Tubularida divisa^} sometimes it is undivided,
(71 indivisa^} Sometimes the polypary is much branched,
(as in Eudendrium?) but in the majority it is not branched.
A few species have no hard polypary, (as Corymorpha
nutans^) but simply a white fleshy stem. The polyps of
this family have no protecting cups. The Medusae bud
from the stem.

The Sertularian family (Sertula, a little wreath) is gen-

RADIATA.

175

erally regarded as a sea-weed by sea-side visitors, but a

very cursory examination with a pocket lens will suffice

to show the horny and branched polypary, with its little

cups, (Itydrothecce?)

which contain and

protect the poly-

pites. In some of

the Sertularians

the Medusae wither

on the stock, never

becoming free.

The Campanula-
rian family (Cam-
panula, a little bell)
resemble Sertula-
rians, except that
the cups (Jtydro-
thecce) are stalked
and terminal in-
stead of being lat-
eral and sessile, as
in the latter. The
reproductive caly-
ces, or ovarian cap-
sules, may contain

many Medusae FIG. 75.-Campanularia gelatinosa :— A. Upper part of
L j i i , the stem and branches, of the natural size. B. A small

evelOped portion enlarged, showing the structure of the animal.
One below the Oth- a' Terminal branch bearing polyps, b. Polyp bud par-
tially developed, c. Horny cell, containing the expanded

er, which are Set P°lyPi ^. e- Ovarian capsule, containing medusiform
gemmae in various stages of development, f. Fleshy sub-
free by the bursting stance extending through the stem and branches, and con-
11 /• necting the different polyp-cells and ovarian capsules.

O* the Cell. (P Ig. 75 •) £• Annular constrictions at the base of the branches.

176 THE SCIENCE OF LIFE.

The ordinary Jelly-fish (Medusa, or Acalepli] is soft,
gelatinous, and bell-shaped, with tubes radiating from

center to circumfer-
ence, where they con-
nect with a circular
canal. The margin is
fringed with stinging
tentacles. The radi-
ating parts are in mul-
tiples of four. These
gelatinous bells, vary-
ing from the size of a
pea to a foot or more
in diameter, float,

FIG. 76. — Development of Snrsia. i. Polyps de-
scribed as Syncoryne, natural size. 2. A polyp, mOUth downward, ill
magniried. a. Polyp stem. b. c. d. e. Medusoid n .
buds, in various stages. /. Tentacles of the polyp, the SCa, and propel

themselves by flap-
ping their sides. (Fig. 76.) There are two representa-
tive forms of Medusae, the Lucernaria, or Umbrella-aca-
leph, attached by a short pedicle, and having tentacles
disposed in eight groups around the margin, and not less
than eight radiating canals ; and Discophora, the ordi-
nary Jelly-fish, free and oceanic, with four radiating
canals in the disk, which ramify and open into a circular
canal around the mouth of the disk.

Order 2. Siphonophora, or floating Hydroids, (siphon,
a curved tube, and phero, to bear,) are free swimming or
compound floating Hydroids, with an unbranched, or
slightly branched, but muscular ccenosarc. The com-
mon stem of these colonies swims by means of enlarged
and altered polyphites, whose stomachs are undeveloped

RADIATA.

177

and whose bodies are dilated. Some possess, also, a sac
filled with air, which acts as a float, as the Physalia,
(physa, a bubble,) or Portuguese
Man-of-war, whose purple-crest-
ed air-sac and long tentacles at-
tract such attention in tropical
seas, and whose thread-cells in-
flict such painful stings when
grasped by an incautious hand.
(Fig. 77.) The Porpita {porpc,
the ring of a shield) possesses
an internal skeleton, or flat
plate, of cartilaginous texture,
which is cellular and lighter than
water. Its lower surface con-
tains a beautiful fringe of blue
tentacles, or cirri. In the Vel-
ella (velella, a little sail) a second FlG> 77'-physalia'

cartilaginous plate rises nearly at right angles from the
upper surface of the horizontal one, serving as a sail to
waft the little mariner from place to place.

CLASS II. AcTINOZOA, (actin, a ray; zoon, an animal.)
This class embraces the Sea-anemones, the Corals, and
the Ctenophora, (kteis, a comb ; phero, I bear,) or comb-
bearing Medusae. The digestive cavity is suspended in
the body cavity, like a small bag within a larger one, by
vertical partitions, some of which extend from the body-
wall to the digestive sac, but others fall short of it.
Upon these septa, or mesenteries, are the organs of re-
production. The ectoderm is more highly developed
.than in Hydrozoa, and both mesenteries and body-walls

i;8 THE SCIENCE OF LIFE.

are supplied with distinct sets of muscles. Cilia are
present on the digestive tube, producing a current both
respiratory and circulatory.

The Actinia, or Sea-anemones, are the much-admired
forms so often seen in the rock-pools around our shores,
sometimes called animal flowers, attached to the rocks
by a flat disk, expanding their petal-like tentacles in
search of prey, and, when uncovered by the retreating
tide, contracting into small round gelatinous masses.

A B

FIG. 78. — A. Sea-anemone, seen from above. B. Section of Sea-anemone, a. Cavity
of stomach, b. Surrounding chambers.

The tentacles and partitions of the body are in multi-
ples of six. Fig. 78 represents the internal form of
Actinia.

The Coral polyps are Actinozoa, which secrete coral,
generally composed of carbonate of lime, but it is occa-
sionally horny, or a mixture of horny and calcareous
matter. These polyps are usually found in colonies
formed by a continuous process of budding. The com-
pound mass is like a sheet of animal matter, fed and
nourished by numerous mouths and many stomachs.
Corals are of two kinds, the sclerobasic and sclerodermic
corals. The polyps of the latter resemble Actiniae in
structure. The earthy matter is secreted between each

RADIATA.

179

pair of partitions, so that the skeleton ot a single
polyp (or corallite) is a short tube with vertical septa

FIG. 79. — Corals.

radiating toward the center. The Fungia, or Mush-
room coral, is disk-
shaped, and differs
from others in not
being either fixed or
compound. It is sim-
ply the skeleton of a
single polyp, showing
a radiating secretion
of calcareous septa.
The various kinds of
budding in compound
coral-polyps give ris-
to a variety of shapes,
either dome -like or FIG. 8o,-Madrepore.

i8o THE SCIENCE OF LIFE.

branching. Astrcea is a hemispherical mass covered with
large cells. Meandrina, or " Brain-coral," has the mouths
of the polyps opening into each other, forming furrows.
(Fig. 79.) Madrepore branches, like a tree, with pointed
extremities. (Fig. 80.)

Sclerobasic corals are those which secrete coral by the
outer layer of the inverted ectoderm. Most of these
are of the order Alcyonaria, whose polyps are character-
ized by primate or fringed tentacles in multiples of four,
while the sclerodermic corals generally belong to the
order Zoantharia, with polyps having simple tentacles in
multiples of five or six. The characters of Alcyonarian
polyps may be seen by placing in sea-water some of
those large yellowish, gristly masses, sometimes cast up
by the sea, known as " dead men's fingers." From the

FIG. 81.— i. Sea-fan. 2. Sea-pen.

surface of each pore the tentacles round the mouth of
the polyps will protrude, showing their general resem-

RADIATA. 181

blance to Actinia. Minute spicules of calcareous matter
are scattered throughout the mass. In Gorgonia such
spicules, with horny matter, make up a continuous
branching coral in the same plane, whose ramifications
unite in a beautiful net- work. (Fig. 81.) In Corallium
rubrum, the precious coral of commerce, the axis is of
stony hardness, and branching like a shrub. In the

FIG. 82.— Red Coral.

FIG. 83.— Tubicora Musica.— Organ-pipe Coral.

living state the branches are covered with a red cceno-
sarc, (common flesh,) studded with polyps. (Fig. 82.)
The feather-shaped sea-pens (Pennatula] have the ex-
tremities of their stems buried in sand. In some genera,
as, Virgularia, the stem is prolonged to between three
and four feet in length, while the polypiferous lobes are
comparatively short. The red organ-pipe coral of the
Indian Ocean, (Fig. 83,) with its table-like partitions and

green polyps, belong also to this group.
16

182

THE SCIENCE OF LIFE.

The work of the reef-building polyps is extremely
interesting. They will not live in water whose mean
temperature is below 68° F., nor at a greater depth than
twenty fathoms, yet coral reefs are constantly found
which are several hundred fathoms thick. This appar-
ent paradox is due to the fact that the land where coral
reefs are forming is constantly subsiding, and fresh living
corals are taking the place of the dead ones. If the
center of a reef sinks more quickly than the sides a
lagoon is left, surrounded by a circular reef of coral,
called an atoll ; if an island rises in the middle of this
lagoon a barrier reef is said to be formed, (Fig. 84;)
while if the sea clearly intervenes between the reef and

FIG. 84.— A Coral Island.

the mainland, we have what is termed a " fringing ree*"."
Different species of polyps build these reefs. Madre-

RADIATA.

•83

pores, Millepores, and Gorgonidae work chiefly at the
top, next below we meet with Meandrinas, and lowest
of all, with Astraeans.

The Ctenophorce, or comb-bearing Medusae, exhibit
traces of a nervous system in a ganglionic mass at the
upper end, or pole, of the animal, with nervous filaments
radiating to every part of the body. They are trans-
parent gelatinous animals, which swim freely by means
of bands of comb-like fringes or paddles. Their internal
structure is quite complex, having a distinct alimentary
canal, and ducts for the circulation of fluid. They are
retained in the Radiate type, on account of the radiate
arrangement of the bands of cilia and the presence of
urticating organs on the tentacles, although their affini-
ties would seem to place them elsewhere.

The Beroe and Cydippe (Fig. 85) and Cestum Veneris,

FIG. 85. — A. Cydippe pileus, with its tentacles extended. B. Beroe Forskalii, showing
the tubular prolongations of the stomach.

or Girdle of Venus, belong to this order. In the latter,
the sides are prolonged into a ribbon, although the
mouth and digestive organs are confined to the middle

1 84 THE SCIENCE OF LIFE.

of the body. In the day-time its waving cilia along the
margins of the body glitter with the tints of the rainbow,
and at night it appears like a long waving flame in the
water.

5. The subtype of Radiate animals, called ECHINO-
DERMATA, is distinguished by the possession of a nervous
system, in the form of a pentagonal ring round the
mouth ; an alimentary canal, with oral and anal aper-
tures ; a peculiar system of circular and radiating canals ;
and a symmetrical arrangement of all the parts of the
body around a central axis, in multiples of five. Some
star-fishes (Solaster) have twelve rays. In all Echino-
derms, probably, sea-water is freely admitted into the
body-cavity around the viscera. The canals likewise
contain water, which enters through a porous tubercle,
the madreporic plate, or dorsal wart, best seen on the
back of the star-fish and the sea-urchin. Some natural-
ists rank Echinoderms as Worms.

The Crinoidea, or Sea-lilies, so called from their re-
semblance to flowers, are fixed to the sea-bottom by a
hollow, jointed, flexible stem, which carries the body,
which is cup-shaped, with radiating arms, or tentacles.
This order includes an immense number of fossil forms,
but deep-sea dredging has brought up many living
species, formerly thought to belong exclusively to the
Mesozoic period. They all possess an internal skeleton
of infiltrated calcareous matter, so that the entire animal
consisted of thousands of stellate pieces, or joints, con-
nected by animal matter. As each joint is furnished
with at least two bundles of muscular fiber, one for ex-
tension and one for contraction, Dr. Carpenter esti-

R ADI ATA. 185

mates three hundred thousand such muscles in a single
Pentacrinus — an amount of muscular apparatus far ex-
ceeding any that has been elsewhere observed in the
animal creation. The family, COMATULlDyE, or Hair-
stars — sometimes termed Feather-stars — in their young
condition, resemble the Encrinites, or Sea- lilies, being
supported on a long flexible stalk, composed of calcare-
ous cylinders. At maturity they quit their attachment,
and crawl about like other Star-fishes.

The order ASTEROIDEA, or Star-fishes, consists of ani-
mals with a flat central disk, having five or more arms,
or lobes, radiating from it, and containing branches of
the viscera. The skin is leathery, hardened by small
calcareous plates, (eleven thousand or more,) but some-
what flexible. The mouth is below, and the rays are
furrowed underneath and pierced with numerous holes
through which pass sucker-like tentacles for locomotion
and prehension. These furrows are named ambulacra,
or avenues, from a fancied resemblance to a walk, or
alley, in a garden. As the tentacles, or suckers, are only
protruded from these spaces, they also have been called
ambulacra. The arrangement for their protrusion will
be described in connection with the Sea-urchins, as well
as the Pedicellaria (formerly believed to be parasitic or-
ganisms) found near the mouth.

About one hundred and fifty species of Star-fishes are
known, divided into three groups: (i.) those having four
rows of feet, as the common five-fingered Star-fish, or
Asterias ; (2.) those with two rows, as the many-rayed
Solaster, or Sun-fish, and the pentagonal Goniaster ;

(3.) those with long slender arms, which are not prolon-
16*

1 86 THE SCIENCE OF LIFE.

gations of the body, and are not provided with suckers,
as the Ophiura, or Brittle-star, (Fig. 86,) and Asterophy-

ton, or Basket-fish. The last
group are inferior in struct-
ure, and resemble inverted
stemless Crinoids. The di-
gestive sac is confined to the
disk, and the madreporic
plate is underneath.

The order ECHINOIDEA,
FIG. se.-Ophiura. Or Sea-urchins, contains those

Echinoderms whose skin secretes calcareous plates, form-
ing a hollow shell, covered with spines, and varying in
shape from a sphere to a disk. The shell of an Echinus
is made up of twenty rows, or zones, of plates, of which
five pairs are ambulacral, pierced with minute pores for
the protrusion of ambulacra, or sucker-feet, and five pairs
alternating with the former are inter-ambulacral. The
shell is developed from a membrane which lines the in-
terior of the plates, and passes between the joints, so
that additions can be made to their edges, by which
means the shell grows and preserves the same relative
proportions. The upper end of the shell, in addition to
five small circularly disposed plates, carries five large
genital plates. Each of these has a duct for the passage
of ova or spermatazoa, and an ocellus, or eye-spot. One
of these plates is the madreporic tubercle, with minute
apertures communicating with the madreporic canal.
Locomotion is effected by the hollow muscular feet,
each of which communicates with a water sac ; they
also communicate with each other, so that as each

RADIATA.

sac contracts, water is forced into the corresponding tube,
which is thereby elongated and protruded. (Fig. 87.)

1

FIG. 87. — Morphology of Echinoidea. i. Echmid larva, a. Mouth, b. Stomach, c. In-
testine, s. Skeleton. 2. Diagram of Echinus. The spines and the ambulacra are repre-
sented over a small portion of the test ; the vascular system is cross-shaded ; the nervous
system is represented by the black line. a. Anus. b. Stomach, c. Mouth. da.nAf. Vas-
cular rings round the alimentary canal, e. Heart, g. Test. k. Nervous ring round the
gullet, i. Ambulacral ring, or circular canal round the gullet, k k. Polian vesicles. /. Sand
canal, m m. Radiating ambulacral canal. ». Secondary ambulacral vesicles, o. Ambu-
lacra, or " tube-feet." p. Spines, r. Madreporiform tubercle.

The shell of the
Echinus is cov-
ered with semi-
globular warts,
or beads, each
of which during
life supports a
sculptured spine
with a hollow at
its base, forming

FIG. 88. — Shell of Echinus, or Sea-urchin ; on the right side,
and ligaments a covered with spines ; on the left, the spines removed.

ball and socket joint, subsidiary to locomotion. (Figs.
88 and 89.) Pedicellarice are minute, almost microscopic,

88

THE SCIENCE OF LIFE.

jointed spines, scattered all over the shell of the Echinus,
and terminated by a three- fold claw, capable of being

FIG. 89. — Morphology of Echinoidea. i. Portion of the test of Galerites hemisphericus
enlarged, showing the inter-ambulacral area (a) and the ambulacral areas, (£.) 2. Galer-
ites hemisphericus viewed from above, a. Inter-ambulacra, b. Ambulacra. 3. Genital
and ocular disk of Hemicidaris intermedia, enlarged, c. Ocular plate, d. Genital plate.
e. Anal aperture, f. Madreporiform tubercle. 4. Spine of the same. (After Forbes.)
The tubercles are mostly omitted on figs. 2 and 3 for the sake of clearness.

closed like a pair of forceps upon animalculae or other
offensive matter that may tend to obstruct its shell. One
carries the rejected matter to another till the surface is
completely free.

The mouth of an Echinus contains the most complex
and perfect dental apparatus in all the Animal Kingdom,
although occurring in a type generally considered of a
low grade of structure. It sets at naught all theories of
Evolution, since in our progress from the simplest forms
of life it is the first instance of a dental apparatus, and
the most perfect of all. It is composed of five accurately-
htting vertical pyramids, each provided with a rod-like
tooth, worked by a couple of beautifully arranged mus-
cles. (Fig. 90.) The intestine is tortuous and connected

KADIATA.

189

a

a

by delicate mesenteries to the shell. These animals pos-
sess a heart with an aorta surrounding the gullet and in-
testine. The blood

is aerated by ex- o

posure to the ox-
ygen mixed with
the water which is
constantly circula-
ting over the vas-
cular mesenteries.

The metamor-
phosis of Echinus is
very curious. The
embryo is a free
swimming minute
ciliated creature,
strangely like a
painter's easel, and
hence called a Pluteus. \_Pluteus, a penthouse.] This
passes through a strange cycle of changes. The diges-
tive canal appears in the middle of the frame, which
gradually disappears, the future Echinus is sketched in,
and a radially symmetric animal results, totally unlike its
predecessor. (Fig. 91.)

Regular Echini, as the common Cidaris, are nearly
globular, and the oral and anal openings are opposite.
Irregular Echini, as the Clypeaster and Spatangus, are
flat, or discoid, with hair-like spines, and the rows of am-
bulacra form a five-rayed star on the back of the shell.
Spatangus has no dental apparatus.

The order HOLOTHUROIDEA, embraces what are com-

FIG. 90. — Dentary Apparatus of Echinus, or Aristotle's
Lantern. The right-hand diagram shows three of the teeth
in position, a a. Cutting edges of the teeth, which are ex-
tremelyhard. b. Fibrous roots of the teeth, cc. Opposed
bony surfaces of the jaws, d d. Arched processes. The
left-hand diagram shows an isolated pyramid, e. Exter-
nal surface. Other letters as before.

190

THE SCIENCE OF LIFE.

monly known as Sea-slugs, Sea-cucumbers, or Trepangs.

The body is elongated and soft, with a tough contractile

skin containing calca-
reous spicules. One
end, the head, has a
simple aperture for
a mouth, encircled
with feathery tenta
cles. In the Holo-
thurice proper, loco-
motion is effected by
rows of ambulacral
tube-feet, but in the
Synaptidce there are
no ambulacra, and
the animal moves
9 by means of anchor-
shaped spicuta which
are scattered in the
integument. Animals
of this order have

FIG. 91. — Embryonic development of Echinus: — the singular DOWCr of
A. Pluteus larva at the time of the first appearance

of the disk. a. Mouth in the midst of the four-pronged ejecting all their in~
proboscis. £. Stomach, c. Echinoid disk, dddd.fovit

arms of the Pluteus body. e. Calcareous frame-work, temal Organs, SUTviv*-
./". Ciliated lobes, g g g g. Ciliated processes of the . ,« i /• «i
proboscis. B. Disk, with the first indication of the lng tne 1OSS Ol tnCSC
cirrhi. C. Disk, with the origin of the spines between ~oH-c otirl aff/^r«ro,-r1
the cirrhi. D. More advanced disk, with the cirrhi PartS> a!K
and spines projecting considerably from the surface. t*pr>T"OflllcinP" I'll PIT!
(N.B. In figs. B, C, and D, the Pluteus is not repre-
sented, its parts having undergone no change, save in Their Vermiform lar-
becoming relatively smaller.)

va has no skeleton.

6. The Radiate type of animal life well illustrates the
intellectual plan, or typical design, of living forms, and

RADIATA. 191

contains many instances totally unaccountable on any
scheme of material gradation whatever. The nettling
thread-cells, or Cnidce in the Hydroids, the peculiar alter-
nation of generations in the Medusae, the great amount
of muscular development in the Crinoida, the pedicel-
lariae, and the dental apparatus of Echinus, are all exam-
ples of structural arrangement for a purpose, and make
against the theory of evolutional development, or sur-
vival of the fittest. Each of these structures are the
most perfect of their kind, and seem to have no previous
structure from which they have developed, as they have
left no succeeding apparatus analogous or homologous
to them.

1 92 THE SCIENCE OF LIFE.

CHAPTER XIII.

MOLLUSCA.

I have seen

A curious child applying to his ear
The convolutions of a smooth-lipped shell,
To which, in silence hushed, his very soul
Listened intensely, and his countenance soon
Brightened with joy ; for murmuring from within
Were heard sonorous cadences whereby,
To las belief, the monitor expressed
Mysterious union with its native sea.

— WORDSWORTH.

1. THE type of Mollusca, or soft-bodied animals, is in-
dicated by the name, derjved from the Latin mollis, soft.
Like other types it embraces species of various degrees
of complexity of structure, and of various forms. It in-
cludes soft-bodied, unjointed animals, possessing a mus-
cular skin, or mantle, generally protected by a calcareous
shell, and whose nervous system is scattered. It is sub-
divided into i. MOLLUSCOIDA, containing the classes
Polyzoa, Tunicata, and Brachiopoda; and 2. TRUE MOL-
LUSCA, embracing the classes Lamellibranchiala, Gaster-
opoda, and CepJialopoda.

2. POLYZOA (Gr. polus, many, and zoon, animal) derive
their name from the fact of their living in clusters or
colonies. They are sometimes called Byozoa, (Gr. byon,
moss, and 20011, animal,) or Sea-moss. They greatly re-
semble the Hydroid polyps, but from the greater complex-
ity and character of their organization they have been

MOLLUSCA.

193

removed to this type. The cells of a group are not con-
nected with a common tube, as in Caelenterates, and each
animal possesses a
distinct alimentary
canal and nervous
system. Sometimes
the colonies are foli-
aceous, or leaf-like,
as the Sea Mat,
Flustra, (Fig. 92,)
and at others plant-
like, as the Phimat- FlG 92._SeaMati (Flustra /oliacea.) A. Magnified.

ella. (Fig. 93.) They B- Natural size-

sometimes spread over rocks and sea-weeds like delicate

lace-work, and the majority are coral-making animals, or

FlG. 93. — Plumatella. a. Natural size. b. A group enlarged, c. Anal orifice.

secrete carbonate of lime. The mouth of each animal is
surrounded by ciliated tentacles which serve for prehen-

194 THE SCIENCE OF LIFE.

sion, circulation, and respiration. Many species are fur-
nished with organs of a remarkable and peculiar kind,
called Avicularia, (avicula, a little bird,) or " bird's
heads," which during life, and even after the death of
the animal, keep up a continual motion, see-sawing, and
snapping, and opening their jaws in the most singular
manner. Their use is unknown, but Mr. Gosse conject-
ures that they may seize and hold minute animals until
decomposition attracts a crowd of Infusoria, which may
serve the Polyzoan for food. Some species of Polyzoa
are found in fresh water.

3. TUNICATA, named from the Latin tunica, a cloak,
is a class of Molluscoida which are enveloped in a tough,
leathery sac, or " test." This sac is double-walled, but
not capable of protrusion. The mouth of the animal
opens into the bottom of a respiratory sac whose walls
are lined by a net-work of blood-vessels. The tubular
heart exhibits the curious phenomenon of reversing its
action at brief intervals, so that the blood oscillates
backward and forward in the same vessels. The wall of
the tunic contains cellulose, which is generally a vege-
table product.

These bottle-shaped creatures are found in the ocean,
" solitary," attached to rocks or sea-weed, and often
glued together in bunches. Sometimes they are in " so-
cial " groups, as in Fig. 94, or " compound," as Fig. 95.

The Salpce are free swimming, transparent Ascidians,
(askos, a bag ; eidos, like,) or Tunicates, often found ad-
hering to each other in long chains, which give birth to
solitary individuals of different form by alternation of
generations.

MOLLUSCA.

195

Young Tunicata swim, like tadpoles, by a tail, which
contains a peculiar rod-like body, consisting of nucleated

FIG. 94. — A. Group of Perophora, (enlarged,) growing from a common stalk : — B. Sin-
gle Perophora. a. Test. b. Inner sac. c. Branchial sac, attached to the inner sac
along the line c' . c' . e. e. Finger-like processes projecting inward, f. Cavity between
test and internal coat, f . Anal orifice or funnel, g. Oral orifice, g* '. Oral tentacula.
h. Downward stream of food, h' '. OZsophagus. i. Stomach, k. Vent. /. Ovary. (?)
n. Vessels connecting the circulation in the body with that in the stalk.

FIG. 95. — Botryllus violaceus : A. Cluster on the surface of a Fucus. B. Portion of
the same enlarged.

cells like the chorda dorsalis, or notochord ; an elongated
mass of cells in the Vertebrate embryo, which is after-

196 THE SCIENCE OF LIFE.

ward replaced by the vertebral column. From this re-
semblance the partisans of evolution have claimed that
this simple cellular structure is the prototype of that
which distinguishes the higher animals, and that from
the simple Ascidian the Vertebrate has been developed.
Such foreshadowings of higher types is not uncommon.
It will require, however, much greater evidence to prove
transmutation than such resemblances.

4. BRACHIOPODA are protected by a bivalve shell,
which is lined by an expansion of the integument, or
" mantle." The valves of the shell are applied to the
dorsal and ventral sides of the body. The ventral valve
is usually larger and more convex than the other ; but
they are symmetrical, that is, a vertical line from the
hinge divides the shell into equal parts. The ventral
valve generally has a hole, or foramen, through which a
fleshy foot protrudes for attachment. The mouth is
furnished with two long arms, fringed with cirri, gener-
ally coiled up and supported by a bony frame-work in
the shell — the " carriage-spring apparatus." As there
are no gills, the animal respires by the arms or the man-
tle. Brachiopods were once very abundant, over two
thousand extinct species having been described ; but
less than one hundred species are now living.

In all the Molluscoida the nervous system consists of
a single ganglion, or of a principal pair with accessory
ganglia placed between the oral and anal apertures, or
on the ventral surface of the body. Some naturalists
connect them with the Worms.

5. LAMELLIBRANCHIATA (Lat., lamella, a plate ; Gr.,
bragchia, gill) comprise the ordinary bivalves, as the

MOLLUSCA. 197

Oyster, Mussel, and Clam, and are characterized by the
possession of lamellar gills. The shells differ from those
of Brachiopods in being placed on the right and left sides
of the body, so that the hinge is on the back of the ani-
mal, and in being generally unequilateral and equivalved.
They are sometimes termed CONCHIFERA, or shell-fish,
(Lat., concha, a shell ; fero, I carry.)

The shells of Mollusks are epidermal structures. The
mantle, or loose skin, secretes calcareous matter in. lay-
ers, converting the epidermis into shell. The micro-
scopic structure is so characteristic that a thin section of
a fragment often suffices to determine the group to which
it belongs. A large class of shells is formed like the
Oyster, of three parts; the external epidermis, brown
and of a horny texture ; the prismatic portion, consist-
ing of minute columns set perpendicularly to the surface ;
and the internal nacreous, or pearly layer, made up of
very thin plates whose edges overlap and form wavy
lines. In many cases the prismatic and pearly layers
are traversed by minute tubes. The pearls of commerce,
found in the mantle of some Mollusks, are similar in
structure to the shell ; but what is the innermost layer
in the shell is outside and much finer in the pearl, which
is formed around some nucleus, as an organic particle
or grain of sand.

Shells of one piece are called " univalves," as the snail.
Others, as the Clam, are of two parts, and are called
" bivalves." The ribs, ridges, and spines on the outside
mark successive periods of growth, and correspond with
the age of the animal. Figs. 96 and 97 show the princi-
pal parts of ordinary bivalves and univalves. The valves
17*

198

THE SCIENCE OF LIFE.

of a bivalve are generally equal, except in Brachiopods
and in the Oyster. The umbones, or beaks, are a little
in front of the center, and turn toward the mouth of the
animal. The valves are joined by a ligament near the

FlG. 96. — a. b. Length of the shell, c. d. Height, e. Lunula, above which is the sum-
mit, d. The ventral or inferior edge.

A B

FIG. 97. — A. The line across marks the thickness of bivalves. B. a. Anterior extrem-
ity, b. Posterior, c. d. Muscular impressions, e. f. Palleal impression, g. Lower
edge of the left valve.

umbones, and often also by a " hinge " formed by the
" teeth " of one valve locking into cavities of the other.
The aperture of a univalve is sometimes closed by a
horny or calcareous plate, called an " operculum"

MOLLUSCA.

199

Lamellibranchs breathe by
four plate-like gills, two on each
side, underneath the mantle.
(Fig. 98.) In the higher forms
the mantle is rolled up into two
tubes, or siphons, for the inha-
lation and exhalation of water.
The mouth opens into the stom-
ach, which lies imbedded in a
large liver, and the intestine,

FIG. 98. — Diagrammatic Transverse
after a few turns, passes direct- Section of Anodon, through the heart.

. a. a. Lobes of mantle, b. b. Gills, show-

ly through the heart. (Fig. 99.) ing transverse partitions, c. Ventricle
rr^i • , r of heart, d. d. Auricles, e. Pericardi-

The nervous system consists of um f Glandular sac of organ of Bo-
three pairs of ganglia, and the Ja™5- * Vestibu1!; or middle sac.

h. Venous sinus, k. Foot. A. A. Bran-
heart has tWO' Chambers, an aU- chial or pallial chamber. B. B. Epi-

branchial chamber, communicating

ricle and ventricle, and, in some with cloaca,
cases, two auricles and a ventricle. The ventricle pro-
pels the blood into the arteries, by which it is distributed
through the body. From the arteries it passes into the
veins, and is conducted to the gills, where it is aerated,
and is finally returned to the auricles.

A few Lamellibranchs are fixed, as the Salt-water
Mussel, which hangs to the rocks by a cord of threads
called "byssus," and the Oyster, which habitually lies
on its left valve ; but the rest have a foot by which they
creep about. There are more than four thousand living
species, fresh water and marine, which range from the
line of shore to the depth of a thousand feet.

The muscular impressions on the shell, (c. d., Fig. 97 ;)
the presence of a pallial sinus, e., which indicates the
possession of siphons ; the structure of the hinge, and

2oo THE SCIENCE OF LIFE.

the symmetry of the valves, are the chief characters for
distinguishing genera and species of this class, which

FIG. Q9. — Anatomy of a bivalve Mollusk, (Mactra.) «. Shell-muscles, b. Ganglia.
c. Heart, d. Liver, e. Mouth, f. Labial tentacles, g. Foot. h. Stomach. /.Intestine.
k. Anus. m. Mantle, n. Branchiae, o. Base of inhalent siphon. /. Base of exhalent
siphon.

has been divided into groups, based on the possession
or non-possession of siphons, as follows :

Section A. Asiphonidce. Without respiratory siphons,
so that the shell shows the pallial line simple, and not
indented. As in the families of Oysters, (Ostreid&l)

MOLLUSCA. 201

Mussels, (Mytilidcs^) Wing-shells, or Pearl Oysters, (Av-
iculid&l} and River Mussels, (Unionidcs^}

Section B. Siphonida. Having siphons.

(i.) Integro-pallialia. Siphon short, pallial line sim-
ple, as in the families Tridacnidce, Cardiadce, (Cockles,)
and Cyprinidce, (Heart-cockles.)

(2.) Sinu-pallialia. Long siphons, pallial line sinu-
ated, as in Venerida, (Clams,) Mactridcz, Solenidce, (Ra-
zor-shells,) and Pholadidce, (Boring-shells.)

6. GASTEROPODA, (Gr., gaster, stomach ; pous, foot.)
This class derives its name from the fact that loco-
motion is usually effected by a muscular expansion
of the under surface of the body, termed the " foot."
It includes all the univalve shells, the naked slugs, the
Dorsibranchs, the Pteropods, and the Multivalvular
Chiton.

The body of most Gasteropods is unsymmetrical, the
organs not being in pairs, but single, and on one side,
instead of central. The mantle is continuous round the
body, not bilobed, as in Lamellibranchs. A few, as the
Garden-snail, have a lung, but the majority breathe by
gills. The head is more or less distinct, and is provided
with two tentacles, with auditory sacs, or rudimentary
organs of hearing at their bases. The eyes are some-
times quite conspicuous. The Snail, for example, carries
two ocelli, or simple eyes, on the tip of its long tentacles.
Each consists of a globular lens, of short focus, which is
a part of the transparent cornea, with a colored mem-
brane (choroid) and a nervous net-work (retina) behind.
The arrangement for retracting the eye and tentacle is
seen in Fig. 100.

202

THE SCIENCE OF LIFE.

The mouth of Gasteropods possesses a peculiar strap-
like organ, the odonto-
phore, (pdous, tooth ; phero,
I bear.) It is studded with
three or more rows of lin-
gual teeth, formed of sili-
ca, which are the serrated
edges of minute plates, the
number of which varies in
different species; the gar-
den Slug has one hundred
rows with one hundred

o«/-J <»irrV»4"tr f*a<»fVi in e*ir\\

FIG. too.—

structure of tentacles: a. Right inferior ten- j-QW. (Fig". IOI.) The Strap
tacle retracted within the body. b. Right su- ' \ S* V

perior tentacle fully protruded, c. Left superior or " tOngUC," playS OVCr 3.
tentacle partially inverted, d. Left inferior

tentacle. /. Optic nerve, g. Retractor mus- CartilaginOUS Cushion, Of
cle. k. Optic nerve in loose folds. /.Retractor . . . . ,

muscle of head. *. Nerve and muscle of left pulley, Connected With the

lower jaw, and the teeth
are renewed by fresh growths
from the membrane beneath.
The gullet is long, and frequent-
ly expands into a crop ; the
stomach is often doable, the an-
terior being a gizzard provided
with teeth for mastication ; the
intestine passes through the liv-
er, and ends in the fore part of
the body, usually on the right
side. The heart is double, and
FIG. loi.— Palate of Buccinum a capillary system intervenes be-

undatum, as seen under polarized

light. tween the arteries and veins, but

inferior tentacle. /. m. Nervous collar.

MOLLUSCA. 203

the liver does not possess a distinct portal system, as in
Vertebrates. (Fig. 102.)

FIG. 102. — Anatomy of Turbo Pica : /. Foot. o. Operculum. t. Proboscis, ta. Tenta-
cula. y. Eyes. m. Mantle opened longitudinally, to show the disposition of the respira-
tory cavity, f. Anterior border of the mantle, which, in its natural position, covers the
back of the animal, leaving a wide slit by which the water enters the branchial cavity.
b. Gills, vb. Branchial vein, returning to the heart, c. ab. Branchial artery, a. Anus,
z. Intestine, e. Stomach and liver, ov. Oviduct. On the upper side of the neck are seen
the cephalic ganglion, and the salivary glands ; and at d. is shown a fringed membrane,
which forms the lower border of the left side of the opening that leads to tne respiratory
cavities.

The univalve shell is generally a coiled tube, wound
round a central axis, or columella; the nucleus, or earli-
est part of the shell being at the apex, and the portion
last formed being the open mouth at the lower part, 01
base. The direction of the coil may be concentric, form-
ing a discoidal shell, as Planorbis, but it is generally a
true spiral. The mouth, or aperture, of the shell is en-
tire in most vegetable-feeding Gasteropods, and notched
or produced into a canal for the siphons in the carniv-

204

THE SCIENCE OF LIFE.

orous species. The former are generally land and fresh-
water forms, and the latter all marine.

Gasteropods comprise three fourths of all living Mol-
lusks, and are representatives of the type.

Omitting a few rare forms, as Dentalium and Carin-
aria, we may divide the class into the following orders :

1. Pteropods, (Gr., pteron, wing ; pous, foot,) which are
small marine floating Mollusks, whose main organs re-
semble a pair of fins or wings, whence the common name,
" Sea-butterflies." Many have a delicate, transparent
shell. The head is said to carry six appendages, armed
with several hundred thousand suckers, forming a pre-
hensile apparatus unequaled in complication.

2. Opisthobranchs, (Gr., opisthon, behind ; bragchia,

FIG. 103.— A. Tritonia Hombergi. B. Horned Doris.

gills.) These are generally naked Sea-slugs, a few only
having a small shell. The feathery gills are behind the
heart, (whence the name.) They are found in all seas,
generally on rocky coasts. When disturbed, most of
them draw themselves up into a lump of jelly or tough
skin. These naked-gilled Mollusks (Niidibranchiatd) ex-

MOLLUSCA.

205

hibit a great diversity of form and a variety of beautiful
colors. The Sea-lemon, (Doris,} the beautiful Tritonia,
(Fig. 103,) the painted Eolis, the Sea-hare, (Aplysia,)
which emits a violet or reddish fluid from the man-
tle when alarmed, and
the Bubble-shell (Bui-
la) are examples.

The embryo of the

naked-gilled Mollusks /V^l / I t\
is very minute, and
resembles a Rotifer

rather than a Mollusk. FlG" '^-Embryos of Nudibranchiate Gasteropods.

It is inclosed in a transparent nautilus-like shell, pro-
vided with an operculum. (Fig. 104.)

FIG. 105. — Snails and Slugs.

3. Pulmonates (having lungs) are air-breathing Gaster-
opods, represented by the common Snail. They have
18

206

THE SCIENCE OF LIFE.

the simplest form of lung — a cavity lined with a delicate
net-work of blood-vessels, which opens externally on the
right side of the neck. This opening is covered by a
valve. They are found in all zones, but most where lime
and moisture abound. All feed on vegetable matter. A
few are naked, as the Slug ; some are terrestrial ; oth-
ers live in fresh water. The Land-snails, as the Helix,
Bulimus, and Limax, (Slug,) have four horns, the short
front pair being the true tentacles, and the long hinder
pair the telescopic eyes. The Pond-snails, as Limnaa
and Planorbis, have no eye-stalks, the eyes being at the
base of the tentacles. They are obliged to come to the
surface of the water to breathe. (Fig. 105.)

FIG. 106. — Chiton.

FIG. 107.— Fissurella Reticulata.

4. Prosobranclis.
(Gr.^proson, before

Having gills in front of the heart.
bragchia, a gill.) These are aquatic
and generally marine animals, the
most highly organized and most
abundant of all the Gasteropods.

Among the lower forms ate the
singular Chiton, (Fig. 106,) covered
with eight shelly plates ; Limpet, (Pa-
tella^] well known to every sea-side
visitor ; and the beautiful Ear-shell Abalone, (Haliotis^)
(Fig. 108,) often used for ornamental work and jewelry.

FIG. 108.— Ear-shell, or
Haliotis. Reduced.

MOLLUSCA.

207

In the higher Prosobranchs the gills are comb-shaped
and the sexes are distinct. The group includes all the
spiral univalve sea-shells and a few fresh-water shells.
Many have the aperture entire, as the fresh -water
Paludina, the pyramidal Trochus, pearly Turbo, and

FIG. 109. — The Wentle-trap, (Scalana.)

FIG. no. — Volute Crawling.

FIG. in. — Murex.

common Periwinkle (Littorind] from the sea. Others,
the highest of the race, have the margin of the aper-
ture notched or produced into a canal, and are carniv-
orous and marine ; such are nearly all the more beauti-
ful sea-shells, as the Cowry (Cyprced] Volute, (Fig. 1 10,)

208

THE SCIENCE OF LIFE.

Olive, Cone, Harp, Murex, (Fig. in,) Whelk, (Fig. 112,)
and Winged-shell, (Fig. 113.)

FlG. 112. — The Whelk, (Bitccinuui,) showing its operculum.

7. CEPHALOPODA, (Gr., cephalc, head ; pous, foot.) The

class of Cephalopods stands
at the head of the Molluscan
type. Some of its forms sur-
pass in complexity of struct-
ure the highest Articulates,
although not so representa-
tive of their type as the Gas-
teropods. They are aquat-
ic free-swimming or creeping
Mollusks, inclosed in a mus-
\LL--y cular mantle, and in some

. 113. — Strombus gigas, or Winged-
shell ;" one fifth natural size. West Indies. spCClCS having a Univalve

shell. The foot is divided into eight or ten long, wav-
ing, but strong tentacles, bearing numerous suckers, or

MOLLUSCA.

209

acetabula. The adhesion of these suckers is so great
that it is easier to tear away a limb than to detach it.
Their mechanism may be understood from Fig. 1 14.
The mouth has a horny beak, like a parrot's bill, but the
jaws do not move vertically, like the bird's. A long
gullet ends in a muscular gizzard, resembling that of a
fowl. Below this is a cavity, the stomach or duodenum,

FIG. 114. — Suckers on the Tenta-
cles of a Cuttle-fish : a. Hollow axis
of the arm, containing nerve and ar-
tery, c. Cellular tissue, d. Radi-
ating fibers, h. Raised margin of
the disk around the aperture f, g^
which contains a retractile mem-
brane, or " piston," z".

FIG. 115. — Morphology of
Cephalopoda. Sepia oflkina-
hs, laid open to show viscera,
etc. a. Foot. b. Horny jaws.
c. Principal ganglion, d. Sal-
ivary gland, e. OZsophagus.
f. Liver, g. Stomach, h. Py-
loric caecum. i. Ink bag.
k. Ovary. /. Aperture of
atrial system, m. Branchiae.
n. Oviduct, o. Cuttle-bone.

which receives the bile from a large liver. The intes-
tine is a tube of uniform size, which, after one or two
slight curves, bends up, and opens into the " funnel "
near the mouth. (Fig. 115.) The head is set off from
the body by a slight constriction, and is furnished with

a pair of large, staring eyes, which are constructed like

18*

210 THE SCIENCE OF LIFE.

the eyes of Vertebrates, except that there is no aqueous
humor, and the lens, which is double, is bathed freely
by the water in which the animals swim. The nervous
system is more concentrated than in other Invertebrates ;
the cerebral ganglia are even inclosed in a cartilaginous
cranium. All the five senses are present. The integu-
ment contains pigment sacs, or chromatophores, which
sometimes tint the animal with variegated colors. It is
probable that they in some way subserve the sense of
sight, as the animal swims with its head backward.
Some Cephalopods have an internal shell, secreted by a
fold of the mantle, called the " cuttle-bone" or " pen."

Two or four pairs of plume-like gills are situated in
the pallial cavity, into which the sea-water is admitted
at one end and expelled through the funnel at the other
by muscular contraction. These contractions serve both
for respiration and locomotion, the pressure of the ex-
pelled water driving the animal in an opposite direction.
The systemic heart pumps the blood all over the body,
which then returns through capillaries into veins which
conduct the blood back to the gills, where it is purified,
and whence it is propelled to the heart by contractile
sacs, called branchial hearts, placed at the base of each
gill. In addition to other viscera, a large secreting sac,
the ink-bag, is often present, containing a dark fluid
which the animal ejects at will through a duct opening
at the base of the funnel. The sexes are always distinct.
During reproduction the spermatozoa are temporarily
transferred to one of the arms, which becomes curiously
altered and unfit for locomotion ; in this condition it i«
said to be hectocotylized.

MOLLUSCA.

211

I.) Tetrabranchs. This order has four gills, forty or
more short tentacles, and an external chambered shell.
The partitions of the shell are united by a tube, called a
siphuncle, and the animal lives in the last and largest
chamber. These chambered shells were once very abun-
dant. More than two thousand fossil species are known,
among which are the Nautilus, Ammonite, and Ortho-
ceros. They have but one living representative — the
Pearly Nautilus. This straggler of a mighty race dwells
at the bottom of the Indian Ocean. The shell is well
known, but only two or three specimens of the animal
have been obtained.

2.) Dibranchs. Those having two gills. They are the
most active of Mollusks, and the tyrants of the lower

FIG. 116.— The Paper Nautilus, (Argonauta Argo.) Fig. i. Swimming toward the
point a. 2. Walking on the bottom. 3. Contracted within its shell, which is partly
embraced by the arms.

tribes. There are Cuttle-fish and Poulps (or Devil-fish)
so large as even to be dangerous to a man who might be
swimming near them, and the stories of novelists like

212

THE SCIENCE OF LIFE.

Victor Hugo have some foundation in the large size and
repulsive aspect of these creatures. They crawl with
their arms on the bottom of the sea, head downward,
and also swim backward or forward, usually with the
back downward, by means of fins, or squirt themselves
backward by forcing water through their funnels.

The Paper Nautilus (Argonaut a) (Fig. 116) and the
Poulp have eight arms. The Squid (Loligo) and Cuttle-
fish (Fig. 117) have ten arms, the additional pair being

FIG. 117. — Cuttle-fish.

longer than the others. Their eyes are movable, while
those of the Argonaut and Poulp are fixed. The Squid,
used for bait by cod-fishermen, has an internal horny
" pen," and the Cuttle has a spongy, calcareous bone.

ARTICULATA. 213

CHAPTER XIV.

ARTICULATA.

" Yet wert thou once a worm — a thing that crept
On the bare earth, then wrought a tomb, and slept !
And such is man ; soon from his cell of clay
To burst a seraph in the blaze of day ! " — ROGERS.

I. THE Articulated type of animals (Lat., articulus, a
joint) includes all which possess a distinctly jointed
body, as Worms, Crustacea, and Insects. It contains a
greater number and variety of forms than all the other
types put together. The nervous system consists chiefly
of a double chain of ganglia along the ventral surface of
the abdomen, connected together by nerve-filaments.
The part representing the brain is in the form of a ring
encircling the gullet. The circulatory apparatus is a
tubular structure running along the back, and communi-
cating with the body-cavity. The limbs, when present,
are jointed and hollow, and on the same side as the
nerve-cords.

There are five classes of Articulates : the aquatic
Worms and Crustaceans, and the air-breathing Spiders,
Myriapods, and Insects. It must be remembered, in
accordance with the principles so often referred to in the
present work, that the order of classes in a type is one
of relation rather than of structural rank. Classes can-
not be arranged serially, any more than species, as if one
was an improvement on another, by progressive devel-

214 THE SCIENCE OF LIFE.

opment. In many respects Myriapods are like Worms,
yet their heads show a resemblance to Insects. Some
Spiders are less complicate than Myriapods, yet for their
wonderful instincts Owen places them above Insects.
Insects begin life as worm-like embryos. Classes in the
articulate type depend on the equal or unequal develop-
ment of the body-segments, and the number and form
of appendages. Articulates with jointed appendages
articulated to the body are called Arthropoda, (Gr., art/i-
ron, a joint ; podes, feet.)

2. The class of WORMS, called, also, Annelida, or An-
nulata, (Annulus, a little ring,) includes animals with a
soft skin and a body formed of a succession of rings, or
movable joints. They differ from the Anthropoda in
not having jointed limbs. A water-vascular system ex-
ists, but it has no connection with locomotion. The
blood is often reddish, but the color does not depend on
colored corpuscles, as in vertebrates. The circulatory
apparatus is more highly developed than in Insects.

Some worms can only live as parasites upon the blood
or juices of other animals, and in these the circulatory,
water-vascular, and digestive systems become rudiment-
al, the nervous system is undeveloped, the body-cavity
often vanishes, and the reproductive organs alone are
fully represented.

Order i. Tceniada ; (tcenia, a tape.) Tape-worms, so
called from their length and flatness. They live chiefly
in the digestive canal of higher animals. Three species
are occasionally parasitic in man. The head, which is
the true animal, is provided with hooks or suckers, by
which it adheres to the mucous membrane of its host.

ARTICULATA.

215

It feeds by imbibition, (osmosis,} there being no mouth
or alimentary canal. The joints, or segments, are called
proglottides, (singular, proglottis^} and are but successive
growths containing ova. The life-history of these worms
is a curious instance of alternation of generations. The
fertilized ova are set free by the decomposition of the
joint, or proglottis. They are then swallowed by some
animal, and the tough capsule is dissolved, setting free
the embryo, which travels through the tissues of its host
as a little oval body, bearing weak, hook-like, or boring
spines. On reaching a suitable site, as the liver, it an-
chors, and the body dilates into a cyst, or sac full of
water, (Cysticercus^) Many animals, formerly known as
cystic worms, have been found to be but transitional
stages of Taeniae. In this condition the animal may

FIG. 118. — Morphology of Taeniada. a. Ovum with contained embryo, b. Cysticercus
longicollis. c. Head of Tsenia solium, (enlarged ;) the circlet of hooklets is at the top,
and below them are those of the cephalic suckers, d, A single segment or proglottis
magnified, i. Generating pore. 2. Water vessels. 3. Dentritic ovary, e. Portion of
Tape-worm, natural size, showing the alternating arrangement of the generative pores.

remain a long while and generate new cysts by budding,
but when the flesh containing the " scolex," or resting-
larva, is eaten by some other animal, the outer wall of the
cyst dissolves, and becomes a true Tape-worm. The hu-
man Tape-worm has its cystic stage in " measly" pork,

Of

HIE SCIENCE OF LIFE.

while the Tape-worm of the dog develops from cysts
found in the hare, and that of the cat from cysts in the
mouse ; most cases requiring two animals as hosts for
perfecting the growth of the worm. (Fig. 1 18.)

Order 2. Trematoda ; the Flukes. (Gr., trema, a hole.)
These are flat or roundish parasitic worms. The intes-
tine is branched, and, as in Coelenterata, there is but a
single opening, which serves for both mouth and anus.
There are suckers at the anterior end of the disk. They

are met with sometimes in
the liver of the sheep.
•Order 3. Turbellaria.
These are non- parasitic,
and may be found on the
sea-shore, under stones, or
in fresh-water pools, or on
moist ground. They are
small, ciliated, and flat
worms, which glide with a
slug-like motion over wet
surfaces, or swim by the
vibrations of their cilia.
In the small flat Plana-
rians the digestive cavity
is greatly branched. (Fig
1 19.) In others it is a sim-

II9.-Structure of Polycelis levigatus,
(Planarian worm.)

ple pouch, with no

^ °rifice' In the
forms It is elongated. Some

of the largest (the Nemerteans] are like long ribbons;
sometimes, as in Borlasia, being twelve feet long.

ARTICULATA. 21?

Order 4. Acanthocephala ; (akantha, a thorn; cephale,
head,) are rounded, parasitic worms, having a protrusible
proboscis, armed with recurved hooks. Their structure
is not unfrequently as simple as the Protozoa, having no
alimentary canal whatever, and subsisting by abrorption.
Like the Tape-worms, they develop through an alterna-
tion of generations.

Order 5. Gordiacece. The horse-hair-like worm found
in rain pools is an example of this order. It begins life
as a little larva in mud or water pools. By means of its
boring spines it pierces the body of a grasshopper, bee-
tle, or other insect, where it becomes encysted; and
grows often ten times as long as its host, when it be-
comes free and aquatic, and produces its eggs. Some of
these, as the Mermis albicans, multioly so rapidly as to
give rise to a popular belief that they fall as " worm-
rains." They have remarkable tenacity of life, as they
can be dried into brittle threads, and yet become active
on being moistened.

Order 6. Nematoidea, (nema, thread ; eidos, form.)
Thread-worms, or round worms. These are both free
and parasitic. Some of them, as the Ascaris lumbticoi-
desy or common round worm, often infests the small
intestines of children, while the Trichina spiralis, a mi-
nute worm found encysted in the flesh of swine , when
introduced into the human body, multiplies so rapidly
in the muscles as to give rise to dangerous, and even
fatal symptoms. The " eels " in vinegar and sour paste
also belong to this order.

Order 7. Rotifer a, or Wheel Animalcules. These are

microscopic in size, but so transparent that the details
19

218

THE SCIENCE OF LIFE.

of organization can easily be seen. The male rotifers
are few and small, and have no digestive canal, but the
females have a complete nutritive system,
and many species are provided with an organ
for mastication resembling an anvil acted on
by two hammers, another instance of pecul-
iarity of structure for a special end. These
animals are capable of reviving on being
moistened, after having been dried up, and
that many times in succession. (Fig. 120.)

Order 8. Gcpliyrca, (gephura, a bridge,) so
called in allusion to the apparent connection
which they exhibit between Echinoderms and
Articulates. They are sometimes called
Spoon -worms, Squirt -worms, and Siphon-
worms, (Sipunculus.) They have all the as-
pect of worms, but the circle of tentacles
FIG. i2o.-Ro- round the mouth show their affinity to Ho-
lothurians. They live in the sand, or seek
protection in some empty univalve shell. Their elon-
gated bodies contain a long, tortuous intestine, ciliated
inside and outside. They have no locomotive processes,
nor are there calcareous or silicious spicules in their skin.
The mouth has a long proboscis.

Order 9. Suctoria, or Leeches. These are aquatic
worms, with a soft, segmented body, provided with a
suctorial disk at one or both ends. The mouth of the
common Leech (Hirudo medicinalis) is armed with three
horny, semi-lunar plates, with finely serrated teeth, which
act as saws, enabling the leech to make incisions in the
skin of its host through which to suck the blood.

ARTICULATA. 219

Order 10. Chcetopoda, or Bristle-footed worms. Some
of these occur under the stones of the sea-shore, as the
lug-bait of fishermen. (Fig. 121.) Others se-
crete a glutinous material from the surface,
which cements sand and other foreign bodies
into a tube. Others secrete calcareous matter,
which forms a tubular residence, as the com-
mon Serpula, whose white, snake-like concre-
tions abound on the stones and shells of the
shore, and the Spirorbis, whose minute whorled
shells dot the surface of many sea-weeds.
Some of the Nereids, or Sea-centipedes, attain
to a considerable size, one species being four
feet long. The Sea-mouse (Aphrodite] also be-
longs to this order. The latter is clad with
iridescent scales and bristles, or barbed spines.
Those who bear the gills along the back have
been called Dorsibranchiates. These gills are
found close to the root of the dorsal oar, or
bristle, and the blood is purified by being ex-

FlG. 121. —

posed to the oxygen held in solution in the Lob-worm,

r~, i • 1 1- . (Arenicola

sea-water. Those worms which live m tubes
(Tubicola) have the gills developed only on
the foremost segments of the body, and the
dorsal and ventral oars of the other joints are or the exje1r-

J nal gills. The

rudimentary, but they have branching tentacle- large head is

without eyes

like processes about the head. In Serpula one or jaws.
of the tentacles is formed into a lid, or operculum, with
which the open mouth of the tube can be closed at will.
(Fig. 122.)

The common Earth-worm (Lum&rtcus) has few and

220

THE SCIENCE OF LIFE.

small bristles, in the form of recurved hooks on each
ring of the body, which assist in locomotion. It pos-
sesses no external gills, but respires
by internal ciliated processes. The
nervous system is often but little de-
veloped. The mouth is on the second
segment, and the digestive canal is a
straight tube, which is wide, and al-
ways full of earth, which these animals
devour for the sake of the organic par-
ticles contained in it ; the remaining
part being cast out and heaped at the
outlet of their burrows, as " worm-
casts." For better division of the
FIG. ™.-serpuia. material swallowed the digestive canal
lias a muscular gizzard about fifteen rings from the
mouth. They are propagated by eggs.

3. The class of CRUSTACEA, (crusta, a crust or shell,)
includes all Articulates with jointed legs and gills. They
have a double, or complete circulation of blood ; a dor-
sal tube, or heart, sending off a system of arteries, not
found in insects; but the blood, as it leaves these tubes,
escapes into the general cavity, as in other Articulates.
(Fig. 123.) The shell, or carapace, has for its base a
horny substance called Chitine. It is also found in the
covering of Insects. In the Crab and Lobster there is
a large proportion of carbonate of lime combined with
this, rendering the carapace extremely hard. In others,
a mixture of chitine and albumen gives rise to a softer
integument. The rings of the body have considerable
freedom of motion, by means of striated or voluntary

ARTICULATA. 221

muscles. The normal number of joints is twenty-one,
but two or three are often blended. To each of these

FIG. 123. — Circulating Apparatus of Lobster : a. Heart. 3. c. Arteries to the eyes
and antennae, d. Hepatic artery, e.f. Arteries to thorax and abdomen, gg. Venous
sinus. Ji. Gills, z. Branchial veins.

joints, except the last, there is attached a pair of mem-
bers, the forms and uses of which vary in different spe-
cies, and at different ages. These members are jointed,
and covered with a similar envelope, or crust, to that of
the body. As the body grows the carapace does not
grow in the same proportion, rendering frequent molt-
ings necessary. The entire covering is thrown off from
body, feet, and antennae in the most perfect manner.
The Crustacea differ in habits as well as in structure.
Most live in the water, but the Land-crabs inhabit the
land. The Hermit-crabs (Pagurida) live in the empty
shells of Mollusks, which they seize, often killing the in-
habitant. The majority of Crustaceans have jaws and
organs of mastication, but some have no such organs,
but live as parasites, especially on fishes, sucking their
juices, and becoming strangely deteriorated. The ali-
mentary canal in this class consists of a short gullet, a

gizzard-like stomach, and a straight intestine. Crusta-
19*

222

THE SCIENCE OF LIFE.

ceans pass through a series of strange metamorphoses
before reaching their adult form. The Balanus, or
acorn-shell, which incrusts the rocks of the sea-coast in
great numbers, begins life as an active, one-eyed free
swimmer, called a " Nauplius" which after one or two
molts becomes a pupa, inclosed in a bivalve shell by a
folding of the dorsal portion. Finally it becomes a sed-

FIG. 124. — Development of Balanus balanoides : A. Earliest form. B. Larva after
second molt. C. Side view of the same. D. Stage immediately preceding the loss of
activity, a. Stomach. (?) b. Nucleus of future attachment. (?)

entary Cirripede, (cirrus, a curl ; pes, a foot.) (Fig. 124.)
It will be convenient to divide Crustaceans into four
groups, or orders.

I.) Cirripeds, distinguished by being fixed, having a
shelly covering, and by their feathery arms. Such are
Barnacles, (Lepas^) which have a peduncle, or stalk, and
are often found on the backs of whales or on ship's bot-
toms, and Acorn-shells, (Balanus^) which are sessile.

ARTICULATA.

223

2.) Entomostracans, which have a horny shell and no
abdominal limbs ; represented by the little Water-fleas,
(Cyclops^ (Fig. 125,) of
our ponds, the King-
crabs (Limulus] and the
extinct Trilobites. The
abdomen of the King-
crab is reduced to a
mere spine, the append-
ages about the mouth
are used for locomo-
tion, and their eyes are
smooth.

3.) Tetradecapods,
small fourteen - footed
species ; as the Wood-louse, or Sow-bug, (Oniscus?) found
in damp places, and the Sand-flea, (Gammarus,) seen in
summer on the sea-shore.

FIG. 125. — Water-fleas : i. Cyclops communis.
2. Cypris unifasciata. 3. Daphnia pulex.

FIG. 126. — Metamorphosis of Crustacea, (Carcinus mcenas.} a. Larval or first form.
b. Second stage, c. Third stage, d. Final stage, in which the metamorphosis is complete.

4.) Decapods, having ten legs, as the Shrimp, (Crangon^)
Cray-fish, Lobster, (Astacus^) and Crab, (Cancer^ Crabs
differ from Lobsters chiefly in being formed for creeping

THE SCIENCE OF LIFE.

at the bottom of the sea instead of for swimming, and
in the abdomen, or tail, being a mere rudiment which
folds into a groove under the enormous thorax. The
curious metamorphosis of the Crabs is illustrated in
Fig. 126. At first the embryo is a comical-looking ani-
mal, with a sort of spiked helmet on its head. It has
two large eyes and a well-developed abdomen. It is
called a "Zoea," and was formerly described as a distinct
genus. After a succession of molts it becomes a per-
feet Crab.

4. ARACHNIDA (arachne, a spider) is a class much re-
sembling the Crustaceans, having the body divided into
a cephalo-thorax and abdomen. The head carries two,
six, or eight eyes, which are not compound bundles of
crystal rods covered by a common cornea, as in Crusta-
ceans, but separate transparent cones surrounded with
pigment. Antennae are only two, if present, and are not
used as " feelers," but serve prehension of food. Man-
dibles are always present, and in Scorpions the maxillary
palps form pincers, or claws, like those of a Ciab. Such
claws are called chela, (chele, a claw.) Arachnids are all
air-breathers, having spiracles which open into air-sacs,
or tracheae. The young of the higher forms undergo no
metamorphosis after leaving the egg. The class is di-
vided into three orders : Mites, Scorpions, and Spiders.

I.) Mites are the simplest forms of the class. They
have no marked articulations, the head, body, and
thorax being in one piece. They have no brain, but a
single ganglion in the abdomen. They breathe by tra-
cheae. The mouth is formed for suction. Most are
parasitic on animals or plants. Mites (Acarus) include

ARTICULATA. 225

the Cheese -mite, the Itch -insect, and many similar
forms. The Ticks (Ixodes) have a piercing beak and a
leathery skin.

2.) Pedipalpi, or Scorpions, have maxillary palpi ending
in forceps, and a prolonged jointed abdomen. (Fig. 127.)
Breathing takes
place by pulmo-
nary sacs, similar
to spiders. The
nervous and cir-
culatory systems
are highly organ-

, rr , , FIG. 127.— Scorpion.

ized. The last

joint of the abdomen bears in scorpions a sharp spine at
its end, perforated by the duct of a poison-gland,
whereby it inflicts painful wounds. The Chelifer, or
Book-scorpion, sometimes found in old books, has no
sting. The Phalangers, or Harvest-spiders, with long
hooked palpi and long ungainly legs, belong to this
order.

3.) Araneida, or Spiders, have the cephalo-thorax
joined to the sac-like abdomen by a narrow constriction,
and are provided at the posterior end with two or three
pairs of appendages called "spinnerets." The use of the
spinnerets is to reel out the silk for their web from the
silk-glands. The tip of each is perforated by many pores,
through which the silk escapes, so that each thread of
the web may consist of several hundred strands. The
silk is fluid at first, but rapidly hardens. The hind feet
have comb-like claws for pressing the silk together.
Sometimes one pair of the hinder appendages consists

226 THE SCIENCE OF LIFE.

of palpiform organs. The mandibles are vertical, and
end in a powerful hook. The maxillae, or palpi, which in
Scorpions are powerful claws, in Spiders resemble thor
racic feet. The brain is of large size, and the nervous
system greatly concentrated.

The instincts of Spiders are very remarkable. They
are the most wily of Articulates. They display great
skill and industry in weaving their webs, and some spe-
cies (called Mason-spiders) excavate cavities in the
ground, which they line with a silken web, and close the
entrance with a lid which moves upon a hinge.

5. MYRIAPODA (myrios, numerous ; pous, foot) is a
small class, including the Centipedes and the Millipedes.
The body is divided into segments, twenty or more,
to each of which legs are appended. They resemble
Worms in their form, and in the simplicity of their nerv-
ous and circulatory systems; but the skin is hardened
by chitine and the legs are articulate. They breathe
by trachea, or tubes, have two antennae, and a variable
number of eyes.

I.) Chilognatha, (cheilos, lip; gnathos, jaw.) This or-
der contains the Thousand -legged Worm, (Julus.')
The body is round, legs very numerous, sometimes a
hundred pairs, each segment having two pairs. Mouth
without palpi. Lower lip composed of confluent max-
illae. They are of slow locomotion, harmless, and vege-
tarian.

2.) Chilopoda, (cheilos, lip ; pous, foot,) are characterized
by a flat body, with fifteen to twenty pairs of legs. The
mouth possesses a hollow duct for the passage of fluid
from a poison-gland. The terminal section of the body

ARTICULATA.

227

carries a pair of spines. Sometimes the tail is curved
into a formidable poisonous hook, as in the Scorpion.
In temperate climates the Chilopoda are harmless, but
often dangerous in hot countries. Such is the Centipede,
(Scolopendra^}

6. INSECTA. This class contains more species than
all the rest of the Animal Kingdom, 150,000 having
been already described. Its typical character is well

FIG. 128.— Diagram of Insect, (Blatta orientalist a. Head with compound eyes and
antennae, b. Prothorax with first pair of legs. c. Mesothorax with second pair of legs
and first pair of wings, d. Metathorax with third pair of legs and second pair of wings.
e. Abdomen without limbs, but carrying terminal appendages, which are subservient in
reproduction.

marked, yet it contains a large number of instances of
special structure, arranged for evident purpose. Chap.
Ill, Sec. 9, and Chap. V, Sec. 6.

The body is divided into three principal segments —

228 THE SCIENCE OF LIFE.

a head, a threefold thorax, and a ringed abdomen.
(Fig. 128.)

The head contains the organs of sense, and sup-
ports two antennae, which are supposed to be organs of
touch and of hearing, as well as of communication be-
tween one insect and another. There are many forms
of antennse, but all are tubular and jointed. The eyes
are usually compound, although there are also some-
times a cluster of simple eyes, or ocelli. The compound

eyes have a trans-
parent surface, or
cornea, divided
into many facets,
each of the nerve-
rods having its
own pigment mass
A nG',,I29'THrd and fyesf * «e Bner "' "' Af"na;- and itsown cornea.

b. Ocelli. A. Facets enlarged. B. 1 he same with hairs

growing between them. (Fig. 129.) The

common house-fly has two thousand such facets in each
eye, and in the dragon-fly there are twenty-eight thou-
sand.

The thorax consists of three pieces, the prothorax,
mesothorax, and metathorax, each having a pair of legs ;
the wings, when present, arise from the last two seg-
ments.

The abdomen contains the viscera and the organs of
reproduction. Legs are never attached to it.

The " brain," as it is called, is a mass of ganglia lying
across the upper side of the throat behind the mouth,
and the principal nerve cord, with a ganglion for each
segment, runs along the ventral side of the body.

ARTICULATA.

229

FIG. 130. — Circulation in Insects. The arrows indicate the course of the blood.

The digestive apparatus consists of pharynx, gullet,
(sometimes a crop,) gizzard, stomach, and intestine.
The liver is represented by tubes opening into the
intestine. Many insects have glandular tubes, called

a b c d e h f g

FlG. 131.— Digestive Apparatus of Beetle, a. Pharynx, b. (Esophagus, c. Crop. d. Giz-
zard, e. Chylific stomach, f. Small intestine, g. Rectum, k. Biliary vessels.

from their first describer, Malpighian, which open at
the end of the intestine. (Fig. 131.) Some have also

salivary glandular tubes and silk organs, Insects have
20

230

THE SCIENCE OF LIFE.

no absorbent vessels, the chyme transuding through the
walls of the canal. The blood, usually colorless, is pro-
pelled by a pulsating tube divided into valvular sacs,
which allow the current to flow only toward the head.

(Fig. 130.)

Head.

First Pair of Legs

First Segment of
Thorax

Origin of Wing
Second Pair of Legs
Third Pair of Legs

Tracheae
Stigmata

Air-sacs

FIG. 132. — Respiratory Apparatus of Inseet, (Neja.)

From this tube it escapes into the cavities of the body.
Respiration is provided for by a tracheal system ; the
air circulating in vessels instead of the blood, as in other
classes. A row of apertures (spiracles) on each side
of the body, often provided with a net-work of fibers

ARTICULATA. 231

to keep out foreign substances, communicate with
branching tubes, whose membraneous wall is strength-
ened and kept open by a coiled spinal filament. (Fig.
132.) What are called the " nerves" of an Insect's wing
are double tubes, the inner one being a tracheal branch
supplying air, and the outer one, sheathing it, is a blood-
vessel.

The mouth of an Insect is a very complicate appara-
tus. Some are Masticatory, or fit-
ted for biting, as in Beetles. (Fig.
133.) Others are Suctorial, or for
sucking, as in Butterflies. These
last form a long double tube, or
spiral trunk, (proboscis,) serving to
pump up the juices of flowers.
The masticating mouths consist of
two pairs of horny jaws, (mandibles FIG. i33.— Masticatory mouth

, •// \ 1 • 1 i 1 of Insect. <z. Labrum, or upper

and maxilla,) which work horizon- lip. 3. Labium, or lower HP,

tally between an upper (labrunf) lip

and an under (labium) lip. The bles<

maxillae and under lip carry sensitive jointed feelers,

(palpi.) The front edge of the labium is generally

known as the tongue, (ligula.)

In the Bee tribe, instead of maxillae, we find a sheath
inclosing a long, slender, hairy tongue. Entomologists
have retained the same names to the different parts,
under the influence of the theory of transmutation.
(Fig. 134.)

The proboscis of the Fly is an enlarged lower lip,
(Fig. 135;) that of the Bugs is formed by four bristles,
fitted both for piercing and sucking.

232

THE SCIENCE OF LIFE.

Mandible.

Maxillary Palp.

Maxilla.

Labial Palp.

Antenna

Lateral Lobes of

the Tongue. remaining

Tongue.

FIG. 134.— Head of a Bee.

Most Insects undergo metamorphosis, and exhibit
four states of existence : egg, larva, pupa, and imago.

The larva has lit-
tle resemblance to
its parent, eating
and growing rapid-
ly. It wraps itself
in a cocoon and en-
ters the pupa state,
' ig appar-
ently dead till new
organs are devel-
oped, when it emer-
ges a perfect winged
Insect, or imago.
Insects have six legs, each having five parts ; the
coxa or hip, the trocliantcr, the tibia or shank, and the

tarsus. The last
is subdivided into
joints, generally
five, and a pair of
claws. Such as can
walk on glass, or
upside down, as the Fly, have two or three disks (pul-
villi) between the claws. It used to be supposed that
these disks acted as suckers, but it is now believed that
each hair is a minute tube containing a viscid fluid by
which the Fly adheres.

The male of the Great Water-beetle (Dytiscus mar-
ginalis] has a peculiar apparatus of suckers, large and
small, on his front legs, which may be useful, but, judg-

FIG. i35.-Proboscis of a Dipterous Insect, (Tabanus.)

ARTICULATA.

233

ing from their beautiful fringes as seen under the mi-
croscope, appear rather ornamental. (Fig. 137.)

FIG. 136. — A. Larva of Mosquito. E. Escape of Mosquito from its i-u^-caae

Order I. Neuroptera ; (neuron, nerve; pteron, wing,)
includes Dragon flies, (Libellulidce, (Fig. 138;) Caddis

FIG. 137.— A. Foot of Dytiscus^ showing its apparatus of suckers, a. b. Large suckers.
c. Ordinary suckers. B. One of the ordinary suckers more highly magnified.

flies, (Plioganeidcz,} May flies, (Ephemeridce,} the Ant-
lion, (Mygonalis,) and the Termite Ants. The mouth
is masticatory ; wings four, equal in size, membraneous

and lace-like.
30*

234

THE SCIENCE OF LIFE.

Order 2. Orthoptera ; (prthos, straight; pteron, wing,)
embraces the Crickets, (Achetina^) Grasshoppers, (Gryl-
lina,) (Fig. 138,) Locusts, (Locustina,) and Cockroaches,

FIG. 138.— i. Dragon-fly, (Libellulina dejressa.) 2. Grasshopper, (Gryllus.) 3. Bee,
(Afzs mellijica.) 4. Fly, (Musca domestica.) 5. Butterfly, (Pontia brassica.) 6. Musk-
beetle, {Cerambyx moschatus.)

(Blattina.} . Mouth masticatory. Wings four, or want-
ing ; anterior pair small, thickened, and overlapping
along the back ; the hinder pair broad, net-veined, and
folding like a fan. Legs various, being powerful jump-
ing organs in grasshoppers, raptorial (raptor, a plun-
derer) in Mantis ; cursorial (ciirro, to run) in Locusts.
Each family produces sounds which are characteristic,
and which are supposed to be produced by the rapid
friction of the long hind legs against the wing. The
sound of the Grasshopper is said to be the highest
known musical note.

ARTICULATA. 235

Order 3. Hemiptera, (hemi, half; pteron, wing,) have a
suctorial mouth, produced into a long, hard beak. The
four wings are irregular and sparsely veined, or wanting.
The body is flat above, and the legs slender. In some
the four wings are opaque at the base, and transparent
at the apex, whence the name of the order. Some feed
on the juices of animals, and some on plants. Plant-lice,
(Aphides?) the wingless Bed-bug, (Cimex^) and Louse,
(Pediculus?) the Squash-bug, (Coreus,) Water-boatman,
(Notonecta^) Seventeen-year Locust, (Cicada^) and the
Cochineal, (Coccus?) are examples.

Order 4. Coleoptera. (Koleos, a sheath ; pteron, wing.)
This is the largest of the orders, containing about ninety
thousand species. The thickened, horny fore-wings, or
elytra, (elytron, a sheath,) are not used for flight, but to
cover the hind pair. When at rest the elytra are united
by a straight edge along their length, and the hind wings
are folded transversely. The mouth is armed with for-
midable mandibles; the integument is generally hard,
and the legs are strong. The larvae are worm-like, and
the pupa is motionless. The highest tribes are carniv-
orous. Among them we find the Tiger-beetles, (Cicin-
delal) the common Ground-beetles, (Carabus^) whose hind
wings are often absent, the Diving-beetles, (Dytiscus^)
with boat-like body and oar-like hind legs, the Carrion-
beetles, (Silpha^) with black, flat bodies and club-shaped
antennae, the Goliath-beetles, (Scarabceus,) the Snap-
ping-bugs, (Elata?) the Lightning-bugs, (Pyrophorus?)
the spotted Lady-birds, (Coccinella^) the Long-horned
beetles, (Cerambycidce?) and the destructive Weevils,
(Curculionidce^) with pointed snouts. (Fig. 138.)

236 THE SCIENCE OF LIFE.

Order 5. Diptera, or two- winged Flies; have the hinder
pair of wings replaced by " poisers/' or "halteres" A
few species are wingless. The eyes are large, with many
facets ; the tongue terminates in a fleshy knob, and the
rest of the mouth is suctorial, and furnished with fine
lancets ; the thorax is globular, and the legs slender.
The larvae are footless grubs. Among them are House-
flies, (Musccz?) (Fig. 138,) Gnats, (Culicidce^) Crane-flies,
( Tipulida, ) Forest-flies, ( Hippoboscce, ) and Gad-flies,
(Gabrinufo!) The wingless Flea (Pulex) is also placed
in this order.

Order 6. Lepidoptera, (lepis, scale ; ptcron, wing,) in-
cludes Butterflies and Moths. They have four large
wings, thickly covered on both sides with minute over-
lapping scales, of different colors, and often arranged in
patterns of exquisite beauty. These scales are epider-
mic appendages of a similar nature to hairs, and every
family has a special form of scale. The head is small,
the body is cylindrical, and the legs are little fitted for
locomotion. The mouth is a proboscis, or coiled tube,
sometimes an inch long. The caterpillar, or larva, has a
worm-like form, and from one to five pairs of abdominal
legs, in addition to the six on the thorax. The mouth
is formed for mastication.

There are three groups : the gay Butterflies, (Fig.
138,) having knobbed or hooked antennae, flying in the
sunshine only, and keeping their wings vertical when at
rest ; the dull-colored Sphynges, or evening Moths, with
antennae thickened at the middle, and flying at twilight ;
and the nocturnal Moths, whose antennae are thread-
like and often feathery, and which prefer the night.

ARTICULATA. 237

The pupa of Butterflies is unprotected, and is generally
suspended by a silken thread. The pupa-case is gen-
erally ornamented with golden spots, hence the com-
mon name, chrysalis. The pupa of Moths is inclosed
in cocoons.

Order 7. Hymenoptera, (hymen, membrane; pteron^
wing,) includes Bees, (Fig. 138,) Wasps, Ichneumons,
Saw-flies, and Ants. The mouth is fitted for both biting
and suction ; the legs are for locomotion as well as sup-
port ; and the four membraneous wings are equally trans-
parent, and interlock by small hooks during flight. The
females are usually provided with a sting, or borer. The
larvae are footless, helpless grubs, generally nurtured in
cells, or nests.

The colony of Bees is formed of the perfect female,
called the " Queen-bee," many perfect males, or drones,
and a swarm of sexless bees, the neuters, or workers.
The drones and the neuters are produced by partheno-
genesis. (Chap. Ill, Sec. 16.)

The "vespiary" of the Wasps, like the hive of the
Honey-bee, contains males, females, and neuters ; but
the perfect males work equally with the neuters.

Ants (Formicidce) also form colonies, and the observa-
tions made upon many species show a wonderful amount
of intelligence in these creatures. In many ant-colonies
the neuters consist of two classes — " the workers," who
do all the building and storing of the little town, and
" the soldiers," who defend the works. Their treatment
of Plant-lice, or Aphides — keeping them, and milking
them as men do cows — their slave-capturing expeditions,
and the recently-discovered agricultural ant-colonies,

238 THE SCIENCE OF LIFE.

furnish abundant food for the propensity to the mar-
velous in human nature, and prove to the philosophic
observer of creation how closely related are all living
things to properties of thought, affection, and will,
which are generally regarded as spiritual ratLer than
material.

VERTEBRATA. 239

CHAPTER XV.

VERTEBRATA.

Thus the seer,

With vision clear,

Sees forms appear and disappear,

In the perpetual round of strange

Mysterious change

From birth to death, from death to birth,

From earth to heaven, from heaven to earth ;

Till glimpses more sublime

Of things unseen before,

Unto his wondering eyes reveal

The Universe, as an immeasurable wheel

Turning for evermore

In the rapid and rushing river of Time.

— LONGFELLO \V.

i. THE type, or sub-kingdom, Vertebrata, (vertebra, a
joint of the back, from vertere, to turn,) is characterized
by the separation of the greater part of the nervous sys-
tem from the general cavity of the body. A transverse
section of the body exhibits two cavities, or tubes ; the
dorsal, or neural, tube, containing the cerebro-spinal
nervous system, and the ventral, or haemal tube, inclos-
ing the alimentary canal, heart, lungs, and a double chain
of ganglia belonging to the sympathetic system of nerves.
The ventral cavity, with its contents, corresponds to the
whole body of an Invertebrate animal, while the dorsal
tube is distinctly typical.*

Vertebrates have an internal, jointed skeleton, capable

* See Frontispiece.

240

THE SCIENCE OF LIFE.

of growth and repair. (Chap. IV, Sec. 13, d.) During
embryonic life it is represented by the notochord, a fibro-
cellular rod, tapering to either end, but this is replaced
by a more highly developed column of cartilage or bone,
except in the doubtful Amphioxus. The column and
cranium are never absent, although other parts may be
wanting, as the ribs in Frogs, limbs in Snakes, etc. The
limbs never exceed four, and when present, are always
articulated to the internal skeleton, on the ventral side
of the body, while the limbs of Invertebrates are devel-
oped from an external skeleton, on the neural side. The

FIG. 139. — Muscular Fibers. Magnified 200 diameters.

muscles moving the limbs are attached to the endoskel-
eton and not to the exoskeleton, as in Invertebrates.
Muscular tissue is found in all animals, from Radiates to
Man. The most complete development of muscles is in
the Pentacrinus. (Chap. XII, Sec. 5.) Voluntary mus-
cular tissue always has a transversely striated appearance
under the microscope, (Fig. 139,) while those fibers not
under the control of the will are smooth.

41

VERTEBRATA. 2

.

The circulation of the blood is complete in Vertebrates,
the arteries being joined to the veins by capillaries, so
that the blood never escapes into the visceral cavity, as
in the Invertebrates. All have a portal vein, carrying
blood through the liver, and all have lacteals and lym-
phatics. The blood is red, and contains both red and
white corpuscles. The teeth are developed from the
dermis, never from the cuticle, as in Mollusks and Artic-
ulates ; the jaws move vertically, and are never modified
limbs. The liver and kidneys are always present. The
respiratory organs are either gills or lungs, or both.
Vertebrates are the only animals which breathe through
the mouth.

The arrangement of the circulatory system varies i:i
the different classes, in accordance with
the structure of the respiratory organs.
In Fishes (Fig. 140) the heart is double
as in the Oyster, but instead of drivh\
arterial blood over the body, it receive.;
the returning, or venous blood, and sends
it to the gills. From the capillaries of
the gills the blood is passed into a large
artery, or aorta, along the back, which
distributes it by a complex net-work of
capillaries among the tissues. These cap-
illaries unite with the ends of the veins
which pass the blood into the auricle of

the heart, after purification in the liver ";Auri<;le- ^-Ventri-
cle, c. Pulmonary Ar-

and kidneys. tefy- e- Pulmonary

Veins, bringing blood

In Amphibia and Reptiles (Fig. 141) from the giiis, </, and

uniting in the Aorta,

the heart has three cavities; two auricles /. s.
£1

242

THE SCIENCE OF LIFE.

and one ventricle. The venous blood from the body is
received into the right auricle and the purified blood

from the lungs into the
left. Both communi-
cate with the ventricle,
which pumps the mixed
blood part to the lungs
and part around the
system.

The highest form of
circulation is seen in
the warm-blooded Ver-
tebrates, Birds, and
Mammals. The heart

FK;. 141. — A. Plan of Circulation in Amphibia

and Reptiles. B. Plan of Circulation in Birds and has foUT CaVltlCS 3.

Mammals, a. Right Auricle receiving venous blood

from tbe system, b. Left Auricle receiving arterial Tight aild left auricle,

blood from the lungs, c. c' . Ventricles, d. e.f. Sys- , . 1 j i r

temic Artery, Vein, and Capillaries, g. h. k. Pul- and a ngftt and left

monary Artery, Vein, and Capillaries. ventricle. The right

auricle receives the blood from the veins, transmits it to
the right ventricle, which sends it to the lungs. The
left auricle receives it from the lungs, and sends it to the
left ventricle, which propels it over the body. The two
auricles contract together, and so also do the ventricles,
making certain faint sounds, which may be imitated by
the words lubb tup. (Fig. 141.)

The greatest differences between Vertebrates and other
animals are found in the Nervous system, which, as we
have seen, has a distinct tube or cavity in this type, al-
together unlike the plan of structure elsewhere.

In living things, like the Protozoa, or Protophytes,
which are composed of a simple mass of bioplasm, all

VERTEBRATA. 243

the functions necessary for animal or vegetable life belong
equally to every atom of the mass. In Chap. V, Sec. 7,
it was shown that the simplest plants and animals differ
from the highest, or more complex, only in the modi-
fication of some parts of the structure to serve special
functions. Thus locomotion is served by the change of
bioplasm into muscle, or bone, external protection by
transformed epidermal bioplasm, as described in Chap.
IV. To regulate and harmonize the complex organs of
digestion, respiration, circulation, and secretion, and to
conduct sensation and motor force, seems to have been
the object of the change of bioplasm into nervous matter.

Nerve matter exists in the form of cells and of fibers.
The cells are soft and grayish, and are generally found
accumulated in masses or ganglia, sometimes called
nerve-centers. The fibers are of two kinds, one soft and
nucleated, the ganglionic or sympathetic fibers, and or-
dinary nerve-fibers.

These latter are for a great part of their length in-
closed in a transparent sheath, which coagulates after
death into a white substance — the white substance of
Schwann. A number of these fibers, thus ensheathed,
are bound in bundles, which are called nerves. Some of
these fibers proceed or conduct impressions from the
surface, or from the different organs where they are
found, toward the gray centers only, and are called af-
ferent or sensory nerves. Others conduct an influence
from the centers to contract or move the muscles, and
are called efferent, or motor nerves. Thus, on receiving
any impression, as the prick of a pin, an afferent nerve
conducts the impression to the center, from which an

244 THE SCIENCE OF LIFE.

efferent nerve conducts power for the muscles to contract.
If the afferent nerve of a part is cut across or injured,
sensation is lost, but motion remains ; but if the efferent
nerve is cut, the power of motion is lost while sensibility
continues. This form of nerve-action is called reflex.
Many actions of this sort are wholly involuntary, as the
motions of the limbs in paralytics excited by tickling the
soles of the feet.

In the Star-fish we find a nervous ring around the
mouth, made of five ganglia, with radiating nerves, cor-
responding with the type of structure. The Mollusks
have an irregularly scattered nervous system, consisting
of two or more ganglia around the gullet and one or two
more in the posterior region, united by threads, and
sending fibers to various organs. The Articulates have
generally a double nervous cord along the ventral side,
studded with ganglia of nearly uniform size, except the
first, which is largest. In the higher forms, as the Bee,
several ganglia are fused together in the head and tho-
rax, indicating a concentration of organs for sensation
and locomotion.

The nervous system of the Invertebrates is Jiomolog-
ically represented by the ganglionic or sympathetic sys-
tem of Vertebrates, which supplies the unstriped or in-
voluntary muscles, and presides over organic or visceral
functions, such as digestion and circulation. In addition
to the sympathetic system, Vertebrates have a brain and
spinal cord, forming the cerebro-spinal system, (Fig. 142,)
to which there is nothing similar in other animals, and
which presides over what are called the functions of ani-
mal or sentient life, as sensation and locomotion. Yet

VERTEBRATA.

245

as many Invertebrates exhibit sensibility and voluntary
actions, it follows that analogically the nervous system
in them represents both the sym-
pathetic and cerebro-spinal systems
of Vertebrates.

The form of the brain differs much
among Vertebrates. In some the
cerebral hemispheres are small ; in
certain Fishes smaller than the optic
lobes ; in the higher tribes they near-
ly or quite overlap both olfactories
and cerebellum. The brain may be
smooth, as in most cold-blooded ani-
mals, or greatly convoluted, as in
Man.

Vertebrates are subdivided into five
classes: Fishes, Amphibians, Reptiles,
Birds, and Mammals. The first three
are cold-blooded, the other two warm-
blooded. Fishes and Amphibians
agree in having gills during all or a
part of their lives. The rest never

have gills. FlG> M*- — Human Brain

and Spinal Cord, one fifth

2. FISHES, (PlSCeS.) These are COn- natural size- «• Great longi-
tudinal fissure, b. Anterior

sidered the lowest of Vertebrates, yet lobe. c. Middle lobe. d. Me

,1 dulla oblongata. e. Cerehcl

they are so numerous as to embrace iura. /. First spinal „««=.
nearly one half of all Vertebrates, tjgSSZ*^

and SO Varied that it is difficult tO salnerves- '.Lumbar nerves

k. Sacral plexus of nerves for

frame a definition which shall include the limbs- l- Cauda equina.

,. The figures indicate the

all. twelve pairs of cranial nerves,

FishesHve in the water and breathe

246

TIIK SCIENCE OF LIFE.

by means of gills. They are generally covered with
scales, and they have fins instead of limbs. They have
large immovable eyes, but no external ears. Both jaws
are movable. The teeth are numerous, and are gener-
ally recurved spines, as in the Pike ; flat and triangular,
with serrated edges, in the Shark ; and tessellated, in the
Ray. The digestive tract is relatively shorter than in
other Vertebrates. The blood is red, and the heart has
two cavities, an auricle and a ventricle, both on the
venous side. Ordinary fishes have four gills, the water
escaping by one external aperture, or "gill-slit;" but in
Sharks there is a separate opening for each gill.

There are four principal varieties of fish-scales. (Fig.
143.) i. Cycloid scales, (cyclos, a circle,) which are most

common ; thin,
flexible, and sil-
very, as in the Sal-
mon. 2. Ctenoid,
(kteiS) a comb,)
with a comb-like
fringe of toothed
processes. 3. Ga-
noid, {ganos,

FIG. 143.— Varieties of Fish Scales. <*. Ctenoid scale, b. Cy- brightness,) gCH-

cioid scale, c. Ganoid scale, d. Placoid scale. erally larger than

the preceding, and having an under layer of bone with
a superficial layer of enamel. Most ganoid fishes are
extinct. 4. Placoid, (plax, a flat plate ;) these are formed
of bony granules, or tubercles, or plates, the plates often
being furnished with spines.

Most fishes have a series of small scales running along

VERTEBRATA. 247

the side of the body, called the lateral line. Each scale
is perforated by a tube which runs along the whole length
of the body, and is connected with cavities in the head
which secrete the mucus for lubricating the scales, and
enabling the fish to move with little resistance.

Order I. PharyngobrancJis, (pharynx, the pharynx, and
bragchia, gills.) This contains but one member, the
Lancelet, (Amphioxus lanceolatus^) which burrows in the
mud of the Mediterranean Sea. It is such an eccentric
creature, without skeleton, limbs, brain, heart, lym-
phatics, or red blood, that it can hardly be considered a
Vertebrate at all. Yet, because it has a persistent noto-
chord, evolutionists have made much ado over it, and it
figures largely in their imaginary Phylogenies. (Chap. Ill,
Sec. 8.)

Order 2. Marsipobranchs, (inarsipos, a pouch.) They
have a cartilaginous skeleton and sac-like gills, but no
scales, limbs, or lower jaw, and only one nasal organ.
They comprise the eel-like Lampreys and Hags. (Fig.
144.) The mouth is round and sucker-like ; and in the

FIG. 144.— Lamprey.

Hags (Myxince) contains a single large recurved, serrated
fang for piercing the bodies of their prey. Respiration is

248

THE SCIENCE OF LIFE.

carried on by muscular little pouches (marsiipia) placed
on the sides of the neck.

Order 3. Teleosts, (teleios, perfect ; osteon, a bone,) in-
cludes all the true osseous fishes. The skull is compli-
cated, the upper and lower jaws complete, and the gills
are comb-like, or tufted. The tail is Jiomoccrcctl, having
equal lobes. The other fins vary in number and position.

a

FIG. 145. — Gray Mullet : a. First dorsal fin. b. Second dorsal, c. Pectoral, d. Ventral.
e. Anal. f. Caudal.

In the soft-finnecl Fishes, the ventral fins (Fig. 145) are
absent, as in the Eels ; or attached to the abdomen, as

FIG. 146.— The Cod.

in Salmon, Herring, Pike, and Carp; or placed under the
throat, as in the Cod, (Fig. 146,) Haddock, and Flounder.

VERTEBKATA.

249

In the spring-firmed Fishes, the ventrals are generally
under or in front of the pectorals, and the scales are cte-
noid, as in the Perch, Mullet, and Mackerel.

Order 4. Ganoids include the Sturgeons, (Fig. 147,)

FIG. 147.— The Sturgeon, {Acipenser Sturio.)

Bony-pike, Polypterus, and many extinct forms. The
skeleton is rarely completely ossified ; the ventral fins
are placed far back, and the tail is heterocercal, or une-
qually lobed, from the vertebra continuing in the upper
lobe.

Order 5. Elasmobranchs (clasma, a thin plate) contain
Sharks, Rays, and Chimeras. The gills are formed of
thin laminae, arranged like the leaves of a book. They
have a cartilaginous skeleton, and a harsh skin called
" shagreen." The gill-openings are uncovered, and the
mouth is generally under the head, (except in the Chi-
merae.) The ventral fins are placed far back, the pecto-
rals are large, and in the Rays enormously developed
and the tail is heterocercal.

250 THE SCIENCE OF LIFE.

Order 6. Dipnoi, (dis, twice ; pnce, breath,) comprises
the Mud-fishes (Lepidosircn) of tropical rivers. (Fig. 148.)

FIG. 148. — Lepidosren.

They have eel-like bodies covered with cycloid scales.
Both ventral and pectoral fins are present, but are small
filiform organs, nowise resembling ordinary fins. They
have rudimentary external gills, and internal ones which
communicate with the exterior by a single slit. They
also possess true lungs, which communicate with the
gullet by a tube or trachea. The heart has two auricles
and one ventricle. They are quite Amphibian in struct-
ure, and live long out of the water.

3. CLASS II, AMPHIBIA, (0w//«, . both ; bios, life,) re-
ceives its name from the animals it contains being able
to live both on land and water. They are cold-blooded
Vertebrates which breathe by gills during some part of
their life, but sooner or later possess lungs. Some retain
their gills through the whole of their life, as the Proteus,
Siren, and Axolotl ; others lose their gills after a time,
and breathe by lungs only, as Frogs, Toads, and Newts.
All undergo metamorphoses after leaving the egg, pass-
ing through the " tadpole" state,, in which they resemble
Fishes in their respiration, circulation, and locomotion.

Order i. Urodela, (oura, a tail ; delos, visible,) the tailed
Amphibia. They have a naked skin, and two to four

VERTEBRATA.

251

legs. The aquatic Newts and land Salamanders drop
their gills, and always have four limbs.

Order 2. Labyrinthodontia (labyrintkos, a labyrinth,
odous, a tooth) are now all extinct. They resembled gi-
gantic Salamanders, except in their complex teeth and
exoskeleton of bony plates.

Order 3. GymnopJiiona, (gymnos, naked ; ophis, a snake,)
also called Cecilia. They have neither tail nor limbs, a
snake-like form, minute scales in the skin, and numerous
ribs.

Order 4. Batrachia, or Anoura. (Fig. 149.) (Batrachos,
frog ; ana, without ; oura, a tail.) These are tailless

FIG. 149. — i. Frog, (Rana temporaria.) 2. Toad, (Bufo vulgaris?) 3. Tadpoles.

Amphibia, and comprise Frogs and Toads. They have
a naked, moist skin, ten vertebrae, and no ribs. They
have four limbs, the hinder longer than the fore-legs.
They have four ringers and five toes. The tongue is
long, fixed at the anterior, and doubled up. It can be
thrown out rapidly as an organ of prehension. The eggs
are laid in the water, enveloped in a glairy mass, and the

252 THE SCIENCE OF LIFE.

tadpoles are like the Urodelans till the gill and tail arc
absorbed. Frogs (Rand) have teeth in the upper jaw,
and webbed feet. Toads (Bufd) have neither teeth nor
webbed feet.

4. Class III. REPTILIA, or Reptiles. These are air-
breathing, cold-blooded Vertebrates, differing from
Fishes and Amphibians by never having gills, and from
Birds by being covered with horny scales, or bony plates.
The skeleton is ossified, and never cartilaginous. Most
are carnivorous, and teeth are present, except in Turtles,
where a horny sheath covers the jaws. The lungs are
imperfectly cellular, and the heart is three-chambered,
containing two auricles and one ventricle, which is some-
times divided by a partition. In all cases a mixture of
arterial and venous blood is circulated. The limbs, when
present, have three or more fingers as well as toes.

There are four orders of living and five of extinct
Reptiles. The living orders are Snakes, Lizards, Tur-
tles, and Crocodiles.

i.) Opliidia, or Snakes. (Fig. 150.) These have no
visible limbs, but a vast number of vertebrae. The Py-
thon has two hundred and ninety-one, the Rattlesnake
one hundred and ninety-four, and the Boa Constrictor
three hundred and five. They have immovable trans-
parent eyelids. The tongue is bifid (cleft) and extensile.
The mouth is very dilatable, from the number of joints
in the lower jaw united only by ligament. The skin is
shed in one piece by reversing it. Snakes move well
either on land or in water.

Poisonous snakes, as Vipers and Rattlesnakes, usually
have a triangular head covered with small scales, a con-

VERTEBRATA.

253

striction, or neck, behind the head, two or more fangs and
few teeth, small eyes with vertical pupil, and short, thick

FIG. 150.— i. Rock Snake, (Python molurus^ 2. Spectacled Snake, (Cobra de Cap-
fllo. 3. Boa Constrictor.

tail. In the harmless Snakes the head blends with the
neck, and is covered with plates, (Fig. 151,) the teeth
are numerous in both jaws, the pupil is round, and the
tail tapering.

2.) Lacertilia, comprising Chameleons, Blindworms,
and Lizards, are distinguished from the other orders by
possessing clavicles, and having teeth not lodged in sock-
ets, as in the Crocodiles. They are often like Snakes
with four limbs, each having five digits. Some have no

exoskeleton, but it is generally present in the shape of

22

254

THE SCIENCE OF LIFE.

scales, or horny plates, or spines. In the Iguanidce it is
elevated into a crest, or mane, of horny scales, covering
also the throat-pouches. The Draco volans, or Flying
Lizard, has a cutaneous expansion from the false ribs
which enable it to take short flights through the air.

FIG. 151. — A. Head of Harmless Snake. 1). Heads of Poisonous Snakes of different
genera.

The tongue is bifid in many of this order, but in Cha-
meleons it is a long, round, muscular organ, clubbed at
the end, and coated with a viscid secretion, by means of
which it catches great numbers of flies by shooting it
out with remarkable speed.

3. Chelonia, or Tortoises and Turtles. These resemble
Amphibians in some respects, but their structure is very
peculiar. The exoskeleton unites with the endoskeleton,
forming the carapace, or case, which includes the viscera
and muscular system. The vertebrae are soldered to-
gether and the ribs are expanded, making the walls of
the carapace. The ventral piece is called the plastrom,
or sternum. (Fig. 152.)

VERTEBRATA. 255

The Sea-turtles, as the edible Green Turtle and the
Hawk's-bill Turtle, which furnishes the tortoise-shell of
commerce, have the limbs formed for paddles. The
fresh-water forms, as the Snapping Turtle, (Chelydra^)

FIG 152.— Skeleton of Turtle.

are amphibious, and have palmated feet. Land Tor-
toises (Testudo) have short, clumsy limbs, fitted for slow
motion on land.

4. Crocodilia, or Crocodiles, Alligators, and Gavials.
(Fig. 153.) These are the largest Reptiles. They have
a double exoskeleton, one of horny scales, (epidermic,)
and another of bony plates, (dermal.) The bones of the
skull are united by sutures, and the jaws are furnished
with numerous teeth implanted in distinct sockets.
Crocodiles can be distinguished from Alligators by the
fourth tooth on the lower jaw being larger than the rest,
and by its projecting on each side of the snout. The
toes of Gavials and Crocodiles are fully webbed, but
those of Alligators are only half- webbed. Some Croco-
diles in the Nile attain to a length of twenty-five feet.

256

THE SCIENCE OF LIFE.

The Gavials, or Crocodiles of the Ganges, have the jaws
produced to an enormous length.

5. CLASS IV. AVES, or Birds, are warm-blooded Ver-
tebrates, clothed with feathers.

The bones of Birds are very compact and ivory-like,
yet lighter than those of Reptiles or Mammals. Many

FIG. 153. — i. Crocodile, {Crocodilus vulgaris^ 2. Alligator, {Alligator lucius.)
3. Lizards.

parts of the skeleton are fused, or anchylosed together.
The lumbar vertebrae are wanting, but the neck con-
tains from nine to twenty-four vertebrae, rendering it
quite flexible. The sternum is strong, and in birds of

VERTEBRATA. 257

flight possesses a median Keel, (carina^) to afford an
increase of space for attachment of the great pectoral
muscles. Hence these birds are called carinatce. The
skull articulates with the spine by a single condyle, and
with the lower jaw by the intervention of a separate
bone, as in Reptiles.

The beak is the bird's principal organ of prehension,
and differs in shape according to habits and food. The
pharynx is simple. The oesophagus varies in different
orders. Except in some aquatic birds, the food is re-
ceived first into a temporary stomach, or crop, which is
largest in grain-feeders. From this the oesophagus leads
to the true digestive stomach, which secretes the gastric
juice, (proventricidusl) and leads to the muscular stom-
ach or gizzard, (yentriculus bulbosus.)

In tlesh-feeders this is thin, but in grain-feeders it is a
powerful triturating organ. The small intestine is short
in carnivorous birds and long in others. The large in-
testine ends in a dilated sac, the cloaca, which also re-
ceives the terminations of the urinary and generative
organs.

The trachea is furnished with two larynges ; one at
the upper part, as is usual in animals, and one called the
syrinx, which is the principal organ of voice, at the bi-
furcation of the trachea into the two bronchi. Every
means are employed to render the respiration rapid and
complete. The lungs are large and cellular, and the
bronchial tubes not only divide continuously in them,
but conduct air into the general cavity of the abdomen
and to the interior of many of the bones.

The feathers of birds are cutaneous growths, each

0¥ TEB

'UHIVE?

258

THE SCIENCE OF LIFE.

formed on a vascular papilla at the bottom of a pit, or
follicle. They are composed, like hair, of epithelial cells.
Each feather consists of a quill, or barrel, and a vane, or
beard, which is composed of barbs and barbules. The

FIG. 154.— A. Ear coverts. B. Bastard wing. C. D. E. Wing coverts. F. Primaries.
G. Scapulars. H. Secondaries. L. Tail coverts.

barbules, from contiguous barbs, hook into each other
like the latch of a door into its catch, so as to present an
even and resisting surface to the air. Feathers receive
different names on different parts of the bird's body.
The feathers clothing the body are called clothing feath-

VERTEBRATA.

259

ers ; the great quill tail feathers, so useful in steering
are the rectrices ; those lying over the humerus and
scapular are the scapulars; the proximal end of the
ulna is covered with the tertiarics ; the distal end of the
same bone with the secondaries ; while the bones of the
hand support the primaries, which are largest of all.
Each quill often carries a little light feather just beneath
the commencement of the vane, the accessory plume, or
plumule. These form the greater, lesser, and under
wing coverts. (Fig. 154.)

Order I. Natatorcs, or Swimmers. These have the
body boat-shaped, and the feet more or less webbed.

One division of swimming birds is called Brevipinnata,
(Short-wings,) the feathers and wings being short. It

FIG. 155. — Common Tern.

includes the Penguins, Grebes, Puffins, Guillemots, and
Divers. In the Penguins the wings are too short for

260

THE SCIENCE OF LIFE.

flight. The legs are placed far back, and the wings
assist the webbed feet as paddles.

The Cormorants, Pelicans, Gulls, Petrels, and Terns
(Fig. 155) form the group of Longipinnatce, or Long-
wings. The beak is hooked and pointed, the tip being
often very hard. The Albatross, one of the largest and
most beautiful birds of flight, belongs to this group.

The Lamellirostres, or Flat-bills, form a third division,
including Ducks, (Fig. 156,) Geese, Swans, and Flamin-

t

FIG. 156.— Wild Duck, (Anas l>oschas.) North America.

goes, whose bills are horizontally compressed, coverec
with a soft cuticle supplied with twigs from the fifth
nerve, and have fringed sides, which strain the muddy
food.

Order 2. Grallatores, or Waders, (grallce, stilts,) have
long, stilt-like legs, toes free, wings large and powerful.

VERTEBRATA.

261

The Rails, Coots, Water-hens, and Jacanas form a
group called Macrodactylce, because the claws are very
long. They are four in number, and lobed. The beak
is somewhat cuneiform, and the tail is very short.

The Cultirostres, with elongated forcep-like bills for
fishing, include the Cranes, Herons, (Fig. 157,) Stilts,

FIG. 157. — Heron.

Ibis, and Spoonbills. The legs are very long, and not
covered with feathers.

The Longirostres, or Long-beaks, possess long and
sensitive beaks, grooved by nostrils. The legs are of
moderate length. They are insectivorous. The group
comprises the Snipes, Woodcocks, Sandpipers, Curlews,
Ruffs, and Godwits.

The Plovers, Lapwings, Bustards, Longshanks, and
Oyster-catchers form the Pressirostres. All possess a

262 THE SCIENCE OF LIFE.

moderate bill with a compressed tip. Feet semi-pal-
mate, wings long and strong.

Order 3. Cursores, or Runners. The wings are rudi-
mentary and unfit for flight. The legs are hollow,
strong, and long. The order includes the Ostriches,
Cassowaries, and Apteryx, marked by their large size,
keelless breastbone, and robust legs. The African Os-
trich has two toes, the Cassowary three, and the Ap-
teryx four. The barbs of the feathers are disconnected,
forming plumes.

Order 4. Rasorcs, or Gallinac.ece, Scratchers, or Fowls.
(Fig. 158.) These have a short arched bill, and short

FIG. 158.— Turkey, (Meleagris Gallopavo.)

and concave wings. There are three anterior toes and
one posterior. The anterior are blunt and adapted to
scratching. The gizzard is very strong. The legs are
usually feathered to the heel, and sometimes to the
toes. The males have usually gay plumage and some

VERTEBRATA

263

appendage to the head. Their principal food is grain.
The order comprises the common Fowl, Turkey, Par-
tridge, Grouse, Pheasant, Ptarmigan, and Pea-fowl.

The preceding orders form a legion called Autopliagi,
since immediately on being hatched they can run about
and look after themselves. The remaining orders form
the legion Heterophagi, in which the young are depend-
ent upon their mother for nourishment for some time
after birth.

Order 5. Columbce, or Pigeons. These differ from the
Scratchers in possessing powerful wings. They have
slender legs, with toes ununited, and the hind toe on a

P'iG. 159.— Wood-Pigeun.

level with the rest. Pigeons, Doves, (Fig. 159,) and the
extinct Dodo are found in this order.

Pigeons exhibit in a great degree the mutability of
races or varieties ; all the vast number of Pigeons,

264 THE SCIENCE or LIFE.

Carriers, Tumblers, and Fantails, being descended fioin
one common stock — the blue rock Pigeon, Colmnba
livia.

Order 6, Scansores, or Climbers, have four toes, two
directed forward and two backward. They feed on in
sects or fruit. They are not usually musical. The
majority make nests in the hollows of old trees, but the
Cuckoos lay in the nests of other birds. In climbing,
the Woodpeckers arc aided by their stiff tail, and the
Parrots by their hooked bill. Cuckoos, Parrots, Toucans,
Trogons, Woodpeckers, and Wrynecks belong to this
order.

Order 7. ftissrn's, or Perchcrs, is the most numerous
of all the orders. The t\vo outer toes are joined by
membrane. Of the two others, one is always directed
backward. Females are generally smaller than males,
and have more somber colors. Their nests arc often 01
beautiful construction. The voice is often musical, the
plumage lustrous, and the power of flight perfect.

The ConirostrcSy (Cone-bills,) with a short, strong,
roundish or conical beak, which tapers rapidly from a
broad base to a short tip, includes the Finches, with the
Sparrows, Larks, Crossbills, Crows, and Hornbills. Birds
of Paradise, also, and many migratory birds, as the Star-
ling, belong here.

The Shrikes, Fly-catchers, Nightingales, Orioles, Rob-
ins, Thrushes, Tits, and Warblers form another group,
the Dcntirostrcs, or notched-beaks, from having an ab-
rupt notch on the margin of the upper beak, near its
tip.

The Humming-birds, Hoopoes, Wrens, Creepers, and

VERTEBRATA. 265

Honey- eaters, constitute the Tennirostres, (Slender-
beaks,) in which group the beak is elongated into a
slender forceps for extracting honey or insects from the
deep parts of flowers. The plumage is often of a gor-
geous metallic luster.

The Swallows, (Fig. 160,) Martins, Goatsuckers, King-
fishers, and Swifts, make up the Fissirostrcs, (Cleft-beaks,)

FIG. 1 60.— Swallow, (Hirundo.}

with a wide but short beak. During flight the mouth is
kept wide open, and any insects it encounters are re-
tained by a viscid secretion. A young Swallow will in
this way consume over a thousand flies and gnats in a
day.

Order 8. Raptores, or Raveners. These are readily
recognized by their beak, which is a formidable weapon
with sharp edges and an acute hooked tip. The upper
bill overlaps the lower. The toes are three in front

and one behind, all terminated by sharp hooked talons.
23

266

THE SCIENCE OF LIFE.

Wings, very large and powerful. Legs, short, stout, and
strong.

^f

•O
-

FIG. 161.— Golden Eagle.

There are two
sections: theDiur-
nal, whose bright
eyes are on the
^f> sides of the head,
wings pointed, and
metatarsus and
\ toes covered with
scales, as Vultures,
Kites, Hawks, Fal-
cons, and Eagles,
(Fig. 161 ;) and the
Nocturnal, whose
large eyes are di-
rected forward, and surrounded with radiating feathers,
metatarsus feathered, plumage soft, as Owls. (Fig. 162.)

FIG. 162.— Barn Owl.

VERTEBRATA. .267

6. CLASS V. MAMMALIA, or Mammals. These are warm-
blooded Vertebrates possessed of mammary glands. They
suckle their young. The thorax and abdomen are sepa-
rated by a diaphragm, the red corpuscles of the blood
are doubly concave and round, (except in the Camel and
the Llama,) and either a part or all of the body is hairy.

All Mammals use their lips for prehension, which are
assisted in some orders by their fore-limbs. The Car-
nivora tear their prey with their claws, but do not use
them as prehensile organs. The proboscis of the Ele-
phant, the snout of the Tapir, the long viscid tongue of
the Ant-eater, and the long tongue of the Giraffe, are
special prehensile organs.

The teeth of Mammalia differ in the different orders,
as to number, size, and shape. The true Ant-eater has
no teeth, the Narwhal has but two, one of which is rudi-
mentary, but the Dolphin has one hundred and ninety.
The Whalebone-whale (Balcena mysticetus) has, instead
of true teeth, a series of plates of whalebone ranged in
rows along the upper jaw. From these plates a long
fringe of whalebone threads hangs down, which acts as a
sieve in straining the water from the myriads of little
mollusca which constitute the chief food of the whale.

There are three distinct types of stomach among
Mammals : the simple, the compound, and the complex
stomach. The simple stomach is a single cavity lined
by epithelium, which secretes gastric juice. The com-
pound stomach has the cavity divided by folds into two
or more spaces. The tissue-elements, however, are the
same throughout. The complex stomach is peculiar to
the Ruminants. It consists of four cavities: the paunch

268 THE SCIENCE OF LIFE.

— which is the largest cavity of all — to store the food and
mix it with the water it contains, and which in Camels,
Llamas, and Dromedaries contains pits closed by mus-
cular rims for storing up fluid when the animal is going
a long arid journey ; the reticulum, or honey-comb apart-
ment, where the food is made into small round pellets,
to be regurgitated into the mouth, where they undergo
a second mastication ; the manyplies, with its mucous
membrane arranged in parallel folds, like the leaves of a
book, and where some digestion of soluble parts of the
food may occur ; and the rennet, or true digestive stom-
ach, where the albuminous principles of the food are
extracted and absorbed by the veins.

The digestive canal is much longer in herbivorous than
in carnivorous Mammals, being thirty times the length
of the animal in the sheep, and five times the length in
the cat and dog.

An external ear is rarely absent ; the eyes are always
present, though rudimentary in some burrowing animals;
and, while in all other animals the embryo is developed
from the nourishment contained in the egg, in Mammals
it derives its support, almost from the beginning, direct-
ly from the parent, and, after birth, is sustained for a
time by the milk secreted by the mammary glands.

Order I. Monotremata. Includes two singular forms,
the Duck-mole, (Ornithorhynchusl) arid Spiny Ant-eater,
(Echidna?) both confined to Australia. The former has
a fur covering, a bill like a Duck, and webbed feet. The
latter is covered with spines, has a long, toothless snout,
like the Ant-eaters, and the feet are not webbed. Both
burrow, and feed upon insects.

VERTEBRATA.

269

Order 2. Marsupiala, (marsupos, a pouch,) comprises
Kangaroos, Phalangers, Wombats, and Opossums, (Fig.
163.) Except the latter, all are restricted to Australia

FIG. 163. — Virginian Opossum.

and adjacent islands. The young are always born pre-
maturely, and are transferred by the mother to a
pouch on the abdomen, where they are attached to the
nipples, and the milk is forced into their mouths by
special muscles.

Order 3. Edentata, (toothless.) This order contains
very diverse forms, as the leaf-eating Sloths and the in-
sectivorous Ant-eaters and Armadillos (Fig. 164) of South
America, and the Pangolin and Orycteropus of the Old
World. The gigantic fossils Megatherium and Glypto-
don belong here. The Sloths and Ant-eaters are cov-
ered with coarse hair; the Armadillos and Pangolins with
an armor of plates, or scales. The Ant-eaters and Pan-
golins are strictly edentate, or toothless ; the rest have
23*

2/0

THE SCIENCE OF LIFE.

molars, sometimes very numerous, wanting, however,
enamel and roots.

I IG. 164. — Armadillo.

Order 4. Rodent ia, (gnawers.) These have two long
curved incisors in each jaw, which serve for gnawing the
bark of trees, or other substances on which the Rodent
feeds. The front only is covered with enamel, and the

rest of the tooth is
composed of softer
dentine, which,
wearing faster than
enamel, leaves a
chisel-like edge to
the tooth. Canine
teeth are wanting,

FIG. i6S.-skuii of Rodent. and the flat molars

are separated from the incisors by a wide interval. (Fig.
165.) The hind legs of many Rodents, as the Hare and
Jerboa, are much longer and stronger than the fore-legs.
Most of the order are small in size, except the Capy-

VERTEBRATA. 271

bara, Beaver, and Porcupine. The order also contains
Squirrels, Rats, Mice, and Agoutis. The Beaver has a
smooth, unconvoluted brain, yet shows great ingenuity
in constructing its dwelling, felling logs with its teeth,
building them into a dam, and arranging others as a
shelter, plastering them with mud made into mortar by
its flat, trowel-like tail. The Flying-squirrel (Pteromys)
possesses a cloak of skin, stretching between the fore and
hind limbs, enabling it to sustain short flights in the air.

Order 5. Insectivora, (insect-eating.) These are di-
minutive animals, as the Shrew, the Hedgehog, and the
Mole. They have incisor, canine, and molar teeth, and
the latter have numerous pointed cusps. They have a
long muzzle, short legs, and clavicles. The feet are
formed for walking or grasping, and are plantigrade,
five-toed, and clawed. The Hedgehogs have a spiny
exoskeleton, covering the entire body, and lined by a
broad muscle, which, when it contracts, rolls the animal
into a ball.

Order 6. Cheiroptera, (cheir, a hand ; pteron, a wing,)
are distinguished by long fore-limbs, adapted for flight,
the fingers being very long, and united by a membra-
neous web. The toes and one or two of the fingers are
armed with hooked nails. The Bat may be called the
only true flying Mammal, since it is capable of rapid
and long-continued flights. (Fig. 166.) The Vampire-
bat has a curious leaf-like expansion of the skin cover-
ing the nose. The ears of Bats are very large, and
copiously supplied with nerves of touch. The sense of
hearing is also acute.

Order 7. Cetacea, (Ketos, a whale,) are fish-like in form

272 THE SCIENCE OF LIFE.

and habits. They are the largest of all living forms,
and, next to the Elephant, have the heaviest brains.

FIG. 166.— The Skeleton of Bat. cl. Clavicle, h. Humerus. cu. Ulna. c. Radius.
ca. Carpus. j>o. Thumb, -me. Metacarpus, ph. Phalanges, o. Scapula, f. Femur.
ti. Tibia.

The nostrils are on the top of the head, and constitute
the blow holes, or spiracles. This order includes the
Whales and Dolphins. All have a large horizontally
flattened caudal fin. The head is large, often forming
half the bulk of the animal. The Whalebone Whales
(BalcsnidcB) are toothless, but in the Greenland Whale,
the largest of the group, which sometimes attains a
length of sixty or seventy feet, we find rudimentary
teeth in the embryo. The Toothed Whales (Odontoceti)
have many conical teeth in the lower jaw. The Sperm
Whales are in this division. In them the head is large
and abruptly truncated, and the nostrils are at the end
of the muzzle. The Delphinida, comprising the Dol-
phins, Narwhals, and Porpoises have teeth in both jaws.
Many Cetacea have very small organs of smell, and in
the Dolphins and Porpoises they are wanting.

VERTEBRATA. 273

Order 8. Sirenia (seiren, a siren, or Mermaid) are like
the Cetacea in shape, but are herbivorous, and frequent
great rivers and estuaries. They have both a temporary
and permanent set of teeth, a narrow brain, and nostrils
on the top of a large snout. The Dugong and Manatee
are illustrations of this order.

Order 9. Proboscidia include the Elephant, the extinct
Mastodon, the Dinothere, and the Mammoth. There
are no canine teeth, but the incisors are prolonged into
tusks, which in the Elephant grow from the upper jaw,
in the Dinothere from the lower jaw, and in the Masto-
don from both jaws. The nose is prolonged into a long,
flexible, sensitive trunk, which is terminated by a small
prehensile appendage like a finger. Cuvier counted
20,000 distinct muscles in an Elephant's trunk. The
limbs are massive, each with five toes incased in hoofs,
and with a thick pad intervening between the toes and
the ground.

Order 10. Ungulata, or Hoofed Quadrupeds, have
four well-developed limbs, each having not more than
four complete toes, and each toe being incased in a hoof.
The leg is therefore for support and motion, and not for
prehension. They have temporary and permanent sets
of teeth. The Odd-toed Ungulates include the Horse,
the Rhinoceros, and the Tapir. The Horse, which
with the Ass and Zebra, made up the old order of Soli-
dungula, has only a single perfect toe on each foot,
coated with a nail, called a hoof, so that the horse walks
and runs not merely on its toes, but on its nails. The
Rhinoceros has three toes on each foot, and carries one
or two horns on the skin of the nose.

274

THE SCIENCE OF LIFE.

The Tapir has four toes on its fore feet, and three on
its hind feet, a short snout, projecting nasal bones, and
a short tail.

The Even-toed Ungulates — the Hog, Hippopotamus,
and Ruminants — have two or four toes. The Hog and
Hippopotamus have the four kinds of teeth : incisors,
canines, bicuspids, (or premolars,) and molars, and in the

FIG. 167. — Stag.

wild state are vegetarian. The Ruminants have two
toes on each foot, enveloped in hoofs which face each
other by a flat side, so as to appear like a single hoof
split, or cloven. There may be two supplementary
hoofs behind, but they do not usually touch the ground.
All chew the cud and have a complicated stomach.
They have incisors in the lower jaw only, and these are

VERTEBRATA. 275

apparently eight ; but the two outer ones are canines.
With few exceptions, as the Camel, all Ruminants have
horns, which are in pairs. Those of the Deer (Fig. 167)
are solid, bony, and deciduous ; those of the Giraffe
and Antelope are solid, horny, and permanent ; in the
Goat, Sheep, and Ox they are hollow, horny, and per-
manent.

Order II. Carnivora, or Beasts of Prey, have four
long, acute, canine teeth, and there is a gap between
the incisors and canines of the upper jaw for the recep-
tion of the lower canine. There are usually six incisors
in each jaw. The digits always have sharp and pointed
claws. The body is cov-
ered with hair.

The order is divided
according to the pecu-
liarities of the limbs.
(Fig. 168.)

The Pinnigrada com-
prise the Seals and Wal-
ruses. The fore feet are
webbed and form pad-

fir,. 1(^8. — I oe of Lion. a. With the claw

dleS The hind feet are exte»ded. />. c. Without the skin, retracted

and extended.

at the end of the body,

enveloped in the integument, and in action they resem-
ble the screw of a steam-ship. They live on fish.

The Plantigrada have the whole, or nearly the whole,
of the hind foot in the form of a sole, which rests on the
ground. The claws are not retractile ; the ears are small,
and tail short. Bears, Badgers, and Raccoons are well-
known examples.

276

THE SCIENCE OF LIFE.

Digitigrada walk on the tips of the toes, and keep the
heel raised above the ground. It includes the fierce and
powerful Cats, Pole-cats, Ferrets, Weasels, Dogs, Hy-
aenas, Jackals, Otters, etc. The Cats, (Felidce^) embracing
Lions, (Fig. 169,) Tigers, Leopards, Panthers, and Cat;-,

Fir,. j^o.— Skeleton of the Lion, (Fells I.co^ C. Cervical vertebrae. D. Dorsal verte-
bra:. L. Lumbar vertebra. S. Sacral vertebrae. C. d. Caudal vertebrae, a. Scapula.
b. Humerus. c. Ulna. d. Radius, e. Metacarpus and phalanges, f. Ilium, g. Femur.
h. Ischium. /. Patella, k. Tibia. /. Fibula, m. Tarsus, n. Os Calcis. o. Metatarsus
and phalanges.

have retractile claws, and the radius rotates freely on the
ulna. They have also a prickly tongue.

Order 12. Quadrnmana (four-handed) differ from all
other Mammals by having each of their four limbs termi-
nated by hands, in which the thumb is opposable to the
other digits. (Fig. 170.)

The order is subdivided according to the position of
the nostrils, into I. Strepsirhines, or Monkeys with
twisted nostrils, as the Lemurs and Aye-ayes, which

VERTEBRATA. 277

are the lowest of the monkey tribe. 2. Platyrrhines, or
Monkeys with simple sub-terminal nostrils, as the Spider-
monkeys. These are South American, or New- World
monkeys, with prehensile tails. The Howling-monkey
(Mycetes) has a curious modification of the larynx in the
shape of a bony drum attached to the hyoid bone, with
which it produces discordant shrieks. 3. Catarrhines, or

FIG. 170. — Quadrumana. Baboons. — i. Mandrill, (Papio maimon.) 2. Chacma, (Chac-
ma Porcarius.) Monkeys. — 3. Mona, (Cercopithecus mono,.} 4. Howler, (Mycetes.)
5. Spider, (A teles.)

monkeys with oblique nostrils, approximating below,
separating above, as the Gorilla and Chimpanzee. This
division includes the highest, or anthropoid Apes of the

Old World. They are all four-thumbed. The tail is not
24

278

THE SCIENCE OF LIFE.

prehensile, and is often quite rudimentary. The canine
teeth are large. (Fig. 171.) The arms are long; in the
Chimpanzee reaching to the middle of the tibia, when
hanging down.

FIG. 171. — A. Slcull of the Orang-outang. B. Skull of an ndult European.

Order 13. Biwana, (two-handed,) contains but one
genus and one species: Homo, or Man. (Fig. 172.)

Man differs from all animals in being an erect biped.
The vertebrate type, which in all other cases is horizontal,
in him is vertical. No other animal habitually stands
erect ; in no other are the fore-limbs used exclusively for
head purposes, and the hind pair solely for locomotion.
His limbs are parallel to the axis of his body, not per-
pendicular. They are nearly equal in length, but the
arms are always a little shorter than the legs. In the
Apes the arms reach below the knee.

Man only has a finished hand, which is a perfect organ
of touch, and most versatile in movement. The foot is
planted upon the ground by the entire length of the sole.
The Gorilla has an inferior hand and an inferior foot.

VERTEBRATA.

279

The hand is clumsier and
with a shorter thumb than
man's, and the foot is pre-
hensile, and is not applied
flat to the ground.

Man is peculiar in his
dentition. His teeth are
vertical, of nearly uniform
height, and close together.
In every other animal the
incisors and canines are
more or less inclined, the
canines project, and there
are vacant spaces.

Man possesses two mus-
cles (the peroneus tertius
and extensor primi inter -
nodii pollicis) which are not
found in the highest Apes.
The origin of two other
muscles is in Man alto-
gether different from Apes.
(The tibial origin for the
soleus, and the calcaneal
origin for the flexor brevis
digitorum^)

The human skull has a
smooth rounded outline,
elevated in front, and de-
void of crests. The crani-
um greatly predominates

FIG. 172.— The Human Skeleton, a. Skull.
b. b. Vertebral column, or Spine, c. Ribs.
d. Sternum, or Chest bone. e. e. Scapulae,
or Blade bones. f. /. Clavicles, or Collar
bones, g. g. Pelvic, or Hip bones, h, h. Hu-
meri, or Arm bones, z. Radius, and j. Ul-
na, bones of fore-arm, k. Femur, or Thigh
bone. /. Tibia, or Large bone of leg. in. Fib-
ula, or Small bone of leg. n. Calcaneum, or
Heel bone. o. Tarsal bones, or Bones of
the foot. /. Carpal bones, or Bones of the
wrists.

280 THE SCIENCE OF LIFE.

over the face, being four to one. Man differs from all
Apes in the absolute size of brain, and in the greater
complexity and less symmetrical arrangement of its con-
volutions. The brain of the Gorilla scarcely amounts
to one third in volume or one half in weight of that of
Man.

From purely morphological reasons, therefore, Man is
entitled to rank as a distinct order of Vertebrates. Other
considerations, to be referred to in the next chapter,
show that he should be regarded as a distinct type.

THE HUMAN TYPE. 281

CHAPTER XVI.

THE HUMAN T Y P E .

The master-work, the end
Of all yet done ; a creature, who, not prone
And brute as other creatures, but endued
With sanctity of reason, might erect
His stature, and upright with front serene
Govern the rest, self-knowing ; and from thence
Magnanimous, to correspond with Heaven,
But grateful to acknowledge whence his good
Descends; thither with heart, and voice, and eyes
Directed in devotion, to adore
And worship God Supreme, who made him chief
Of all his works.— MILTON.

1. IN the rapid panoramic survey of living forms,
which is all our limits will allow, we have mainly con-
fined ourselves to structural forms, barely glancing at
the instinctive peculiarities which determine these forms
for special ends. It is necessary to supplement our re-
view by a reference to functions and endowments which
the structure itself may not always indicate.

2. Biology includes not only Anatomy and Physiology,
but Psychology also. " The naturalist studies the in-
stincts of the Ants and the Bees. When he attempts
the history of Man, shall he put aside that which in him
represents these instincts ? Evidently not. Consequent-
ly he must not stop with the body. He must consider
the intelligence which is in us, and which, up to a cer-
tain point, we have in common with animals; he must

show that it is this element of our being which recog-
24*

282 THE SCIENCE OF LIFE.

nizes the outer world, which judges, which aspires. His
work will be very imperfect if he neglects this some-
thing of which the nature escapes us, but of which the
power is such, that through it man has not only van-
quished all animals, whatever their defenses, their size,
or their strength, but he has overcome, and made to
work as his servants, even the immutable forces of the
inanimate world." *

3. We have seen that the lower animals partake of
living structures and organs, the same in essential char-
acter and objects as those of man. Careful observation
will show that they also possess many mental or psycho-
logical endowments, such as we find in the human type.
The differences of animated nature are differences of
degree rather than of essential nature. So far as we can
see, all animals have self-consciousness and volition, and
many exhibit unmistakable signs of reason.

4. On page 283 is an outline plan of the psychical en-
dowments of man, with the objects constantly influenc-
ing him and the normal activities of his being. It be-
gins with the most general and elementary properties
of animal life, and rises to the highest special powers
of human nature. More than an outline cannot be at-
tempted, since an elaborate exposition would require a
large volume.

5. It will be seen that we have given prominence to
consciousness in the plan referred to. This is because
it is an essential condition of every mental operation.
It is the knowledge which the mind has of its own
operations.

* Quatrefage's " Natural History of Man."

' y>> 0* TEJ ^X

urivsEsiTy)

c**1 ^**§fjf

THE HUMAN TYPE. 283

Objective. SUBJECT. Subjective.

g-SJS Will.
Spiritual and Rational Ob-

pintual and Rational Ub- £ ^ o Judgment

jects. (the Good, Beauti- .2 g .g JUflgme

ful, True, etc.) g ;| ^ Faith<

— I
I I

| | -f | Fancy.

^ The Mind itself. g S | , ,

k .2 g'Ei) Thought.

^ w'5 2

8

s g.

§ Perception.

•S Objects of Sense. .2 *g '^

.1 § c/3 Voluntary Motion.

Obscure Ideas.

5* *1

^ Organic Sensibility. 2 *o *o Instincts, or Consensual §

§ '£ w Actions. ».

* § 5 fe

=5
1 ?

W VH

The Organic Life. o *« i Involuntary Motion.

284 THE SCIENCE OF LIFE.

In the general account of the nervous system (Chap.
XV., Sec. i) it was stated that many motions were merely
reflex and involuntary. Many such motions are also
without consciousness. It is probable that a very large
proportion of the movements of the lower animals are
of this character. Other motions depend on organic
contractility responsive to an external stimulus, as when
a piece of muscular fiber contracts on being scratched
with a pin. Ciliary motions, the closure of the leaves of
Venus'-flytrap (Dionaa) on being touched by an insect,
and the movements of the Sensitive plant, may thus be
accounted for. Some motions, as the sleep of plants,
depend on the periodicity of functional activities, and
others, as the bursting of seed-vessels, may be owing to
Endosmose. Mere movement, therefore, is far from in-
dicating consciousness.

" How early does consciousness arise ? If we inter-
pret, as we are constantly doing, the experience of lower
animals by that of higher ones, we should answer, With
the very commencement of animal life. Indeed, noth-
ing but conventional sentiment would prevent our attrib-
uting, under this method, a feeble consciousness to some
plants. If, however, we reason from the character of the
nervous system, which is undoubtedly the sole organ of
consciousness, and from the stages in development at
which a conscious experience can enter as a profitable
factor, we shall be inclined to believe that consciousness
especially characterizes the Vertebrata, and appears first
in the higher Articulata and Mollusca. The phenomena
of consciousness undoubtedly increase greatly in vigor
and in value as we pass up through the Vertebrata, and

THE HUMAN TYPE. 285

this form of activity is, in its governing relations, col-
lected and specialized in the cerebrum." *

Without attempting to dogmatize upon a subject so
imperfectly known, we may suggest that many of the
habits of Ants, Bees, and even of animals of a more prim-
itive type, afford as good evidence of consciousness as
the actions of human creatures themselves.

6. The consciousness of self, or general corporeal sen-
sitiveness, is the earliest sign of individuality, or personal
knowledge. This is previous to the senses, and inde-
pendent of the nervous system. It manifests itself in
animals without nerves, as the Polyps, and seems to be
a necessary attribute of animal life. Yet this most prim-
itive and most clearly innate faculty implies mind, for
by it we know that our body is our body. The corporeal
structure is an object of which the mind takes cogni-
zance. The presence of this sensitivity proves the ex-
istence of something distinct from the body.

7. The consciousness of the physical conditions or
states of the body — as tonicity, languor, hunger, thirst,
warmth, and cold — has been termed common sensation,
or coenasthesis. It is especially conducted, at least in the
higher animals, by the ganglionic or sympathetic sys-
tem of nerves. By means of the connection of this with
the cerebro-spinal system the various affections of the
mind and body mutually act upon each other, rendering
the phenomena quite complex. Certain obscure ideas,
of which one may be said to be half-conscious, and which
taken together make up what we call the disposition or
temper of a man, are the result of organic sensibility act-

* Bascom's " Comparative Psychology."

286 THE SCIENCE OF LIFE.

ing upon the common sensation. What Dr. Carpenter
terms " consensual actions " may also originate here, as
well as from sensation proper. In this term that emi-
nent physiologist includes "all the purely instinctive ac-
tions of the lower animals, which make up, with the u re-
flex," nearly all the animal functions in many tribes, and
which are peculiarly elaborate in their character and
wonderful in their results in Insects. Such automatic
and involuntary actions as vomiting excited by the sight
of a loathsome object, a bad smell, or a disagreeable
taste, or laughter excited by tickling, are also classed
under this term.

8. Sensation, or special sense, is caused by an impres-
sion on certain parts of the nervous system, which are
hence called sensitive. For sensation two things are
necessary: an impressible state of the sensitive organs,
and a perception by the mind.

9. Perception is the evidence we have of external ob-
jects by means of the senses. It is necessary that the
organs and nerves be sound, or false perceptions will re-
sult. Ringing noises in the ears, floating specks before
the eyes, and many spectral illusions, have their origin
in a diseased condition of the organs. Yet that percep-
tion is an attribute of mind is evident from the fact that
attention is required. The senses may be impressed by
their appropriate objects, but without attention they are
not perceived.

10. Memory implies a former conscious experience,
either of a physical or mental kind ; its retention, revival,
and recognition. The laws of memory, as they are called,
or circumstances which excite recollection, have been

THE HUMAN TYPE. 287

enumerated, as resemblance, contiguity, cause, effect,
and contrast.

11. The mind itself may produce in the sphere of
consciousness, ideas, sentiments, emotions, and imagina-
tions. For the manifestation of mental phenomena it is
doubtless important to have continuously healthy nerve-
structure and other bodily organs, since the most ac
complished artisan cannot exhibit his full powers with
imperfect tools and materials ; yet as the injury or de-
struction of the implement is no proof of the annihilation
of the artisan, so the injury or even destruction of the
body may not affect the soul. The mind is popularly
supposed to be dependent on the brain, yet medical
authorities show that every portion of the brain has
been, in one instance or another, destroyed or disorgan-
ized without affecting what are supposed to be the cor-
responding intellectual powers. Abercrombie tells of a
lady in whom one half the brain was disorganized, but
who retained all her faculties to the last, and many such
instances are 'on record. There is no constant relation
between the integrity of mind and body. The mind may
suffer intense agony while the body is in perfect health,
or remain in calm serenity while the body is tortured or
is losing its vital powers.

12. Ideas, in a general sense, refer to any thing present
to the mind as an object of thought, whether present
really or representatively. Some ideas are related to
experience, as the principles of mathematics, notions of
figure, extension, number, time, and space. Others are
independent of sensible representation, as the ideas of
good and evil, just and unjust, true and false.

288 THE SCIENCE OF LIFE.

13. Sentiments refer to feelings of esteem, gratitude,
patriotism, etc., but emotions to mental pleasure or pain.
The emotions are often very complex, and influence
every part of the nature, physical and mental ; as hope,
joy, melancholy, love, and anger.

14. Imagination is a term which represents the power
which the mind has of combining ideas. The images
produced by this faculty are sometimes so vivid as to
affect the organs of sense, and occasion morbid sensual
delusions, as well as to influence the organs of motion,
secretion, etc. No proof could be more positive of the
independent agency of the mind. In its highest degree
imagination leads to creative fancy, or poetic power. In
some of its flights it may encroach upon the prerogative
of conscience, and lead to self-deception unless held in
check by the precepts of Divine revelation.

15. Conscience has been called the moral sense, moral
faculty, moral judgment, and susceptibility of moral
emotions. It may also be termed the inspirational ca-
pacity of the soul. It is that faculty, or combination of
faculties, by means of which we have ideas of right and
wrong respecting actions, and corresponding feelings of
approbation or disapprobation. Faith, in the scriptural
sense of the term, is not belief, but the volitional activity
of the mind in the sphere of the conscience,

16. Judgment is the decision of the mind after com-
parison. It is altogether a mental function. It is an act
of the mind upon and within itself.

17. Volition is the dominion exercised by the mind
over itself, employing or withholding its faculties in any
particular action. It is synonymous with free agency,

THE HUMAN TYPE. 289

and is an essential attribute of spirit, since the very idea
of spirit supposes self-action. Feuchtersleben judiciously
distinguishes between the essential freedom of the spirit
and the freedom of the spirit linked to the body. He
shows that freedom may, first, limit itself, so far as the
spirit makes itself the slave of sin or error; second, it may
be limited by physical laws ; third, it may be limited by
organization. As to the first, the free man is good and
wise ; as to the second, powerful; as to the third, healthy.

1 8. This brief examination of human endowments
shows as great a difference between men and brutes as
exists between animals and vegetables, or between vege-
tables and the mineral world. It is considered by many
that each department of nature becomes higher through
the addition of something which the next below it did
not possess, and as the differences of the animal and
vegetable world form successive additions to a common
original plan or system of organization, we find fore-
shadowings or prophecies of the characteristics of higher
forms. Thus the regularity of the crystal suggests to
the imagination the organization of the plant, and the
motions of plants foreshadow the nervous system. Thus,
too, the higher animals have vague and indistinct analo-
gies of the vast endowments of man.

19. The unity of man was generally conceded by the
early naturalists, but has been largely debated in recent
times. Agassiz himself held to different creations, al-
though believing they were a unit as to intellectual and
moral nature. The discussion continued, until a few
years ago it appeared to be the settled creed of men of

"advanced" views to deny man's unity. Yet one point
25

290 THE SCIENCE OF LIFE.

after another has been changed, until, in the language
of Mr. Tylor,* " it may be asserted that the doctrine of
the unity of mankind now stands on a firmer basis than
in any previous ages."

20. Respecting the antiquity of man upon the earth,
it is very plain that the differences between the Hebrew,
Samaritan, and Greek Pentateuch are such as to forbid
any settlement of the question by a reference to the
Scriptures. Long before the modern discussions on this
subject biblical scholars doubted if it was the design of
the Scriptures to reveal either the antiquity of man or
the age of the earth. Yet the discovery of human re-
mains at Abbeville and other places, the remains of lake-
dwellings in Switzerland, and the shell heaps in Den-
mark, are nowise inconsistent with the view of a
degradation of some races from a more highly civilized
condition. The ruins of ancient nations certainly point
to an early civilization which was remarkable for extent
and splendor. As to the time required for these changes,
Dana, in his " Manual of Geology," says: " The evidence,
as it at present stands, does not necessitate the carrying
of man back in past time, so much as the bringing for-
ward of the extinct animals toward our own time."

21. The numerous varieties of the human species may
be divided into four principal races, which comprise sec-
ondary and mixed races, each including a number of
families and nations: 1st. The White race, also, but er-
roneously, called Caucasian. Its original country, judg-
ing from the comparison of languages and historic testi-
mony, lay between the Mediterranean, the Red Sea, the

*Art., Anthropology, in Encyc. Brit., ninth edition.

THE HUMAN TYPE. 291

Indian Ocean, the steppes of Central Asia, and the Him-
alaya Mountains. From thence it has spread into India,
Arabia, Syria, Asia Minor, and Egypt. 2d. The Red,
inhabiting only America. 3d. The Yellow, which has
existed in China from remote antiquity, and has spread
into all countries inhabited by Mongolians. 4th. The
Black, which belongs to Central and Western Africa,
and is distributed over the tropics from the east coast
to Australia. It is doubtful if either of these races rep-
resents the primitive type of man.

22. We close our brief survey of life with the religious
sentiments of the Psalmist : *• I will praise thee ; for I
am fearfully and wonderfully made: marvelous are thy
works ; and that my soul knoweth right well. My sub-
stance was not hid from thee, when I was made in
secret, and curiously wrought in the lowest parts of the
earth. Thine eyes did see my substance, yet being im-
perfect ; and in thy book all my members were written,
which in continuance were fashioned, when as yet there
was none of them. How precious also are thy thoughts
unto me, O God ! how great is the sum of them ! If I
should count them, they are more in number than the
sand : when I awake, I am still with thee. . . . Search me,
O God, and know my heart ; try me, and know my
thoughts; and see if there be any wicked way in me.
and lead me in the way everlasting."

INDEX.

Acineta, the, what, 16.

Acrogens, families of the, 109.

Actinozoa, the, 171, 177.

Agassiz on evolution, 41.

Agave, or aloe family, the, 129.

Algae, families of the, 91.

Algae, the higher, 99.

Amaryllidaceae, (amaryilis family,)
the, 128.

Amoeboid movement, why so called,
29.

Amphibia, the, 242, 251.

Amphibia, why so called, 250.

Analogous, anatomical import of the
term, 76.

Anatomy, import of the term, 9.

Anaxagoras, teachings of, IT.

Animal kingdom, four primary di-
visions of the, 78.
subdivisions of the, 82.

Animals, souls of, 13.

Arachnoidiscus Ehrenbergii, the, 93.

Arrowroot family, the, 128.

Articulata, the, 213.

Articulates, construction of the, 78.

Arum family, the, 131.

Asteroidea, the, 185.

Atomic theory, the, noticed, 18.

Aves, or birds, 256.

Banana family, the, 127.

Beale, Dr., quotation from on life,

17-

Bichat's definition of life, 12.
Bimana, import of the term, 278.
Biology, import of the term, 9.
teachings of, 10, 25.
confirmatory of dualism, n.
Bioplasm, what, 26, 33.
how nourished, 26.
all animal life originated from,

27.

growth an essential property of,
30.

Birds, families of, 256.
Blood, circulation of the, in verte-
brates, 241.

in amphibia and reptiles, 242.
in birds and mammals, 242.
Botany, definition of the term, 9.
Brachiopod, the, 192, 196.
Bromeliaceae family, (pine apple,)
128.

Carnivora, (beasts of prey,) the, 275.
Carpenter, Dr. W. B., his definition

of life, 12.

Cephalopodae, the, 192, 208.
Characeae, the, 109.
Ccelenteratae, the, 171.
Coleridge, on life, 12.
Comatulidse, the, 185.
Confervas, the, 91.
Coniferous plants, the, 142.
Conjugateae, (stoneworts,) the, 91.
Conscience, 288.
Consciousness, 282.
Construction of mollusks, 78.

of radiates, 78.

of vertebrates, 78.
Crustacea, the, 220.
Cuvier, his divisions of the animal

kingdom, 78.
Cyperaceae, the, 125.

Democritus, teachings of, 10.
Desmidiaceae, family of the, 88.
Diatomaceae, family of the, 92.
Diatoma vulgare, the, 95.
Dipnoi, the, 250.
Dualism, 10, 18, 37.

Echinodermata, (spiny-skinned,) the,

•171, 184.

Edentata, (toothless,) the, 269.
Ehrenberg, Professor, on Vorticella.

14.
Electricity, -powers of, 54.

294

INDEX.

Endogens, (to produce within,) the,

122, 132.

Equistaceae, (horsetails,) the, 113.
Evolution, import of the term, 40.
not a modern science, 41.
Agassiz on, 41.

Exogens, (to .produce outward,) the,
137, 160:

Family, or tribe, a, what, 74.

Ferns, 114.

Fishes, 245.

Functional character of organs, 77.

Fungi, 103, 105, 106.

Gasteropoda, the, 192, 2OI.
Generations, alternation of, 48.

three modes of, 49.
Genus, what, 75.
Ginger family, the, 128.
Graminese, (grass family,) 124.
Grammataphora, the, 95.
Gregarinidse, the, (parasitic plants,)

162.

Growth an essential property of bio-
plasm, 30.

Haeckel, on life, 12.
Heliopelta, (sun-shield,) the, 95.
Hepaticre, (liverworts,) the, 112.
Homologous, import of the term, 76.
Horsetails, the, 109.
Human type, the, 281.
Hydra, why so called, 172.
Hydrozoa, the, 171.

Ideas, relations of, 287.

Imagination, the, faculty of, 288.

Inanimate things incapable of pro-
ducing animate, 19.

Infusoria, the, 14, 16, 23, 24, 164.

Insecta, the, 227.

Invertebrates, nervous system of,
244.

Iridacese, (iris family,) the, 128.

Isthmia nervosa, the, 95.

Judgment, the, faculty of, 288.

Lamellibranchiata, the, 192, 196.
Leucippus, teachings of, 10.
Lichens, the, 101.
Life, various definitions of, 12.
the result of power, 21.

Light, influence and action of, 54.
Lily family, the, 130.
Liverworts, (hepaticee,) the, 109, 112
Long-wings, the, 260.

Man, 281.

antiquity of, 290.

unity of, 289.

varieties of, 290.
Mammalia, the. 267.
Marantaceoe, (arrowroot family,) the,

128.

Marsipobranchs, the, 247.
Marsupiala, (pouch-bearers,) the.

269.

Memory, 286.
Molecular movement, what, 29.

coalescence, what, 56.
Mollusca, the, 192.
Mollusks, construction of the, 78.
Monera, the, 162.
Monism, the theory of, 10, 17.
Morphology, import of term, 9.
Mosses, u 6.

Navicula, the, 96.

Nervous system of vertebrates, 242.

of invertebrates, 244.
Nostocs, what, 91.
Nutrition essential to life, 31.

Orchids, the, 129.
Order, an, what, 74.
Organic nature, unity of, 73.
Oscillatoria, what, 01.
Osmotic action, what, 55.

Palmellacece, family of the, 87.
Palmogloea macrococca, the, 84.
Parentage, sexual and non-sexual,

43-
Park, Mungo, striking experience

of, 120.

Partheno-genesis, what, 49.
Perception, faculty of, 286.
Pharyngobranchs, order of, 247.
Physiology, import of the term, 9.
Pigeon, 263.

Pine-apple family, the, 128.
Plato, teachings of, u.
Polyzoa, (sea-moss,) the, 192.
Primitive forms of life, simple, 27.
Protococcus pluvialis, the, 85.
Protophytes, life-history of the, 84

INDEX.

295

Protoplasm, physical basis of life, 28.
Protozoa, or primitive animals, 161.

Quadrumana, (four-handed,) the, 276.

Radiates, construction of, 78.

ho\v distinguished, 170.
Haveners, the, 265.
Reptiles, the circulation of the blood

in, 245.

Reptilia, the, 252.
Resemblance, parental, 43.
Rhizopoda, what, 162.
Rodentia, (gnawers,) the, 270.
Runners, the, 262.

Science not opposed to revealed

truth, n.

Scratchers, or fowls, the, 262.
Screw-pine family, the, 131.
Scriptures, the, teach dualism, u.
Sedges, the, 125.
Sensation, faculty of, 286.
Sentiments and Emotions, the, 288.
Short-wings, the, 259.
Species, a, what, 75.
Spencer's definition of life, 12.

Sponges, the, 167

Spontaneous motion a necessary ac-
companiment of life, 29.
Swimmers, the, 259.

Teleosls, the, 248.
Thallogens, families of the, 98.
Tissue, what, and how formed,- 52.
Tunicata, the, 192, 195.
Type, a, what, 73, 75-

Urodela, the, 250.

Vegetable Kingdom, divisions of

the, 8 1.
Vertebrates, construction of 78, 239

nervous system of the, 242.
Vertebrates, five classes of, 245.
Volition, what, 288.
Volvocinere, family of the, 87.
Vorticella, the, 14, 16.

Waders, the, 260.
Worms, the, 214.

Zingiberacene, the, 128.
Zoospores, the, 88.

THE END.

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