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THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

POPULAR ILLUSTRATIONS

LOWER FORMS OF LIFE.

"""s

^•~ s

POPULAR ILLUSTRATIONS

LOWER FORMS OF LIFE

I.— THE PKOTOPHYTON.
II.— THE PROTOZOON.
III.— THE CGELENTERATA.

BY

C. R. BREE, H.D., F.L.S., F.Z.S.,

Senior Physician to the Essex and Colchester Hospital,
AUTHOR OF "THE BIRDS OF EUROPE NOT OBSERVED IN THE BRITISH ISLES;" "SPECIES NOT

TRANSMUTABLE, NOR THE RESULT OF SECONDARY CAUSES," &C., &C., &C.

LONDON :
HORACE COX, 346, STRAND, W.C.

1868.

LONDON :
PRINTED BY HORACE COX, STRANP. W.C.

PREFACE.

THE following pages were published in a series of articles in the
Field newspaper, with the object of making the study of Natural
History more intelligible to the general public than a more rigid
adherence to scientific systematic writing would have done. While
endeavouring, however, to popularise the subject, I have taken
especial care not to degrade it by sacrificing truth to what may be
called sensational science. My object has been rather to prepare the
mind for deeper delving in the rich mines than to make it content
with any glittering specimen it may meet with on the surface. The
subject is therefore necessarily incomplete, even as to a thorough
examination of the three great divisions of Nature with which I have
dealt. But I have endeavoured to bring out all their salient points,
and have, I trust, succeeded in making them clear and intelligible.
While expressing my opinion with perfect freedom and independence,
I have avoided controversy as much as possible. There are many
means open to the student in which he may study with advantage
the two great lines of thought by which the primary or secondary
character of species are advocated.

The great book of Nature will always be interpreted differently so
long as the human mind differs in its powers of thought and
reflection.

But the student will best prepare himself to decide rightly on
this subject by a careful study of facts. I believe this will lead

VI PEEFACE.

him to a belief in the adaptation of every part of organised
structure to its special use by the preconceived design of a Divine
Architect, rather than to that cold and unimaginative doctrine
which views all nature as the result of secondary laws which
subserve to " arrested development," " natural selection," or the
" struggle for existence." I do not say this in any spirit of detrac-
tion ; for I know that some of our ablest and most zealous workers
hold views to which the last remark will apply. But there is plenty
of room in the field of scientific research for the greatest diversity
of opinion. The problem of the " origin of species " will, in all
probability, never be unfolded to the human intellect; for, carry
back the imagination from the highest to the humblest organic
form, still the " incoming " of the latter is as great a mystery as
ever. The FINITE cannot comprehend the INFINITE mind.

Should this volume be received favourably, I shall be encouraged
to go "onward" in the scale, and finish in another (the-In vertebrate)
class of animal life.

COLCHESTER, April 20, 1868.

CONTENTS.

PART I.— THE PROTOPHYTON.

CHAPTER I.

The Natural History of a Grain of Wheat ... page 1 — 7

CHAPTER II.

The Natural History of a Grain of Wheat (continued} 7 — 12

CHAPTER III.

The Natural History of a Grain of Wheat (concluded} 12—18

PAET II.— THE PROTOZOON.

CHAPTER I.
The Protozoa : The Gregarina and Infusoria 19—25

CHAPTER II.
The Infusoria (continued} 26—33

CHAPTER III.
The Rhizopoda 33—40

CHAPTER IV.

The Rhizopoda (continued}— The Foraminif era 40—48

CHAPTER V.
The Foraminifera in Time 48—58

CHAPTER VI.

The Radiolaria— The Sponges , 58—68

CONTENTS.

PART III.— THE CCELENTERATA.

CHAPTER I.
The Hydrozoa page 69 — 78

CHAPTER II.

The Hydrozoa (continued} — The Calycophoridse ... 78 — 86

CHAPTER III.

The Hydrozoa (continued ) —The Physophoridae 8 6 — 92

CHAPTER IV.
TheMedusidae 92—99

CHAPTER V.
•Phosphorescence of the Sea — Reproduction of the Hydrozoa ... 99 — 105

CHAPTER VI.
TheActinozoa 105—110

CHAPTER VII.
Coral ... „.. 111—117

CHAPTER VIII.
Coral (continued} 117 — 122

CHAPTER IX.
Coral Islands 122—129

POPULAR ILLUSTRATIONS

LOWER FORMS OF LIFE.

PART I.
THE PROTOPHYTON.

CHAPTEE I.

I PEOPOSE to offer a series of chapters on the various phases of
organic life, commencing with the lowest form of vegetable
structure, and ascending in the scale upwards.

I hope to make these illustrations both interesting and instructive.
I shall endeavour to present the inner pages of the great book of
nature in a form which will be readily understood by all classes of
readers.

Thus, while they may enjoy that true delight by means of their
senses, which is afforded by looking at beautiful scenery, or watch-
ing the habits of the creatures by which it is peopled, I shall not, I
think, be asking too much in calling upon them to go a step further,
and to follow me in the intellectual investigation of organic structure,
its uses, and its adaptations to the purposes for which living things
were created.

With these remarks, I proceed to ask — What is the Protophyton ?

It is the type of the ultimate structure of plants, and before we
study the animal organisation it is necessary to have a just concep-
tion of that of the vegetable. The protophyton is a simple cell,
only seen through the microscope, containing a fluid and having a
nucleus, and what are called cell-walls.

In its simplest form, as seen in the fungus which appears in vast
districts on the surface of snow, and known as red snow, this cell
constitutes the entire plant. The protophyton is distinguished from
the protozoon, which is the type of animal structure, in the im-
portant fact that it absorbs carbonic acid gas from the atmosphere,

B

POPULAR ILLUSTRATIONS OF

and emits oxygen ; while the latter emits carbonic acid and absorbs
oxygen. They may be diagrammatically represented in the follow-
ing figures :

Proto-phyton (from llgurog, Proto-zoon (from

first, and 3>urov, a plant). first, and Zuov, an animal).

These cells are of all shapes, seldom so round as represented in
the diagram. They essentially consist of what are termed cell-walls,
having one or two layers (a), and of cell contents, which are a fluid
represented by the cross-lines ; small particles of matter termed
molecules or granules, held in solution by the fluid ; and a nucleus (6),
which often contains a still smaller body, termed the nucleolus. Now,
these cells exist as separate and distinct beings — living, reproducing,
and occupying very important positions in the economy of nature.
From these cells all living structures, vegetable or animal, are
built up.

It is the Protophyton which will for the present engage our
attention ; and I propose to illustrate its development in the vege-
table world by describing

THE NATURAL HISTORY OF A GRAIN OF WHEAT.

I will commence my history with the grain as it is stored up in
the barn of the farmer, or rather just as he is going to plant it in
the autumn. If the seed is examined, a small whitish spot will be
noticed on the lower part of the back. This is the germ of the
future plant, which if placed under certain circumstances will have
its dormant life called into action, and will begin to grow.

Now in the very threshold of our inquiry we see a most beautiful
provision, and are met with a very perplexing question — What is
life ? This question has puzzled wiser heads than my own. It
cannot, in fact, be answered. And why ? Simply because the mind
of man is finite, and life is one of the attributes of Infinity. We
have nothing with which we can compare it, and therefore as man's
reason essentially depends upon the power of comparison, we cannot
nor ever will solve the difficulty.

There has been a tendency in the discussions of recent days to
identify the vital with the physical forces of attraction, as evinced in

THE LOWER FOEMS OF LIFE.

chemical combinations, or electricity, or heat ; but such reasoners
make no real progress in the inquiry. Life is the great antagonistic
principle to chemical forces, and hence arises an insurmountable
difficulty in proving that one is a correlation of the other. Elec-
tricity may be a correlation of heat, because they can, it is said, be
converted into each other. Neither of them, however, will give life
to an inanimate or unorganised body.

And so it arises that there is great beauty in the provision which
is fore-ordained that the life of the organised grain of wheat should
remain dormant until the circumstances necessary for its existence
as a living thing are presented to it. These circumstances are the
united presence of heat, moisture, and atmospheric air. This
dormant condition of the seed is therefore one of the attributes of
life. That the life, though dormant, is really a powerful force is
proved by the fact that it prevents the constituents of the seed from
being subject to the chemical forces which decompose and re-arrange
the elements of dead matter. So long as the above conditions —
heat, moisture, air — are kept away from the seed, its vitality will
lie dormant, and its physical condition remain unaltered for any length
of time that the imagination can depict.

But the wheat-seed has a great and
important office to fulfil in the world.
Its destiny is more or less connected
with that of the whole human race. It
is the means by which that daily prayer,
" Give us this day our daily bread," is
answered, and due provision made that
it should perform the duties for which
it was created, Brought under the
united influence of heat, moisture, and
atmospheric air, all of which it meets
with in the soil, we see a very beautiful
process — the seed germinates.

Now let us for a moment examine
Fig. 2, which represents a longitudinal
section of a grain of wheat, with the
parts of the germ or embryo enlarged
(after Henslow).

First observe the two skins or cover-
ings, one (a) is called in botanical

language the "pericarp" or outer skin, and (b) the "endocarp"
or integument or inner skin. These skins are well known to
millers, for the thinner they are the more flour and less bran is
yielded to the grindstones. At the top of the section (c) is the

4 POPULAR ILLUSTRATIONS OF

beard, and at the bottom (e) is the embryo or germ, while (/)
represents the flour of the grain, or, as it is called botanically, the
albumen of the seed.

Let us examine the embryo more particularly. As it lies in the
seed it can readily be divided into four portions. An upper portion
(d), which is the young seed leaf or cotyledon, is single, and there-
fore the class of plants to which the wheat belongs is called " mono-
cotyledonous." The second portion of the embryo (g) represents
the plumule or bud of the plant, while that part marked (i) repre-
sents the root or radicle, and the portion between the radicle and
plumule marked (K) represents the stem. The embryo is, in fact, to
all intents and purposes a young plant, which, like young people,
requires a start in life. And this start is given to it by a con-
junction of the "circumstances necessary for its existence," which,
as before stated, are heat, moisture, and air.

All the summer the soils of our fields are absorbing heat directly
from the sun and stars. Heat is a force and principle in nature
which has many most interesting properties, for a description of
which I must refer to works on natural philosophy. Water is
formed by the chemical union of two gases (hydrogen and oxygen),
which are elementary principles in nature, and, like all other
chemical compounds, they unite to form water in fixed and definite
proportions. By volume this union is as 2 of hydrogen to I of
oxygen, the size of an atom of hydrogen being double that of
oxygen. By weight the proportions are, hydrogen 1, and oxygen 8
— the latter atom being eight times heavier than that of the
former ; and the combining proportion of water when it unites
chemically with other bodies, as it does with sulphuric acid, is 9.
Atmospheric air is a mechanical mixture of two gases and a solid
body — three elementary principles of nature. These are — nitrogen
(an element which enters largely into the composition of animal
structures), oxygen, and carbon. The first two are in the proportion
of nitrogen 79 and oxygen 21 parts, less the 1000th part, which is
occupied by a union of carbon and oxygen forming carbonic acid — a
most important part, as we shall see, of the food of plants.

Let us now proceed to notice what takes place when the seed is
brought into contact with heat, moisture, and atmospheric air.
First, the embryo plant begins to grow ; the dormant life springs
into action ; the bud, enveloped or surrounded by its cotyledon or
seed leaf, appears above the ground, while the radicle or root makes
a similar movement into the ground below.

Let us linger a moment and inquire what is meant by " growth."

The embryo is originally a cell, known as pollen grain, containing
molecular matter, that is, matter having the greatest amount of

THE LOWER FORMS OF LIFE.

division known to the highest power of our microscopes. How this
pollen grain gets into the seed I will show by and by. But the
embryo now must be considered as an aggregate of four protophytic
cells, containing an albuminous or nitrogenous fluid (similar some-
what in its properties to white of egg), molecular matter, and a
nucleus. Now, each of the four cells, the embryo cotyledon,
plumule, caulicle, and radicle (Fig. 2, p. 3), multiply, and so each
organ grows. But this growth requires new matter to be supplied,
so that the vital powers of the cell can then form new material. In
other words, the young cells require feeding. Helpless as a new-
born babe without a mother would be that young embyro plant
unless wise forethought had made provision to meet its necessities.
As yet, the young plant cannot help itself. Its roots and leaves are
unformed. Just, however, as milk is provided for a helpless babe,
so is food provided for the helpless plant. That food is the flour
which, when the seed is ground, makes our bread. It is the
albumen of the seed (/, Fig. 2, p. 3). But the plant, whether in its
embryonic or matured condition, can only take in food in a fluid
or aerial condition. Now, the flour of the wheat-seed is not easily
soluble, at least, not so as to be taken up by a tender organism like
our wheat-plant. How is this difficulty overcome ?

Nothing in nature is more striking and beautiful than the answer
to this question. If the flour of the wheat-seed were more soluble
it would be spoiled when subjected to wet ; it would not keep in our
granaries, and its use as human food would be lost to mankind.
When subjected, however, to moisture, heat, and atmospheric air,
the flour is chemically decomposed, and the starch which it contains
is converted into sugar, which is soluble, and in that condition can
be taken up as food by the embryonic plant. To understand this
clearly, a word or two must be said about the chemical constitution
of a grain of wheat.

It consists of organic or vegetable, and inorganic or mineral sub-
stances. The vegetable are starch and gluten ; the mineral, phos-
phorus, lime, iron, magnesium, sodium, potassium, silica, and
sulphur. There are also certain gases — chlorine, oxygen, carbon,
hydrogen, and nitrogen.

To avoid confusing the non-chemical reader, I will confine myself
for the present to the chemistry of the change which is undergone
by the flour of the grain during germination.

Starch, of which the best wheat-flour contains from 60 to 66 per
cent., is thus composed — in atoms :

Carbon. Hydrogen. Oxygen.

Starch 12 10 10

Grape sugar is composed of 12 14 14

6 POPULAR ILLUSTRATIONS OF

It will be seen that to convert starch into sugar, it is only
necessary to add four atoms of hydrogen and four of oxygen. How
is this obtained ? Why, as I have before remarked, one of the
conditions of germination is the presence of moisture or water,
which is composed of hydrogen and oxygen. Under the influence,
then, of this vital force — of that mysterious power we term " life "
— this wonderful change is effected which enables the young plant
to feed.

But what becomes of the gluten of the flour ? It is contained
therein in the variable proportions of 12 to 20 per cent., and may
easily be separated from the starch by making a portion of flour
into paste with pure water, and then carefully washing it out on a
fine cloth. The starch, as a milky solution, will pass through the
cloth, leaving a greyish, elastic, insoluble substance behind, called
gluten. Now, this "gluten" of wheat-flour is composed of a small
proportion of a peculiar matter, to which its sticky or adhesive
properties are due, called "gliadine," and a large proportion of a
substance called " vegetable fibrine," which is identical, in chemical
composition, with white of egg or " albumen," with the chief con-
stituent of flesh or " animal fibrine," and with the chief constituent
of milk or "caseine," all of which are essentially parts of animal
bodies. The great difference between gluten and starch is owing to
the presence in the former of rather more than one-sixth of its entire
bulk of nitrogen, or as it is sometimes called " azote." • If we wish to
produce fermentation in the sweet, sugary wort of beer, we intro-
duce what is called a ferment — viz., yeast. If we wish to convert
our milk into cheese, we do so by introducing into it a piece of
rennet, by which decomposition is effected. So, nature in the
germination of the seed produces a ferment, through whose agency
the starch is converted into sugar, and it is done in this wise.
The gluten is decomposed, and is converted into what is called
diastase, which acts in decomposing the starch just as the yeast does
the sweet wort, or rennet with the milk. Gluten deprived of its
gliadine is constituted in a hundred parts, as follows :

Carbon. Hydrogen. Nitrogen. Oxygen.

54-60 7-30 15-81 22-29

And by an interchange of these elements diastase is formed. This
diastase alters the molecular arrangement of the starch, and changes
it first into gum or dextrine, and then into grape sugar ; during
which process there is an evolution of carbonic acid from the excess
of carbon and oxygen.

Such is the process by which the embryonic plant is provided in
infancy with the means of subsistence.

THE LOWER FORMS OF LIFE. 7

Now what does this process involve : — (1) The presence of the
flour of the seed ; (2) that this flour should be of such a constitution
and consistency as to be able to resist the decomposing agencies
around it, until it is called into use by the vital energies of the
embryonic wheat-plant ; and (3) that it should be so constituted
chemically as to be easily converted into the soluble food requisite
for the young plant.

But the plant though a living, is an unconscious being. Though
it performs, it can have no share in the prospective issue involved in
these processes. As reasoning creatures, we should do very much the
same if we had the future of the wheat-plant to provide for. We
could, however, only do this by the faculties which constitute
our reason, that is, by comparing the experience of the past with the
necessities of the future ; but in this process of germination all is
done without knowledge, feeling, sense, or reason, and we therefore,
and of a necessity from which there is no escape, come to the con-
viction of the operation of a Great First Cause.

OHAPTEE II.
THE NATURAL HISTORY OF A GRAIN OF WHEAT

, (continued*).

HAVING started our young plant in life it makes good use of its
time, feeds upon the sugary food provided for it, and in due season
the wheat-plant produces roots.

Every one knows what the root of a plant is, as it appears to the
eye. Comparatively speaking, few people know it as an organised
structure.

The cell which forms the embryonic radicle (Fig. 2, p. 3) multi-
plies, and the root grows in the form of a minute filament or thread-
like organ, which strikes down into the earth. This filament in the
wheat-plant is repeated many times, each filament rising from what
is called the axis (Fig. 3, p. 8). Now these cells multiply in at least
three different ways.

First : They divide into two or more portions — each portion
becoming a perfect cell, or one cell buds out, as it were, from another,
and this mode of cell growth is called exogenous, because the change
occurs outwardly.

Secondly : Cells form within cells, and, the containing cell
bursting, its numerous contents each assume the functions — as they
possess the structure — of perfect cells. This is called the endo-
genous formation of cells, the change taking place from within.

8

POPULAR ILLUSTRATIONS OF

Thirdly : The most important mode of cell-formation carries us a
step beyond the cell. The ultimate form of matter, as shown by
the highest power of the microscope, exists in atoms called molecules.
Under favourable circumstances a group of these molecules form for
themselves a covering, or cell-wall. This is called the molecular
formation of cells.

Cells also unite together to form larger cells, and this has been
designated the congregation method of increase, and is well exempli-
fied in the growth of the lower forms of vegetable life.

Now cells increasing in one or other of these methods, and
becoming united to each other, some of them forming elongated
tubes, or, as they are called, vascular organs, and the whole sur-
rounded by a delicate membrane or skin, also formed of cells, some-
times called " epiblema," constitute and form the roots of plants.
The main root of most plants striking from above downwards, gives

Fig. 4.

Fig. 3.— Grain of wheat germinating— a, central root of axis— a/, other rootlets covered with
hairs— 6, plumule -c, cellular sheath or " coleorhiza " covering the axis or base of rootlets
— d, the seed (after Balfour).

Fig. 4.— Microscopic view of cast of silica in wheat-stem after boiling in nitric acid (after
Goadby) — a, siliceous plate with serrated edges, which fit in accurately to other plates —
— &, cast of stomata, or breathing-mouth of stem, in flint.

off numerous branches, the ends of which are formed of cells loosely
put together, and thus, having a spongy texture, are called
" spongioles," which are, however, covered like the rest of the root
or rootlets, with the fine delicate membrane above mentioned.

It is through this membrane and the spongy texture of the
spongioles that all the food of the plant obtained from the soil must
pass. It is evident, therefore, that the food must be in a state of
solution.

In the wheat-plant there is no central root. All the rootlets or

THE LOWER FORMS OF LIFE. 9

fibrils spring from the axis, where they are .covered with a cellular
sheath. The centre fibril (a, Fig. 3) being generally considered as
replacing the principal root, it only remains to add that the root or
rootlets is lengthened or extended laterally by cellular additions to
its extremity. In plants whose branches spread, the roots are wisely
ordained to spread also, and thus retain a powerful attachment in
the soil. In the wheat-plant the roots do not extend or branch out
far laterally, because the stem, being branchless, does not require
such a provision.

Having thus formed a clear idea of a root — its branches, cover-
ings, cellular texture, and sponge-like extremities, let us now notice
how it performs its functions. In other words, how does the wheat-
plant feed1?

It is, of course, obvious that the feeding of plants, whether by
their roots, or other means to be treated of hereafter, must have
reference to their growth and perfection, and it is with this connec-
tion in view that I shall treat the subject here. Let us at present
observe the functions of the root. They are connected with one of
the most interesting of natural laws.

If a glass cylinder be filled with a solution of sugar or chemical
salts, and the end covered over with a piece of bladder, and if this
cylinder be then inverted and placed in a jar of pure water, the
following change will take place : two currents will be established
through the bladder, one conveying a part of the solution of sugar
out of the cylinder, the other a part of the water out of the jar into
the cylinder, and these currents are termed in reference to their
directions in or out, "endosmosis" and "exosmosis." Now the root
of the plant is a cylinder, containing in its vascular vessels a fluid
having a density different from the water containing the plant's food
in the soil. The vascular vessels, in fact, contain the excretions of
the plant in solution — and thus a beautiful interchange of that
which is useless with that which is all important as food, is set
up. The excretions pass out by exosmosis through the membrane
covering the spongioles, while the food passes in through the same
membrane by endosmosis. It is impossible to conceive anything
more interesting or suggestive than the application of this well-
known physical law to the means by which plants feed.

We shall see, by and by, as we proceed upwards in the scale of
nature, that all the great physical laws known to man and applied
by him in works of art, have been anticipated in the organisation of
living things.

It is thus, then, that the roots convey the alimentary matter
found in the soil into the plant.

Let us now examine how the stem grows.

10 POPULAR ILLUSTRATIONS OF

If we refer back to Fig. 2 (p. 3), we shall observe the plumule is
marked out in the embryo plant at g.

As the root grows by the multiplication of cells, so does the stem
increase and rise up above the surface of the soil. As the root
derived its primitive nutriment from the sugar of the seed, so does
the stem. The stem is destined, however, for different purposes. It
has to bear the leaves and branches and fruit of the plant. There-
fore, it has to be fashioned with distinct, direct, and unmistakable
reference to these objects. The first leaf of the wheat-plant is the
cotyledon (d, Fig. 2, p. 3). So soon as the stem appears above
the ground, and forms its first true leaf, the use of the cotyledon is
finished, and it dies. Every now and then, however, as the wheat-
plant rises up above the ground, there is formed a kind of platform
from which springs a leaf. This is called a " node," and the spaces
between each node are called "internodes."

What are the exigencies of the wheat-plant ? It has to carry a
heavy ear containing the grain, and provision must be made so that
it shall bear this weight, and bend with it before the stormy wind
without breaking. If the stem were solid it is obvious that it would
snap across and break, and the grain would be lost. Therefore we
find the form of cylinder is adopted, and the geometrical scholar
knows full well that this is the form which a given weight of
material will work up into the strongest support. But annual plants
have, more or less, succulent, soft stems, and unless that of the
wheat-plant were strengthened in a peculiar manner, the stem
would not bear its weight. This is done in two ways ; first, by the
interposition of the nodes ; and, secondly, by incasing the stem
with a coat of flint. I need say nothing about the obvious mode in
which the nodes strengthen the stem. The flinty coat requires a
word or two of notice. If a piece of wheat-straw be boiled in nitric
acid the vegetable matter will be dissolved, and a perfect cast of the
straw in pure transparent flint may be obtained, as shown in Fig. 4,
page 8.

But how is this ? Have I not, in describing the roots, shown that
all matters taken up by them must be in solution, and yet I now
say that the straw contains a cast of flint, which is insoluble in that
which will dissolve almost everything — nitric acid ? How is this to
be explained ? Just in this wise. The soil contains flint in a state
of minute subdivision, but still insoluble. When the elementary
principle, silicon, is acted upon by the oxygen of the atmospheric
air, which is allowed by our system of cultivation to get into the
soil, it becomes oxidised, and "silica," or "silicic acid" the terms
being synonymous, is formed. The silica exists nearly in a state of
purity in rock crystal, common quartz, flint, chalcedony, &c., and

THE LOWER FOEMS OF LIFE. 11

in any form is very insoluble in water or acids, but is readily soluble
in strong alkaline solutions. When, therefore, the powdered quartz
or flint comes into contact with the alkali potash, or soda in the
soil, it produces a soluble chemical compound known as the silicate
of potash or soda, and in this form it is taken up by the roots of
the wheat-plant, and carried through the vascular vessels to the cells
of the stem, where it is deposited as seen in the figure round the
straw, not as the soluble "silicate," but as the insoluble "silica,"
or flint.

And here we have a fine illustration of the operation of vital
force. The cell, by the multiplication of which, as we have seen,
the wheat-stem is built up, I described as the individual proto-
phyton, having the powers of a distinct being ; we find it here acting
as a conscious being would do, for it actually selects the silicate
from the other minerals in the juices of the plant, and then, by
decomposing it, renders it insoluble, and further so disposing it
round the stem of the plant as to protect it against the dangers
with which its future is threatened.

Let us put this illustration of vital force in another and still more
forcible light.

Place a rhododendron, a sunflower, and a wheat-plant in the same
flower-pot filled with soil. The soluble matters in that soil will
pass by endosmosis through the membrane covering the spongioles
of the root into the cellular tissues of the plant. The cell of the
wheat-plant will select the silicate of potash, because a flinty coat
is required for its stem. The cell of the rhododendron will select
the lime and reject the silicate, because its stem is woody and solid,
and does not require flint to strengthen it, while carbonate of lime-
is an essential part of its texture, its branches being designed
merely to carry leaves, flowers, and light seed. In the third place,
the sunflower will reject the silica, and take up the potash and lime.

There are men in the present day who attempt to deny the
existence of a vital as distinct from a physical force. The same class
of men will argue that blind instinct is only a modification of reason.

As I shall hereafter have opportunities of discussing the great
subjects of instinct and reason, I shall content myself here by
noting that they are clearly distinct from each other. The mason
wasp provides food for young that it never sees. There is here no
comparison from experience, and therefore the insect does not act
from reason of its own. The act of the insect is instinctive, but the
power which instituted the great law involved in this act must have
had reason and forethought, or the power of seeing into futurity.
The beaver builds his hut in the same manner as the first beaver
did. It does not improve, therefore it acts from instinct, which is

12 POPULAR ILLUSTRATIONS OF

unchangeable. But man builds a very different house when civilised
to that which he raises in his primeval forest.

Now just as instinct differs from reason, so does physical differ
from vital force. The crystal attracts its elements from their
solution in water, and takes upon itself its destined form now as it
ever did in obedience to natural law, which is purely physical. But
the cell of the wheat-plant selects the flint to strengthen the sides
of the hollow cylinder of straw with reference to the existence of a
world. If that power of selection did not exist in the cells of the
wheat-plant and other grasses, all our cattle, and every human
being on the face of the earth, would perish. The law of attraction
fails to explain the act upon which such a vast issue depends. The
unconscious plant-cell must be a passive agent. It yet performs an
act far higher than anything human reason can effect.

Again, how irresistibly, and yet how unconsciously, are we led
step by step from the physical to the vital — from instinct to reason,
and from reason to the Infinite !

CHAPTER IH.
THE NATURAL HISTORY OF A GRAIN OF WHEAT

(continued}.

THE next stage we note in the history of our young plant is, that
the stem forms leaves. Bearing in mind the modes in which cells
multiply so as to constitute growth, we can understand how the leaf
buds out of the node, and gradually grows to the length and shape
so well known in the wheat-plant.

This leaf is oblong and lancet-shaped. It is covered at its basal
attachment to the stem by a split sheath, and, if minutely examined,
will be found to possess a short stalk or petiole ; and at the
point of junction of the petiole and blade, there is a membranous
expansion, called a ligule. I need not illustrate all this, as plants
for examination are always accessible even in winter.

Then, observe the leaf has two surfaces of different colours, one
looking upwards, of a dark green, owing to the presence in its
surface cells of an excess of a fluid containing a pigment known as
"chlorophylle," which is the universal cause of the green colour of
vegetable life. The other surface, looking downwards, is of a paler
colour, owing to the fact that many of the cells contain air instead of
" chlorophylle."

Now these air chambers have a certain analogy to the air cells of
our own lung, for with the openings by which they communicate

THE LOWER FORMS OF LIFE.

13

with the interior of the leaf, they constitute the breathing apparatus
of plants. These openings or mouths are termed " stomata," and it
is through their media that some of the most important operations
in the economy of the plant are performed. These stomata are very
numerous in the leaves of some plants, such as the lilac, in which
160,000 to the square inch have been calculated under microscopic
examination. And it may be noted here that in water plants, the
leaves of which swim on the water, as the lily, these stomata are in
the upper part of the leaf. (See Fig. 6.)

Now let us go to our friend, Mr. Goadby, and ask him to illustrate
for us the structure of a leaf as seen through the microscope. He
readily furnishes us with the following microscopic view of a trans-
verse slice cut very thin from the leaf of the common garden balsam.

I have selected the balsam to illustrate the structure of leaves,
because it is thick and shows the parts clearly ; but all leaves are

Fig. 6.

a> cellg of the upper cuticle or skin_
6, cells containing chlorophylle — c c, diges-
tive or nutritive cells in central and under
part of leaf d, cells of the lower cuticle
or skin, containing the stomata, or air
openings— e, two spiral vessels.
Fig. 5.

Fig. 5 (altered from Goadby). — Vertical section of leaf of the common garden balsam (highly

magnified).
Fig. 6 (after Balf our) .—Stomata as seen on the upper surface of water plant (Ranunculus

aquaticus, highly magnified).

constructed more or less on the same model. They are, in fact,
formed of a vast number of photophyta, divided into sets, each set
performing a distinct and separate function. Thus we have the top
layer, forming the epidermis or skin ; just below the pigment cells ;
then the digestive or nutritive cells ; and, lastly, the lower skin and
the mouths of the stomata. There are also a series of vessels which
are made up of cells and formed into tubes. These tubes are com-
monly known as veins, and are well seen in the skeleton leaves we
pick up in our garden in winter. In the wheat and allied plants
they run parallel to each other. They are called " vascular vessels,"

14 POPTOAR ILLUSTRATIONS OF

and their use, like our own blood vessels, is to convey the fluids
taken up by the roots to all parts of the leaf where important
changes are effected, and to return it so altered as to subserve the
purpose of nutrition to the plant. These vessels have all more or
less a spiral character, like those shown in Fig. 5, e, p. 13. Some of
them carry air, others fluid. In our wheat-plant these vascular vessels
stop short in their development at a certain stage. In other plants,
as most of our trees, new matter is continually being added to them
externally, so that they ultimately form hard tissue, known as wood.
There is also another system of vessels in leaves called "laticiferous,"
which, in fact, constituted the "proper vessels" of old writers.
They are principally connected with the bark of trees. They convey
a fluid called "latex," red, white, yellow, or colourless. They
divide into very minute branches, only discovered by the highest
power of the microscope. It is from these vessels that the milky
latex exudes when we tear across the leaf of a lettuce. Leaves of
course present an infinite variety, and their study is one of absorbing
interest to the botanist.

I have said enough, however, to give a general view of the
subject, and to allow us to take an intelligible glance at the
functions of leaves.

We have seen that the roots, by means of their spongioles, take
up fluid from the soil containing certain mineral matters in solution.
This fluid is chemically altered, and has added to it organic matter
taken in by the leaf from the atmosphere, and it then becomes the
fluid known as sap. In other words, it is the nutritious fluid of the
plant, bearing to it the same relation as our own blood does to our
bodies.

I have shown also that the protophyton absorbs carbonic acid
from the atmosphere, and it is by this means that the great amount
of charcoal contained in the vegetable growth of the earth is pro-
duced. It is altogether a mistake, therefore, to assume that plants
are injurious to health if grown in our living apartments. Carbonic
acid in excess in our atmosphere is injurious to animal life. Plants
remove it. It is to this power of absorbing and appropriating to its
use the carbon of the atmosphere that we are indebted for our
coal, gas, and fire. It is this which gives the essential element to
the meat produced by our flocks of oxen and sheep. It is, in fact,
a source of infinite blessing and comfort and happiness to the whole
human race. Leaves are the great manufacturers of food in every
part of the world. If we search the highest mountain, penetrate
into primeval forests, or go down into the depths of the sea, we
shall find leaves, or modifications of leaves, ever at work night and
day in preparing the means by which animal life is supported. The

THE LOWER FORMS OF LIFE. 15

herbivorous animal takes the food thus manufactured, and then
others higher in the scale kill and feed upon the meat which it pro-
duces, and thus the great chain of animal existence is preserved.

It would be an insult to the imagination and intellect of my readers
were I to dwell upon the beautiful and sublime thoughts which the
mere mention of this great chain of facts must create in their minds.
But in these pages I do not intend to get too much into what Mr.
Newman happily calls " the groove." I wish rather to read with
them the book of nature as seen in its inner aspect, and to create, if
I can, that real love of the grand facts it presents to us which is felt
by all who prefer indulgence in the pleasures of intellect to those of
sense.

The first great function performed by leaves is to get rid of the
excess of water drawn in by the roots. This is done by exhalation
through the stomata, under the influence of light and warmth.
This exhalation is much larger than ordinary observers have any
idea of. A cabbage, for instance, is known in a warm day to exhale
as much fluid as its own weight. Some idea may be formed of the
quantity of fluid given off by the grass on a common lawn by
placing an inverted tumbler upon it in sunshine, and observing the
rapidity with which drops of water form on the glass inside. This
experiment is best performed, as it was done by Bishop Watson, after
several weeks ' dry weather. He calculated that a meadow, so cir-
cumstanced and cut, during hot sunshine exhaled 6400 quarts of
water in twenty four-hours. Dr. Carpenter has, however, noticed
that the bishop did not allow for the fact that all exhalation is
stopped during the night. But if we divide this by two, still 3200
quarts per acre during twelve hours is an enormous quantity, and
will give us some idea of the rapidity and importance of this
function of leaves.

The excess of fluid being thus removed by exhalation, the in-
organic or mineral matters brought into the leaf by the roots are in
a fit condition to unite chemically with the organic matter taken in
by the stomata from the atmosphere. This function is termed, as in
our bodies, that of respiration, and just as our blood by breathing is
converted from venous into arterial, so is the crude sap changed by
the breathing of the plant into the nutritious fluid known as true
sap. During the process of human respiration, oxygen gas is appro-
priated and carbonic acid is given off ; during that of the plant, the
opposite, as we have seen before, is the case — carbonic acid is taken
in and oxygen given off ; and thus it is that plants purify our
atmosphere.

In addition to the respiratory functions, there is another going on
in leaves which has some analogy to that of our digestion. All the

16

POPULAR ILLUSTRATIONS OF

green parts of a plant contain a pigment called chlorophylle ; this
pigment especially attracts carbonic acid from the air during light
—decomposes it, stores up the carbon, and allows the oxygen to go
free. This process is termed the "fixation of carbon/' and is per-
formed by the green parts of the plant alone.

We are now prepared to go on in our history and to study the
next and final stage : The plant flowers and forms seed.

There is nothing in the wide and glorious field of nature more
beautiful than the details to which I now draw your attention.

The process of flowering and forming seeds is essentially the same
in all flowering plants, although the details vary considerably. I
have said that a leaf is a lateral extension of the stem — so a flower
is merely a modification of leaves without the power of extending
its central portion or axis. When a leaf bud opens, it grows by

Fig. 7. Fig. 8.

Figs. 7 and 8.— Wheat-plant flowering (after Henslow).

extending itself along a real or imaginary line termed its axis. A
flower bud, on the contrary, consists of certain organs growing and
increasing round a central fixed point or axis — and if it varies from
this rule the flower is monstrous.

Everybody knows that an ear of wheat consists of a spikelet con-
taining many separate flowers, each of which leaves behind it a
grain of wheat. Viewed singly these flowers are well represented in
Fig. 7. Those parts of the flower which are usually coloured are in
the wheat-plant green. They are two, and are known in the ripe corn
as the chaff. Botanically they are called " palea" — one inner (a) and
one outer (b). If we tear these palese away we shall expose the
other parts of the flower, as shown in Fig. 8 ; a b constitutes what
is termed the pistil, and is formed of (a) the ovary and (s s) the two
styles, which at the end have a surface which secretes a sticky fluid,
and is termed the stigma (b b). It will be observed that the styles

THE LOWER FORMS OF LIFE.

17

are in our plant feathered. These constitute the female parts of the
flower. The male portion, as it is termed, consists of the three
stamens (c d). The filament (c) is terminated by an oblong bifid-
looking organ (d) ; this is the anther, in which the pollen grains (e)
are formed.

Now the problem to be effected, in order that the grain of wheat
should be formed and the race perpetuated, is that the pollen grain
(e) should find its way into the ovary (a). The
anther (d) opens and casts its pollen upon the
stigma (b), which holds it fast there. Observe
here that, although the ovary only produces one
germ, there are two styles, which is an impor-
tant provision to secure the certainty of the
production of seed. Well, the pollen grain
being caught by the stigma, can get no further,
for, though loose in texture, the style is imper-
vious. How, then, does the pollen grain get
down to the ovary ? Just in this way. The
pollen grain, when sticking to the stigma of
the style, splits its outer coat (for it is a proto-
phytic cell, containing granules, and having
two coats). The inner coat then becomes pro-
longed in the form of a tube, which pierces
the loose cellular texture of the style (Fig. 9),
and makes its way down until it reaches the
ovary, where it finds a door, termed a micro-
pyle, ready open to receive it. In the mean-
while the granules which were contained in the pollen grain pass
down through this tube, enter the ovary, and there form themselves
into cells, which, uniting together, form the ovule or germ of the
future seed, with its four protophytic cells, its albumen, and its
coverings, as I described when I started on my journey. This pro-
cess completed, the young cells are fed with the sugar, formed as in
germination by the conversion of starch — and which every bee knows
how to find ; they thrive, the seed forms and ripens, and again we
reach the point from which we started.

In taking a retrospect of the natural history of our wheat-grain,
we cannot exclude from it an expression of the highest admiration at
the beautiful adaptation of "vital force," which produces each part
of the plant, and prepares it for its designed function. Let us look,
for the moment, at one phase in the series alone. We have seen
that the leaf is only a modified portion of the stem, and that the
flower, with its pistil and stamens, and coloured leaves or corolla, is
only a modification of leaves. In this interesting feature of what

Fig. 9.

18 POPULAR ILLUSTRATIONS OF

is termed the morphology of the plant, we find an instance of a law
which pervades the whole of organised nature — viz., the adaptation
of similar means in the production of widely different results. And it
is a law which, as far as our reason can tell us, is one of necessity.
Were man, for instance, with his knowledge and experience, and
assuming him to have the artistic skill, called upon to make a plant,
he would form the roots and the stem ; he would then modify the
material of the stem into flat expansive processes, through which
the vital fluids of the body could circulate, and become aerated by
the atmosphere. He would then alter these processes into the com-
plex and beautiful arrangement by which the species would be
propagated. It would not be consistent with the unity and
perfection of the plan were he now to introduce new textures.
He would make use of the leaves, and would modify one into a
bract, another into a calyx, another into a pistil, another into a
stamen, and thus constitute a flower. And the necessity of this is
apparent,- for the flower has to be nourished through the medium of
leaves, and therefore on just the same plan throughout.

And so we find that Infinite Wisdom has adopted that which our
reason calls perfection in the creation and organisation of the world.
But He has done much more, for He has endowed created things
with a law by which they are not only perpetuated in time, but are
also adapted to the purposes of existence. Thus we see that, under
the operation of that law, the roots, the stem, the leaves, and the
flower of the plant act in perfect harmony with each other, and
seldom vary from their primitive form. If, however, man steps in
and alters the circumstances of existence, the law which is imma-
terial and cannot change, refuses to co-operate with a non-natural
condition of the being. Take a plant, for instance, out of its wild
and natural locality, and cultivate and feed it highly : it is charged
with a greater amount of nutrition than it was designed to assimi-
late, and we now see that remarkable change of the conversion of
the stamens of the single plant into the leaves of the corolla of the
double. But naturam expelles fared, tamen usque recurret. Take
away the excess of nutriment, and the plant will return to its
original form, the leaves will become stamens, and the flower single
again.

THE LOWER FORMS OF LIFE. 19

PART II.

THE PKOTOZOON.

CHAPTEE I.
THE PROTOZOA : THE GREGARINA AND INFUSORIA.

As the simple vegetable cell, the Protophyton, is the type upon which
all plants are constructed, so does the Protozoon represent the pri-
mitive simple cell, by the aggregation of which all animal structures,
whether flesh, bone, skin, hair, nail, feather, or scales, are formed.
The animal kingdom is divided into five great sub-kingdoms, viz. :

1. The Protozoa, comprising the lowest form of animal life — of
the Protozoon, in fact, in its simple unicellular character.

2. The Radiata, so called because they have a radiate form, like
the sea-anemone and the beautiful zoophytes formerly thought to be
flowers. The name, however, is faulty, inasmuch as animals like the
star-fish and echinoderm, which have a much higher organisation
and belong to a higher sub-kingdom, have marked radiate forms.
The difficulty has been fully recognised by naturalists. The term
Coelenterata, for reasons we shall see by and by, has on anatomical
grounds been applied to the group.

3. The Mollusca, so called because their bodies are soft, like
the oyster. This group includes the great mass of animals that are
protected by shells, or tunics of softer material. A great number,
however, like the garden slug, are naked.

4. The Annulosa, so called because the bodies are formed upon the
plan of segments, or annular divisions. It includes the echinoderms,
worms, crabs, lobsters, spiders, myriapods, and insects.

5. The Vertebrata, so called because each animal has a vertebral
column, formed of a series of bones termed vertebrae. It includes
fishes, reptiles, birds, and mammals.

With this necessary preface, we will now deal with the first and
lowest sub-kingdom.

THE PROTOZOA.

This group is represented by five classes of animals, all consisting
of simple cells, and therefore ranking in organisation nearly parallel
to each other. Naturalists, however, have placed them in the

c2

20 POPULAR ILLUSTRATIONS OF

following order, beginning with what they consider the lowest form :
1. The Gregarina, 2. The Infusoria. 3. The Rhizopoda. 4. The
Eadiolaria. 5. Sponges.

I shall have something to say about each of these classes when
their apparently unintelligible designations will become manifest ;
and first let us notice

THE GREGARINA (from grego, to congregate).

It will be better for me to say a few words here upon the dis-
tinction between animals and plants. And really this is a very
difficult question, and one by no means decided by naturalists ; for
although the most marked difference between the two organisms
is found in the evolution of oxygen and absorption of carbonic
acid by the plant, and the reverse by the animal, yet there are
exceptions even to this rule. Moreover, the rule itself does not
half help us in forming a differential diagnosis under the microscope.

Some naturalists have founded the distinction upon the possession
of a mouth and stomach by animals, on the larger amount of nitro-
genous principle in their tissues, and also on their possession of
sensation and voluntary motion. But, as I shall soon show, there are
undoubted animals which have neither mouth, stomach, nor loco-
motive or sensitive organs. Again, the ascidian mollusk contains a
large amount of cellulose, a principle closely allied to starch. Starch
is also found largely in the solid textures of man and animals, while,
as we have seen, nitrogen exists in great abundance in the gluten
of cereals and other plants.

The possession of sensation and voluntary motion is certainly
almost universal in animals, but it is by no means deficient in
plants, of which any one may satisfy himself by watching the move-
ments of Volvox globator and other low vegetable forms under the
microscope. In some of the Algse, also, there are distinct move-
ments observed in the granules which exist in the juices of the
plant. In the Confervae these granules are observed to move to-
wards a particular spot, where an aperture is formed, from which
they escape and move about in the surrounding water. Under a
high microscopic power these granules are seen to have
cilia or hair-like organs attached to them, by which
they move about in the water. They have the figure
as in margin.

After a time the cilia disappear, and the granule fixes itself
to the side of the vessel, and becomes elongated, thus :

It now forms a cell wall, and increases in growth by the
formation of other cells like itself.

The great class of Diatomaceae — a series of organisms whose

Ife:

THE LOWER FOEMS OF LIFE. 21

flinty remains form some of the most exquisitely beautiful objects
under the microscope, and of which I believe nearly two thousand
species have already been described by Dr. Greville and others — are
not allowed to be claimed by the botanists unchallenged. I remember
the late Dr. Trail, of Edinburgh — a man of very great information —
came to the conclusion that they were of an animal nature, because
in Norway there is known an earth called the "bread earth," which
in times of scarcity is eaten by the poor as a substitute for bread,
and which, when examined by the microscope, is found to contain
vast numbers of Diatoms.

Now it will be admitted there will be less force in Dr. Trail's
inference, when it is considered that plants alone have the power of
forming the material of animal structure — viz., proteine. This the
animal cannot form itself, and it becomes one of the cardinal
distinctions between the two great kingdoms of nature.

If, however, I am asked to give any distinct rules by which the
microscopical student may at once distinguish the protophyton from
the protozoon, I cannot do so. Our knowledge upon this point is
entirely based on the dicta of the authorities in science, to which,
however, as a rule, we may very safely defer.

Taking, therefore, the highest authorities as my guide, I shall now
draw your attention to an examination of the lowest known form of
animal life.

In the intestines of insects, worms, and mollusks, the microscope
will detect small cellular bodies moving about by means of undula-
tions of their cell walls. These are living animals, parasitical in,
and living upon, the absorbed nutriment taken in by the insect or
worm for its own special use. They have neither head, eyes, mouth,
organs of locomotion, digestion, circulation, nor sense. They are
simple cells, containing a nucleus and an albuminous fluid with
granules called sarcode. They move about by means of wave-like
undulations of their cellular bodies. Fig. 10 (p. 22), taken from
the "Icones Histiologicae" of the celebrated Professor of Anatomy
at Wurzburg (A. Kolliker), shows one of these minute organisms
largely magnified.

I have given only one of the forms of this singular animal, but it
is often round, sometimes oval! It is colourless and microscopic. As
to size, if we take a fine needle and make the smallest mark visible
to the naked eye, we should fail in giving any idea of its minuteness.
It is quite invisible to the naked eye. I do not find any measure-
ments given by authors. These figures, therefore, which illustrate
this chapter, are all enlarged from the microscopic high-power image
for the purpose of illustration.

Since the Gregarince were discovered and described by Dufour in

22

POPULAR ILLUSTRATIONS OF

the "Annal.de Sci. Nat." vii., 1837, down to Kolliker's " Icones
Hist.," 1864, they have been well examined by naturalists, and some
very curious features in their economy discovered. At first about
eighty species were named and divided into genera. It was, how-
ever, found that many of the forms thought to be specifically
distinct were only the different phases of the metamorphoses which
the animal undergoes in its reproduction. These changes I will
describe.

Fig. 10.

Fig. 11.

Fig. 17.

Fig. 16.

Fig. 10. — Gregarina nemertis (Koll.), highly magnified — a, nucleus, containing nucleolua —
6, cell wall — c, granular contents of cell.

Fig. 11. — Two Gregarinse united together.

Fig. 12.— The same, contracted.

Fig. 13.— The same, forming cell wall, and nucleolus disappearing.

Fig. 14. — Nucleus divided and enlarged.

Fig. 15. — Further division of nucleus, and formation of " cyst membrane " (d).

Fig. 16.— Same cell, containing " navicular "-shaped bodies, and band of division dis-
appearing.

Fig. 17.— Same, cell, containing matured larvse of Qregarinae, band of division and cyst
membrane entirely gone (alter Kolliker).

First, two of the elongated cellular nucleated creatures shown at
Fig. 10, having become obtuse at the extremity nearest the nucleus
(a), come into contact with each other, as shown in Fig. 11. The
extremities then contract, and the next transformation is shown in
Fig. 12, where it will be seen they have become firmlv united into

THE LOWER FORMS OF LIFE. 23

one body, still having two nuclei, and a band of division. In the
next change, which is observed in Fig. 13, it will be remarked that
the dark spot shown in the centre of the nucleus (Fig. 12) has dis-
appeared, and that the contents in each division are now surrounded
by a delicate inner membranous envelope, separating them from the
outer cell wall, and also the two divisions from each other. In the
next (Fig. 14) the granular matter will be found to have formed
itself into a series of distinct round-looking bodies, which in Fig. 15
are seen to have subdivided into a much greater number, while an
outer membrane (d) now covers the cell. In Fig. 16 it will be
noticed that the inner envelope has become thickened and con-
tinuous all the way round, while the globular masses in Fig. 15 have
become changed into navicular or boat-shaped bodies. In Fig. 17
the band of division is finally withdrawn, and we now have a cell
full of the boat-shaped forms seen first in Fig. 16. These are the
larvse, which, when mature, are set free by the bursting of the cell
(Fig. 17), and become developed into the perfect Gregarince.

Now let us notice the salient points in this beautiful series of
processes. We have, first, the union and mingling together of two
perfect gregarinids, then the formation of a cell wall, then that
marvellous division and multiplication of the nuclei, then the change
from the globular to the boat-shaped germs or larvae, the obliteration
of the division which separated the upper from, the lower part of the
cell, the liberation of the larvae and their development into beings,
lowly as they are, yet destined to occupy a place in the scale of
organised nature. And yet this creature can only be seen by the
aid of the microscope, and its home is in the intestines of worms and
insects !

It is most interesting, and well worth our while, to observe
attentively the changes which take place in these low forms of
animal life during their period of development. Not only do they
shadow forth much that is observed in higher forms of animal life,
but the changes themselves are very curious, and utterly incompre-
hensible to our limited faculties. Every movement and change
takes place with the most perfect order and regularity, and seems,
as Kolliker himself has remarked, to be under the direct operation
of the will of the creature. And yet how can we assign a will to a
speck of jelly containing a fluid and a few granules ?

The division of the nucleus, when viewed under the microscope, is
a most beautiful sight, each particle into which it separates forming
the nucleus of a new growth (Fig. 14), which takes up all the
granular matter seen surrounding the nucleus in Fig. 13. These
new growths again subdivide, and the product is the more highly
organised bodies seen in Fig. 15. Observe, also, that in this stage

24 POPULAR ILLUSTRATIONS OF

of the development a " cyst membrane " (d, Fig. 15, p. 22) is thrown
round the cell to strengthen it, and enable it the better to hold its
contents until they are entirely developed, when it disappears, and
the cell bursts.

This encysting in reproduction of these organisms is constant
throughout a class which Grant has called Cystodia, and of the three
orders into which he has divided this class the Gregarinea, as he
calls them, is the first. It is also characteristic of animal life, and
may be added to the distinctions between plants and animals. It is
worthy of remark, as showing the border ground between animal and
vegetable life occupied by these cells, that M. Bary, of Prague, has
lately demonstrated that certain forms of fungi belonging to the
Mycetozoa are most probably referable to the Gregarince. These
fungi are, in Grant's words, "composed of aggregations of simple
cells, commonly referred to the vegetable kingdom."

THE INFUSORIA.

If a small quantity of hay, grass, or other vegetable or animal
matter be covered with water and allowed to stand for a few days
exposed to the atmosphere, and a drop be then placed under the
microscope, it will be found teeming with life. Hence the animal -
culae which may be produced by infusing organic matter are called
Infusoria.

Their occurrence under the circumstances mentioned has given
rise to the theory now held with great pertinacity by M. Pouchet
and others of spontaneous or equivocal generation, which simply
means that the animal Protozoon may be produced and endowed
with life from the elements of dead organic matter. This doctrine,
however, which has been supported with great ability and careful
experiment by M. Pouchet, has been successfully combated by M.
Pasteur, who has satisfactorily proved the truth of the doctrine
hitherto held, that these organisms are produced from germs which
are always either floating in the atmosphere, or mingled with the
organic matter whose decay forms for them the " circumstances
necessary for their existence," at the time of which decay, and only
then, they produce the living creatures known as infusorial animal-
culae. The discussion between these inquirers, and a detail of the
experiments which each of them performed, have been published in
almost all the natural history magazines in this country during the
last four or five years, and it therefore is unnecessary for me to say
more upon the subject here.

There are few objects more interesting, and to the student more
startling, than the examination of a drop of water from a stagnant
ditch, or a basin in which vegetable or animal matter, such as a

THE LOWER FORMS OF LIFE. 25

dead oyster, has been allowed to decompose. Those who have not
microscopes may see all the Infusoria in Pritchard's translation of
Elirenberg's great work ; but half the charm is lost if they are not
seen alive. Their motions are so quick and graceful, their form so
varied, their habits so singular, that they who are unaccustomed to
microscopical investigation are always, when shown this sight, filled
with astonishment and delight. The scene is continually varying.
At one time you see a number of creatures of an oval shape, more
or less pointed or obtuse, dart across the field of the microscrope
like the shuttle of a weaver, rebounding when they come in contact
with each other or any of their companions, but generally making
good way. These are divided into many genera, such as Paramaecium,
Euplotes, Loxodes, &c. Then will be seen rolling along the globular
conf ervoid ( Volvox globator), coloured green, as a plant ought to be,
and containing many easily seen young volvoxes within it. Now a
waving, sneaking, leechlike-looking thing (Loxophyllum) will show
itself, followed by the trumpet-shaped Stentor. But stay; what
was that which suddenly seemed to be in and then out of sight
again in a moment ? Keep as still as a mouse, and you will observe
that you have got a bit of the root of duckweed in sight, and from
this root you will see gradually coming out, as it were, a stalk, and
then the end of the stalk will appear to expand into a cup-shaped
extremity, the edge of which is surrounded by hundreds of small
hair-like organs (cilia) which immediately begin to work about with
a motion so rapid that you can hardly see them. Eight, or ten, or
twenty, or more of these cups, each with its separate stalk, may be
observed : thus creating a current in the water in order to draw into
the same cup any other animalcules, which, whether, they will or
no, once in the current, like the unlucky boat over Niagara, are
carried away to their destruction, for the Vorticella nebulifera is
feeding. The slightest movement of the microscope, and quick as
lightning, every cup, by a corkscrew-like action of the stalk, is
drawn down to the root of the duckweed. If you watch them long
enough, you will find some of these cups are splitting in two —
each half forming a perfect cup — and as one stalk is too much for
two, one of them separates and goes into the world of waters on its
own account. There are many different species and genera in the
family of Vorticellina, all of which are interesting objects under the
microscope. But what is the object with revolving wheels ? It is a
"wheel animalcule," one of the Eotatoria, but it belongs to a much
higher class than our Protozoon, so we must defer all notice of him,
though one of the most beautiful and interesting objects seen through
the microscope.

26 POPULAR ILLUSTRATIONS OF

CHAPTER II.

THE INFUSORIA (continued}.

IN the early period of our acquaintance with the infusorial aninial-
culae a very erroneous idea of their structure was entertained by
naturalists. This was principally owing to the fact that Ehrenberg,
to whose investigations our knowledge of the vast number of species
was principally due, was not so good a comparative anatomist as he
was an observer. Hence the lowly infusorial animalculae were placed
in a much higher position in the animal kingdom than they can lay
claim to. Muscular power, nerves, a blood circulation, and a multi-
plicity of stomachs (hence their name Polygastricci) were assigned
to them, without any foundation in fact. They are unicellular
Protozoons. Before I make this obvious, let me say a word or two
about one or two parts of their organisation which they have in
common, and which will be frequently alluded to.

Sarcode is the term which has been assigned to the jelly-like sub-
stance of which the bodies of the Protozoa are formed. It has been
called liquid flesh. It is, however, the substance which supplies the
place of flesh in the lowest animals, and resembles it in chemical
composition, but differs in the absence of muscular fibre. It is
semi-transparent and variable in colour. It is insoluble in water ;
and, when dried, its physical characters are restored by immersion.
Its singular properties will be noticed as we proceed in the descrip-
tion of the Protozoa. All the bodies of the Protozoa, including the
Gregarinae, are formed of this substance.

Cilia are the minute hair-like bodies which fringe the oral aper-
tures, and in some instances all the surfaces, of the Protozoa. They
occur in both vegetable and animal structures, from the Volvox
globator up to man himself. They have very remarkable properties,
either as organs of locomotion, or as, by their rapid motion, the
cause of currents by which food is drawn into the mouths of
creatures otherwise unable to obtain it. On a large and familiar
scale, they are illustrated by the human eye-lashes. They are from
•02 to '00005 of an inch in length in the Protozoa, and their move-
ment is so rapid, that they are frequently invisible through the
microscope, anid their presence only inferred by the currents which
they produce. They move uniformly with regard to each other, each
bending from its base to its point at the same instant of time. This
motion ceases or commences in obedience to what appears to be the
will of the lump of jelly constituting the Protozoon.

Let us now take one of the best known forms of the Infusoria,
Paramcecium Bursaria, and with the aid of the cuts we shall be able

THE LOWER FORMS OF LIFE.

27

to get a very fair knowledge of the structure of the entire group.
Fig. 18 is a view of the animalcule as seen when looking down
through the microscope upon its back. Observe, first, the mantle of
cilia which covers its entire surface. These are its organs of locomo-
tion, and also, as just stated, the media by which it forms currents
and draws its prey within its grasp. Minute and delicate as are
these beautiful organs, my friend, Professor Alhnan, of the Univer-
sity of Edinburgh, discovered that the creature has imbedded in
its "cortical layer" a vast number of cells, of a peculiar con-
struction, called trichocysts, which the animal can burst at will,
and from which protrude a great number of extremely fine (even

d— :

Fig. 18. Fig. 19.

Fig. 18. — Paramxcium Bursaria, dorsal side (after Stein), magnified 300 diameters— a a,
contractile chambers — b, nucleus— c, nucleolus— d d, particles of food surrounded by a rim
of water -e, chlorophylle grains-/, cortical layer, on the outside of which is the
u cuticula " or outer covering, bearing (g) the cilia.

Fig. 19.— Diagrammatic section of Paramxtium Bursaria— a, the double line represents the
cuticula, or secreted outer envelope, carrying the cilia— 6, the cortical layer, passing through
which the urticating threads are seen. When the animal does not use them they are
inclosed in cells termed trichocysts — c c, the contractile chambers in the cortical layer —
d, the mouth — e, the "central sarcode," which, being thinner than that of the "cortical
layer," is continually circulating round the space it occupies, carrying with it the food.
It contains the nucleus, &c., as shown in preceding figures, which is, however, generally
attached to the cortical layer.

when compared with the cilia) threads, which are supposed to have
the power of benumbing its prey — a power well known to be
possessed by these threads in animals higher in the scale. Observe
now the shape of the body, and note that all the way round there is
a thickened border or edge, which consists first of an outward struc-
tureless covering, which is, in fact, an excretion from the body of the
animalcule. This is termed the cuticula, and the rest of the dark
border consists of sarcode, and is called the " cortical layer"
(Fig. 19). This cortical layer gradually becomes softer until it is semi-
fluid, and in this condition the sarcode fills up the rest of the body.

28 POPULAR ILLUSTRATIONS OF

Now let us examine the objects seen through the clear diaphanous
substance of the animalcule. First, notice the two clear circular
spaces marked a a, Fig. 18 (p. 27). These are termed the contractile
chambers or vesicles, which are observed to be continually opening
and shutting — that is to say, they are alternately visible and
invisible. Now these contractile chambers, or vesicles, or spaces, as
they have been at different times called, are a marked feature in the
structure of the Infusoria. They are observed to be connected with
channels having a communication with the outside of the body,
through which these chambers are alternately filled with and
emptied of water. Kolliker has shown this in a beautiful series
of figures in his "Icones Histiologicae," which I have copied
(Figs. 20-24).

Fig. 20. Fig. 21. Fig. 22. Fig. 23. Fig. 24.

Figs. 20-24 — Contractile chamber of Paramsecium in five successive stages (after Kolliker),
magnified 500 diameters— 20, the chamber or vesicle contracted, and the rays tilled with
water — 21, the first emptying of the rays and simultaneous filling up of the chamber —
22, the second filling of the rays — 23, the second emptying of the same, and probable
filling of the chamber— 24, commencement of the emptying of the chamber and after-
filling of the rays.

This water circulation is, no doubt, connected with the process of
respiration ; that is to say, it is the means by which oxygen sus-
pended in the water is conveyed to the interior of the animalcule,
and carbonic acid conveyed away.

And mark, this beautiful apparatus is one of the types upon which
this class of living beings is formed. We shall see by and by, in
the higher animals, many different modes of breathing ; but in none
shall we find an exact repetition of these contractile chambers and
canals. Now let us look at the two bodies marked b and c, Fig. 18
(p. 27). These have been named the nucleus (b), and the nucleolus (c).
But they do not represent parts equivalent to the nucleus and nucleolus
of cells. The body marked b is, in fact, the ovary, and c bears the
same relation to it as the pollen grain does to the ovary of the plant,
as we shall see by and by.

At d d notice particles which have been swallowed as food, sur-
rounded by globules of clear water, which was probably taken in
with the food. These globules were considered by Ehrenberg as
so many distinct stomachs, and upon this mistake was founded the
order Polygastrica, or " many stomachs." This, as I have already
stated, is quite erroneous. At e. and scattered all through the

THE LOWER FORMS OF LIFE.

29

interior of the animalculse, and carried into the fluid sarcode, is a
constant circulation from left to right ; round the general cavity are
numerous granules of chlorophylle, which give it a green colour, and
which we have seen before is the pigment of vegetable structure,
and is always floating about in water. Now let us turn the little
creature over upon its back, and notice what comes into sight as
shown in Fig. 25. At a we have the mouth, and at b the gullet —
but mark, no stomach. The gullet simply carries the food into the
bag, which is inclosed by the " cortical layer," and in which the
liquid sarcode circulates, carrying with it the particles of food,
chlorophylle, granules, &c.

a—

•c

Fig. 25.

Fig. 26.

Fig. 25. — Ventral side of Paramsscium Bursaria, showing — a, the stomach— b, the gullet or
oesophagus— c, the nucleus — d, the nucleolus.

Fig. 2G.—Paramiecium Aurelia (after Kolliker), dividing— a a, contractile chamber— 6, elon-
gated nucleus contracting in the middle c c, nucleolus divided, but the new ones still
connected with each other.

In Fig. 26 we have an illustration of one of the methods by which
Infusoria increase. The nucleolus divides into two, and each division
attaches itself to the ends of the nucleus, the latter becoming at the
same time elongated. The animalcule and nucleus are observed to
become thinner in the middle, and ultimately they divide into two
distinct animalcules, which again subdivide, and so increase and
multiply. It has recently, however, been discovered by M. Balbiani,
and confirmed by Stein and Kolliker, that the Infusoria are also
reproduced by the following means. The nucleolus (c, Fig. 18, p. 27)
represents the male part of the creature, just as the pollen grain
does of the plant ; while the so-called nucleus (b) is the ovary. At
certain seasons the nucleolus is observed to grow in size ; and in
this condition two animalcules become conjoined, as shown in the
Gregarinse, and, mingling together, the nucleolus of each division

30

POPULAR ILLUSTRATIONS OF

passes into the ovary of the other. Here, as in the plant, the germs
of future Paramaecia are formed in the shape of round bodies. These
become of an oblong shape, then covered with cilia, and in this
form are set free from the parent cells, and start on their own
account as young fry in the great struggle for existence to which
the nomad as well as the man is doomed.

But there are two other modes of propagation among the Infusoria.
To illustrate these singular phases in the life history of these lowly
forms of animal existence, let us examine the economy of the Vorti-
cellinae, considered by some as typical forms of the Infusoria. Fig. 27
is from a drawing of a group of Vorticella nebulifera, attached by
their stalks to a bit of the root of duckweed. They are seen in all
the positions they assume under the microscope, except that in which

Fig. 27.— Vorttcella nebulifera (highlymagnifled)— a a, unfolding - 6 &, retracting— c, dividing
— d. bell separated from stalk, and having a posterior circlet of freshly-developed cilia.

they simultaneously contract and draw themselves down to the root
to which they are attached. Their structure is not such as would
be inferred by the appearance of the group. Let us, therefore, fol-
low the history of an individual, say that one marked d, which is
seen to be falling away without a stalk. The bell has just been
developed by division, or fissiperation as it is termed — the process
described in Paramaecium. The division is completed at c, and c?
has just separated from the animalcule whose stalk it is represented
as bending. Note, first, that this cup or bell has a series of cilia
provided for it at the end opposite to the mouth. These are its
principal locomotive apparatus, and by their means it swims about
in the water. When, however, it finds a place suitable for its pur-
poses, it becomes attached thereto by this end, and the locomotive

THE LOWER FORMS OF LIFE. 31

cilia become gradually changed into a stalk, which, by growth is
developed into the singular elastic contractile organ shown in
Fig. 28 (h). The exact nature of this stalk has not yet been fully
made out. My friend Professor Bennett, of Edinburgh, considers it
contains contractile tissue, and that it is merely a prolongation of
one of the layers of the bell itself.

Be this as it may, this stalk is certainly a tube, which contains a
thin thread-like band, which I have shown in the figure at i in the
form it appears in the interior of the stem.

Now then, the stalk having grown to its full length, the animal-
cule may be considered as mature, and we are able to see through its
clear body all that is contained therein (Fig. 28).

Fig. 28.— Diagram of Vorticella—a a, the peristome — 6, the disc — c, the mouth— d, the gullet
— e, opening in gullet—/, contractile chamber— g, nucleus — h, stalk — i, contractile filament,
supposed to be the continuation of one of the coats of the animalcule.

First, however, observe the rim round the distal extremity of the
cup (a). This is called (from the two Greek words signifying
"about" and " mouth ") the peristome.. Note also that this peri-
stome does not carry the cilia. This is done by what is termed the
" disc," which is placed within the peristome, and has its outer edge
furnished with one or more circlets of cilia, which assume a spiral
figure. The mouth (c) is placed in a small space between the disc and
the peristome, and the cilia are observed to commence a little to the
right of the mouth and, going to the left, run once or twice round
the edge of the disc, and then terminate inside the mouth in what
is called the vestibulum.

Thus what appears to be the open mouth of the bell is closed in
by the disc, and the animalcule has the power of drawing this disc
inwards, when the peristome will contract and cover it in. It is
impossible to show the curious arrangement in a drawing, but the
above description will, I think, render it tolerably clear, with the
aid of the diagrammatic Fig. 28. Well, then, the action of these
cilia forms a current, which brings to the mouth other animalcules

32 POPULAR ILLCTSTKATIONS OF

upon which it pleases Vorticella to feed. But strange, yet true, this
mouth exercises a power of selection, and, by the assistance of small
non-vibratile cilia which pass through the mouth into the gullet, it
rejects all non-nutritious particles, and chooses soft eatable animal-
cules only. The food goes into the gullet, and, after remaining at
the bottom thereof for some time, it passes into the general cavity
through an opening at e. The nutritious parts are now dissolved in
the juices of the body, and the rest sent out by the same opening
through which it found admittance.

The contractile vesicle, nucleus, and nucleolus are shown, but the
changes in them are similar to those described in Paramaecium.
Now this animalcule may increase by fission ; now and then, but
not often, a bud grows out at the bottom of the cup, which is
developed into a perfect bell, and being provided with posterior
cilia, like d (Fig. 27, p. 30), goes through the same processes of
development which I have just described.

Fig. 29. Fig. 30.

Fig. 29.— Vorticella encysted on its stalk.

Fig. 30. — Acineta stage of Opercularia articulata (one of the Vorticellinoe) —a, dendritic
nucleus - 6, cyst — c, tentacles — d, enlarged stalk.

Strange as are these undoubted facts, there is one mode of repro-
duction stranger still. Instead of conjugating, dividing, or budding,
our Vorticella may adopt a still more complicated means of repro-
ducing its kind. It draws in its disc, as noticed above, and the
peristome contracting the bell becomes of an oval shape. It now
envelopes itself in a cyst, as we saw the Gregarinee do, which cyst is
a mere secretion from the sarcode body. It has now the appearance
shown in Fig. 29. It then pushes out tentacular appendages, the
stalk thickens, and it looks for all the world like a gutta-percha
elastic bottle, as shown in Fig. 30. No wonder that its best friends

THE LOWER FORMS OF LIFF. 33

failed to discover our beautiful bell in such a shape, and it was
therefore considered by grave classifying philosophers to belong to an
altogether different family, and a new genus, termed Acineta, was
formed, to hold the various forms of spiny bottle-shaped looking
creatures. Some of them choose to attach their stalks, or, having
no stalk, to develop one and become attached to each other, and
then a new genus, the Podophrya, was formed. Luckily, our little
Vorticella having developed a number of young germs within her
bristly bottles, the said bottles burst, and the young fry, being
watched by philosophic eyes, are found to be nothing more than
veritable Vorticellae !

Now, in all the changes which I have described in the different
parts of the infusorial animalcules — in the formation of their coats,
their cilia, mouths, gullets, contractile spaces, nuclei, and nucleoli —
it must be distinctly understood that I have not referred to a single
structure which is organised in the strict sense of the word. No one
has yet discovered anything like a membrane, or any of the struc-
tures by which the different organs in the higher classes of animals
are built up. All that is yet known about them is that they are
simply formed in every part, outwardly and inwardly, of the jelly-
like substance known as sarcode. That our knowledge upon this
subject is still limited I certainly do believe. These lower forms of life
have not received that attention from our English histologists which
they have done from the German and French. Professors Huxley,
Carpenter, Allman, and Greene, Dr. S. Wright, and Mr. Bowerbank
are, however, names of celebrity, and from them the Protozoa have
received much attention. I wish they would give us a work like
the "Icones Histiologicae " of Kolliker. Perhaps Dr. Beale will some
day turn his one-fiftieth objective upon this lowly race of beings,
and tell us what 2500 diameters will show him.

CHAPTER III.
THE EHIZOPODA.

TAKE a drop of water from any stagnant ditch, and place it under
the microscope. Disregard the hundreds of creatures which we
dealt with in the last chapter, and fix your attention upon that
shapeless mass which lies on one side of the microscopic field. It
looks like some extraneous substance which has stolen unbidden into
the arena of our studies ; but keep your eye notwithstanding upon

D

34 POPULAR ILLUSTRATIONS OF

that apparently inanimate speck of jelly, and presently you will
observe that it has motion. If your observation, however, happen
to be interrupted for ever so short a time, you will be surprised that
you see this thing no more. There is something there, indeed ; but,
instead of appearing like Fig. 31, it has assumed a shape perhaps
like that shown in Fig. 32 ; and while you fix your excited attention
upon this, it will alter before your eyes to the semblance of Fig. 33 ;
and again, ere you can express your wonder (if this is your first
sight), it will have changed to something like Fig. 34, and, with
equal rapidity, to a form like Fig. 35. Now, if you look for an
hour you will probably not see it assume the same figure again. It
is always changing, and hence has received the name of the Protean
animalcule. It is the Amoeba, and one of the typical forms of the
Ehizopoda — thus named because the so-called feet or pseudopodia
are pushed out from the body so as to appear something like the
roots of plants.

Fig. 31. Fig. 32. Fig. 33. Fig. 34. Fig. 35.

Figs. 31-35. — Forms assumed by Amoeba under the microscope.

Now, this Amoeba, which I have selected to illustrate the
Ehizopoda, has been designed to play a very important part in the
physical history of the world, as I shall show by and by. Agassiz,
the Owen of the United States, has, in his recently published
" Graham Lectures," taken the ground that, although the earlier
forms of animal life were created myriads of years before man, they
were, notwithstanding, formed with an evident reference to his
appearance on earth. I have held the opinion for some years, and
I have strong evidence in this direction to give in favour of our
little lump of sarcode — for it is nothing more. Dr. Carpenter, in
his "Introduction to the Study of the Foraminifera," published in
1864, by the Bay Society, thus speaks of the Amoeba : " It is a
particle of apparently homogeneous jelly, changing itself into a
greater variety of form than the fabled Proteus, laying hold of its
food without members, swallowing it without a mouth, digesting it
without a stomach, appropriating its nutritious material without
absorbent vessels or a circulating system, moving from place to place

THE LOWER FOEMS OF LIFE.

35

without muscles, feeling — if it has any power of doing so — without
nerves, and not only this, but in many instances forming shelly
coverings of a symmetry and complexity not surpassed by those of
any testaceous animals :" (pref., p. vii.)

Now, there are two divisions especially under which I shall
endeavour to illustrate the peculiar history of this singular creature.
First, those which are either naked or else invested with a covering
softer than that afforded by shells. Secondly, those which form,
and live in, the beautiful shells known as Foraminifera.

The first series are well represented by the Proteus-like Amoeba
found in fresh water, to which I have alluded above. It is, in fact,
the type of the family, and, having observed it changing its form, let
us now look at it while feeding. If you fix your attention upon the
creature, you will notice that some other animalcule or an atom of
vegetable matter will now and then come in contact with the body,
and seem to -be unable to get away again. In all probability this is
owing to an urticating power possessed by the Amoeba. Be this as
it may, its fate, if a living thing, is sealed. By a peculiar action of

Fig. 36.

Fig. 37.

Fig. 38.

Fig. 36.— Food passing into the Amoeba.— a, the food— 6, the nucleus— c, vacuoles or air

spaces— d, granules — e, ectosarc— /, endosarc.

Fig. 37. — Food breaking up into smaller parts in the interior of Amoeba.
Fig. 38.— Undigestible parts of food passing out through coats of Amoeba at a.

the protruded parts called pseudopodia, the object is pressed against
and through the outer covering or ectosarc, as it is termed, and then
through the inner envelope or endosarc into the interior of the cell,
called an Amoeba. The structure of the creature is simply two
coverings inclosing a softer portion of sarcode, having contents very
similar to those described in the Infusoria. Having thus been forced
through the sarcodous envelopes, the substance breaks up into
granules, which are sent round the fluid in the interior of the bag,
during which process all that is nutritious is extracted, and that
which cannot be assimilated collects on the opposite side, and makes
its way through the two coverings out again. These several events
are illustrated in Figs. 36, 37, 38.

D2

36 POPULAE ILLUSTRATIONS OF

The above process is thus described by Dr. Carpenter : " This
movement is effected by the protrusion of some part of the periphery
of the body into a pseudopodian process of greater or less elongation.
Towards this process, and usually for some way into it, there is a
current of the internal granular substance ; at the same time there
is a retraction of any processes of the like nature which might have
been previously put forth from the other side of the body, and a
reflux of the granular substance from these towards the centre ;
and by a continuance of this change the entire body is gradually
advanced in the direction of the new extension." MM. Claparede
and Lachmann think it possible there may be an oral aperture, of
which the lips might be applied exactly to one another, and only
open at the moment of deglutition ; and they support this opinion
by asserting positively that there is such an opening in an allied
forms to which they have given the name of Podostoma.

But this singular creature, while it is exactly similar to the figures
given above of Amoeba when in repose, has the power of propelling
" whiplike filaments " from the end of each footlike process, with
which it lashes the water in every direction ; and any animalcule
thus caught remains attached to the whiplike filament, which then
contracts into a spiral and disappears slowly into the pseudopodium.
An appearance something like a mouth is then described, into which
the particle of food is now drawn ; but I think the description as
given us by Carpenter will certainly apply equally well to the
extemporaneous manufacture of a mouth to order, as seen in the
true Amoeba ; and certainly, after what we know can be accomplished
by sarcode in the Infusoria, and as we shall see by and by in the
Sponges, we must not be surprised at its wonderful performances in
the Ehizopoda. This remarkable substance, called by Carpenter a
"protoplasm," does, in fact, seem to unite within itself some of
the powers which, in higher structures, we can demonstrate to
depend upon nerves, muscular fibre, organs of circulation, digestion,
and even of sense. It is held by many naturalists in the present
day, that this " protoplasm" is differentiated in the higher animals
into the several organs I have mentioned.

The first thing that strikes us as remarkable, when looking at a
drop of water through the microscope, is the ease and grace with
which the animalcules move about. This motion is due, we have
seen, to a beautiful series of organs termed cilia. Now these cilia
move at a rate which is inconceivable to the faculties of the observer,
and they do this under the direct operation of the will of the
creature, for they work or remain quiet as it chooses. Here, then,
we have motion, and the power of exciting or stopping such motion.
But still more remarkable, the next thing we notice is the exercise

THE LOWER FORMS OF LIFE.

37

of a special sense or its equivalent, viz., sight, for these animalcules
rarely hit against each other. A human being under the circum-
stances would be knocked about and killed ; but the little speck of
sarcode, only the 500th or 600th part of an inch in diameter, avoids
all collision, and moves about among the crowd in safety. Then we
have seen that there is a water circulation which aerates the sarcodal
juice — a process of digestion, and four or five different modes of
reproduction. All this, as far as we at present know, results from
powers inherent in this " protoplasm" or sarcode.

Fig. 39.—Lieberkuhnia Wageneri, magnified about 280 diameters (after Clapavede).

Now, the next example of the Ehizopoda which we come to will
show the powers of this sarcode in another light, for we shall
actually see it converting a portion of its own body into a net by
which it catches its prey. The examples of Amoeba we have noticed
belong to the naked division of the group. We will now deal with
a transitional group between the naked and testaceous forms, called
Eeticularia, from the fact of their being able to produce the net
alluded to. One of the most beautiful individuals of this group is
that discovered by M. Claparede, and called by him Lieberkilhnia
Wageneri, after two great naturalists. I have given a reduced copy

38 POPULAR ILLUSTRATIONS OF

of Claparede's figure of this creature at Fig. 39. It will be noticed
that a large branch of sarcode appears to grow out of the body of
the animalcule, and divide and subdivide until it attains the length
in some instances of ten or twelve times that of the body. When-
ever these rootlike processes or pseudopodia meet, they unite
together, and then a net is formed of considerable size. When the
prey of the animalcule, which may be a near relation or one of the
Algae, comes into contact with the net, it sticks there ; how it sticks,
or why, I do not pretend to say, but that it does so is quite certain,
and, whatever it may be, its race is run, for the sarcode net imme-
diately takes it in — not to show it hospitality, neither to draw it
down to its respected parent who formed it into a net, but actually
in the most selfish manner possible to digest it itself. And now we
find out in earnest that Mr. L. Wageneri is an arrant impostor, for
he has actually converted a part of himself into a net, which seizes,
devours, and digests its prey in that form, while he remains quite
still at the bottom of the drop of water. The digested food then
becomes common property, and feeds the general corpus of Mr.
L. Wageneri. This animalcule is 1 -400th of an inch in size ; with
its net, l-100thto l-40th of an inch. Now it will be found that the
outside skin or ectosarc of these Beticularia is harder than that of
the naked Amoeba. It is not at present, however, in any degree
like a shell covering.

But following out the gradual development of shell in these
creatures, without for the moment attending strictly to classification,
or stopping to discuss the question whether an Amoeba with long
processes is higher in the scale than those with short ones, let us
look at the next group which this mode of investigation will bring
before us. The curious-looking thing shown in Fig. 40 belongs to
the genus Difllugia, and here the body is covered with what is called
a " test " — the word " shell " being reserved for those made of cal-
careous matter. This "test" is thought to resemble the chitine
which forms the external skeleton, such as the elytra, of beetles. I
am, however, strongly inclined to the opinion that this is only
a guess, as we have no evidence that the " protoplasm " has
yet been differentiated into chitine. The pseudopodia, short and
stumpy, are seen in these species protruding in a supper-seeking
attitude from the mouth of the test. Fig. 41 shows an example of
another genus, Arcella, which carries its test upon its back. Note
here also the short stumpy pseudopodia possessed by this creature,
you cut off a small piece of the end from one of these organs, it
will become developed forthwith into a test-carrying Ehizopod, like
its respected parent ; and the same with Difflugia. And mark, they
never make a mistake — that is to say, the bit of Arcella never is

THE LOWER FOEMS OF LIFE.

39

developed into a Difflugia ; nor does the portion of the latter ever
become an Arcella. This is a much more important fact, as bearing
upon the great question of the origin of species, than appears at
first sight.

The stamp of individuality is affixed to the speck of sarcode by
its Creator for ever. We shall presently find the Amoeba among
the earliest animals in time ; first, in the oldest known rock ; then
a mighty architect in the secondary geological epoch ; and thirdly,
unaltered and unchanged in the stagnant ditch or the great ocean

Fig. 40.

Fig. 41.

Fig. 42.

Fig. W.—Vifflugm globosa, highly magnified (after Ehrenberg),— a, test— 6, pseudopodia.
Fig. 41.— Arcella vulgaris.

Fig. SZ.— Gromia oviformis, highly magnified (after Schultze). — a, test— b, diatom caught in
pseudopodia— c, sarcode covering outside of test.

of these our own days. After Arcella I would direct attention to
Fig. 42, which shows a typical form of the genus Gromia, sending forth
its long processes, and forming a net, just as we saw was done by
the magnificent L. Wageneri. Observe that the test is also covered
by an extension of the pseudopodial sarcode, and from this other
filaments are sent out.

40 POPULAR ILLUSTRATIONS OF

At b an unfortunate diatom has got caught, and it will be noticed
that the sarcode is concentrating [around him ; he will speedily be
covered in, digested, and his siliceous shield sent forth for the
examination of future Grevilles, who, many thousand of years hence,
find it in the field of their microscopes.

In the next chapter I shall deal with those species of Ehizopoda
which have the power of forming real shells, of calcareous or excep-
tionally of arenaceous texture, which are included under the term
Foraminifera — organisms of great beauty and absorbing interest.

CHAPTER IV.

THE EHIZOPODA (continued).

THE History of the root-like footed animalculae known as the
Ehizopoda, and of which I illustrated the typical forms in my last
chapter, is one of surpassing interest to the naturalist, the biologist,
and the geologist. More especially is this true with respect to the
group to which I will now draw attention.

THE FORAMINIFERA.

The simple sarcode Amoeba, as we have seen, have wonderful
powers of transformation. They can adopt most singular means for
securing their prey, and they are endowed with the power of
secreting an outward skeleton or covering to protect them from the
numerous dangers to which they must be peculiarly liable. The
latter power is exercised in its maximum in the Foraminifera, which
are covered with hard calcareous or arenaceous shells, moulded into
forms of great beauty, and containing internal arrangements of
wonderful complexity. In this group, too, we get out of the minute
microscopical series which have hitherto engaged our attention ; for
although some of the Foraminifera are as small as any animalcule
we have examined, yet they pass upwards gradually from such a size
to that of a shilling among living species, but much larger in those
which are fossil, while many of the most interesting specimens can
be gathered from seaweed or sand by means of a pocket lens only,
and placed in our cabinets. The real study of the Foraminifera is
an extensive one, for even Carpenter's splendid work, published by
the Eay Society, is only very properly termed an " Introduction to
the Study of Foraminifera." I cannot pretend, however, in this
little work to go at great length into the subject, but shall content

THE LOWER FORMS OF LIFE. 41

myself with, I hope, exciting sufficient interest to induce some at
least to pursue it further.

Until the last thirty years the Foraminifera were classed as
mollusca, and were placed with them in conchological works. In
1826 M. D'Orbigny, a celebrated French naturalist, published a mono-
graph upon the family, and was the first to bring them into anything
like scientific order, but he still regarded them as mollusca. It was
in 1835 that Dujardin, to whom we are indebted for many valuable
discoveries among the lower forms of life, particularly those assumed
by the protoplasm, to which he gave the name of sarcode, turned
the attention of naturalists to the fact that the shells of the Forami-
nifera, were secreted by the Amoeba. Subsequent investigations by
both Continental and British histologists have fully confirmed this
discovery, and the works of Williamson and Carpenter, published
by the Eay Society, have brought together and added to their own
most valuable investigations all that is known up to, I may say, the
present day about these most remarkable Protozoons. Other and
original investigators have, however, added much to our knowledge
of the Foraminifera, among whom Dr. Wallich in this country stands
pre-eminent.

The shells of the Foraminifera have three distinct types of texture.
They are for the most part calcareous ; in fact, Dr. Carpenter thinks
they may all be considered as essentially formed of calcareous
matter. Their appearance, however, is that of three distinct types
— first, those in which the shell has the external character and
glossy look of porcelain ; secondly, those in which it has a hyaline
or glassy appearance ; and thirdly, those in which it is formed of
sandy particles, which are agglutinated together by a peculiar
secretion from the animal, and into the composition of which some,
but little, calcareous matter enters.

The shells which exhibit these different kinds of texture are not
divided into groups by reason of their texture. In fact, many of
them are partly hyaline and partly porcelanous, or they may be the
former when young (Fig. 56, p. 42), and the latter when old (Fig. 55,
p. 42). They may be sandy in texture, as in Figs. 43, 57, and 63
(p. 42), but there are porcelanous and hyaline shells of the same
shape, and in the samegenus, as the spiral shown at Fig. 63 (p. 42).
In Figs. 51-54 (p. 42), the texture is what is called sub-hyaline,
that is, having a tendency to the porcelain form, which in Fig. 54
(p. 42) is seen in all parts of the shell, except the ridge and anterior
portion of the segments.

I have said that the creature that forms these shells is the
Amoeba. This is proved by dissolving the shell in weak acid, when
its occupant is found to be a cast of the shell, and to be nothing

42

POPULAR ILLUSTRATIONS OP

Figs 43-63.— Groups of Foraminifera.— 43, Orbulina univ ersa ; 44, Lagena vulgaris; 45, dittor
var. interrupta; 46, Entosolenia squamosa; 47, Nodosaria radicula; 48, Nodosaria pyrula ;
49, Dentalina legumen ; 50, Cristellaria calcar ; 51, Nonionina", Barleeana ; 52, Jeffreysii ;
53, N. elegans ; 54, Polystomella crispa; 55, Rotalina concamerata (mature) ; 56, ditto, young .
57, Globigerina bulloides ; 58, Bulimina Pupoides, var. spinulosa ; 59, Uvigerina pygmssa \
60, Textularia variabilis; 61, T.variabilis, var, difformis; 62, Miliola bicornis, var. elegans'.
63, Spirilina arenacea.

THE LOWEE FORMS OP LIFE.

43

more than the sarcodous animal we have demonstrated as Amoeba
(Fig. 67, p. 46). In by far the largest number of shells, viz., those
which are hyaline, their true character is also shown by the pseudo-
podia being projected through minute orifices or perforations in the
shell, as seen in Fig. 64, and hence the name of Foraminifera. In
the porcelanous group there are no foramina, and the pseudopodia
are emitted from the mouth of the shell, as seen in Fig. 65.

Such being the texture, let us now look at the forms which they
assume, I have selected as typical examples twenty-one of these
shells for illustration (Figs. 43-63). These will be admitted, I
think, to be very beautiful objects. They remind us, in fact, of
works which, as specimens of art, are endeared to the memory of
the classic scholar. We have in these bottles (Figs. 44, 45) the origin
surely of the Roman lachrymatory, in which the tears of departed
friends were supposed to be kept. They are clear as glass, looking
as like bottles in fact as they can do, as is shown in Fig. 66, in
which the animal is seen through the transparent shell, while Fig. 46
is hyaline everywhere except the central white parts of the hexagonal
reticulations on the surface, which are porcelanous. Now look
at Fig. 49. Who had the first start, the pea in making its pod, or
the Amoeba in making its shell ?

Fig. 64.
Fig. 64:.—Discorbina globularis (after Schultze).

Fig. 65.
Fig. 65.— Miliola tenera (after Schultze).

We will not now argue this abstruse question, although, of course,
the Darwinians will give it in favour of the pea ; for, irresistibly as
it were, the imagination rushes to the old cornu ammonis — which, in
very olden times, was thought to be like the ram's horns which
ornamented the statues of Jupiter (Fig. 50). Go on a little,
and when you see Fig. 51 you must, whether you will or no, think of
the fairy nautilus gliding with graceful beauty over the surface of

44 POPULAR ILLUSTRATIONS OF

the deep, deep sea, or the cornucopia which the fairies of ancient
Greece used to fill with flowers. In the words of Dr. Williamson,
when dealing with these shells, we may exclaim, " Imagination may
long revel amongst these lovely creatures, ever finding abundant
scope for the play of fancy ; and should any one still exist in this
nineteenth century who is disposed to frown upon such objects as
unworthy of serious study, let him submit to be reminded that in
nature, as well as in art,

A thing of beauty is a joy for ever."

Now the mode in which these shells have been formed has been
well studied, and is well known. It is the simplest thing in the
world, for it is nothing more in the great majority than a process of
budding. It is done in this wise : Suppose Fig. 45 (p. 42), which is
a Lagena, were to propel a bud from its base, which were to grow
straight downwards, and reach about half the size of the maternity
(Fig. 45), and then propel another bud, which also grew to half the
size of its mother, and so on, for two more instances — why it is quite
clear, that you would have a figure exactly like Fig. 47 (p. 42), which
is no longer a Lagena, but a Nodosaria. Now suppose that the second
node in Fig. 47 were an independent Foraminifer — and there are
many such — and it were to develop a succession of buds like those I
have described, which, instead of growing down straight, were to
deviate to the right or the left ; the shell, when completed, would
have the discoidal shape shown in Figs. 50-56 (p. 42). Or look at
the Figs. 58 to 61 (p. 42) ; suppose the largest segment to be the
original germ, and the others gemmae therefrom in the way I have
described, and the mode of formation of these shells will be quite
intelligible. A different mode of growth is adopted by the non-
porous group, represented by Fig. 62 (p. 42), the Miliolinae. In
these shells each chamber is of equal length and formed after the
fashion of a piece of thread round a ball. The orifice is therefore
alternately, as the bud is perfected, at each end of the shell. In
Fig. 63 (p. 42) there are no partitions, either outwardly or inwardly ;
the shell, which attains the size of one-fiftieth of an inch in diameter,
is a simple cylindriform tube, coiled upon itself on a horizontal plane,
and is perforated with numerous foramina, through which the pseu-
dopodia extend. Fig. 57 (p. 42) represents a curious family, in
which the buds have no communication with each other, though
attached by their external shells. Dr. Carpenter suggests that if
we imagine one of these prolonging itself in a spiral form, it would
become a shell like that seen in Fig. 63 (p. 42). If the sarcode
body, as stated before, be separated from the shell, it would in many
species be a cast more or less of each of the chambers, which freely

THE LOWER FORMS OF LIFE. 45

communicate among themselves (Fig. 67, p. 46). In others, this
communication is by no means so perfect, and we have seen an
instance above (Fig. 57, p. 42) where there is none at all. It is
observed that in those species of Foraminifera in which the shell is
perforated, the sarcode being able to obtain nourishment by its
pseudopodia, the segments are more independent, as it were, than
in those species in which the pseudopodia are projected from the
mouth alone (Fig. 62, p. 42, and Fig. 65, p. 43) ; while in others
the foramina in the shells are the orifices of a series of canals
which ramify through all the chambers, bringing the innermost
whorl into direct communication with the external world.

But the organisation of some of the Foraminifera is still more
complicated. Without going minutely into this most interesting
subject, I will give an example, the details of which may be easily
followed : Take a shilling into your hand, and place it with the
Queen's head (God bless her !) upwards. Now imagine that the
letters were carried all the way round the rim, and that instead of
the Queen's head the upper surface of the shilling were filled up
with circles of letters, each letter opposed to the space between the
letter of the previous circles (cabbage-planting fashion). These
circles would, of course, ultimately end in a single letter in the
centre of the shilling. Now imagine further that if each letter in
the outside circles were to send forth a canal towards the centre of the
shilling, this would strike the space between the letters of the next
circle in the middle. Well, let this canal be supposed to divide at
this point, and to send forth branches directly to the two letters
on each side. Suppose further, that the edge of the shilling had
circular openings, about one-third of its depth from the top, in the
sulci of the milling on the edge of the shilling, and that they were
the openings of canals which went directly to those between each
letter in the first circle on the top of the coin.

Now, instead of a shilling with letters, imagine a circular shell
having its shape and milled edge varying from l-30th to 7-10ths of
an inch in diameter, and each letter a lump of sarcode connected
with each of the others in the way I have pointed out by canals
containing sarcode, and that through each hole in the milled edge of
the shell there issued a series of pseudopodia, also formed of sarcode,
like those in Fig. 64 (p. 43), and you have an exact representation
of a compound animal, or series of connected Protozoons ; the whole
being nourished by the prey caught by the pseudopodia coming out
of the foramina in the rim, which animal, living in its compound
shell, is known as one of the genus OrUtolites (Fig. 67, p. 46).

This singular organism is developed by a series of buddings
from a " central disc," as Carpenter calls it, which is beautifully

46 POPULAE ILLUSTRATIONS OF

figured in all stages of the shell growth in his truly magnificent work
on these creatures. In the centre of each shell there is found a
single somewhat pear-shaped chamber (&, Fig. 67), and a larger one
immediately surrounding it.* From this chamber a series of canals
are sent off, terminating as shown above in a chamberlet, as it is
called, which is represented by the figures on my shilling ; and the
first zone being then formed, the pseudopodia enable the animal to
increase the shell outwardly until it attains in some instances, as I
have before remarked, nearly one inch diameter. It is possible, by
decalcification with a weak acid, to remove the shell, and leave the

Fig. 67.

Fig. 66.

Fig. GQ.—Lagynis Baltica (after Schultze), highly magnified. A, animal expanded, and
pseudopodia protruded from mouth— £, animal contracted into the bottom of shell—
a, mouth.

Fig. 67.— Decalcified sarcodous animal of Orbitolites— a, the sarcode which fills the canal
opening in the edge of the shell through which the pseudopodia are emitted— 6, the
central sarcode or amoeba forming the animal of Orbitolites— c, the segments of sarcode
connected with each other and with the central sarcode by the various canals. In the
shell the space occupied by these segments is called a " chamberlet."

sarcode animal in situ. It will then have the appearance shown in
Fig. 67. The arrangement of the canals and the individuals which
make up the compound animal is well shown. The pseudopodia
proceed, as I have described, from the annular passages between the
outer row of segments, as they are called. In due season these
pseudopodia will form another concentric zone — like that from which
the canal (a) proceeds — which will then, in. like manner, be trans-
ferred to the edge of the new formation ; and so the Orbitolites will
increase in size.

* I have not thought it necessary to give a figure of the shell, which is of
course an exact impression of Fig. 67. This must be borne in mind when I
am describing the chambers of the shell.

THE LOWER FOBMS OF LIFE. 47

This is the simplest form of Orbitolites ; there are others
found in large quantities in the dredgings on the coast of
Australia, in which the structure is much more complex. It does
not enter into my plan to give details of these forms. I have said
enough to give a general idea of how the Foraminifera are con-
structed. There is a great deal of most interesting matter contained
in Drs. Williamson and Carpenter's splendid works before mentioned,
and to them I must refer those who wish to extend their studies
of these lowly forms of life. The student has one advantage not
attained in the Protozoons I have previously dealt with, viz., the
Foraminifera are many of them large enough to be picked off sea-
weed or out of sea-sand, with the aid of a moderate lens, and
preserved in our cabinets for examination. But they will not be
found in any number on the shore. They live in deep water, and
sand or weeds for examination must be obtained in two or three
fathoms. The following is Dr. Williamson's directions for securing
specimens : " If the collector merely seeks dried shells for his
cabinet, indifferent whether living or dead, the process of floating
them is by far the most productive. A few pints of the sand must
be collected from beneath at least two or three fathoms of water, and
thoroughly dried ; it should then be passed through a conchologist's
sieve, or coarse net, so as to eliminate all the rough material. The
finer portions passed through the sieve must be poured into a bowl
containing cold water, and well stirred up, so that the whole may be
saturated. On being allowed to stand a few moments the more
delicate of the concamerated shells, rendered buoyant by the air
contained within their chambers, readily float to the surface, while
the sand and mud settle to the bottom. (Be careful at this stage to
burst all air bubbles on the surface.) A little manipulation enables
the collector to blow off this scum so rich in treasures, and the
addition of fresh water cleans them ; the creaming of the bowl
being repeated as long as any sediment or impurity remains. The
water may be now drawn off by a syphon, and the objects dried,
when they are easily collected for examination."

Dr. Williamson carries this process a step further, in order to get
the cleanest specimens. Sweeping the sides of the bowl with his
forefinger, he transfers them to a small evaporating dish, and boils
them in liquor potassae over a spirit lamp for some moments,
thus dissolving organic matter, and leaving the shells free from
impurity. The solution must now be poured off, and the shells,
which sink to the bottom, washed in cold water, and again dried for
examination.

When, however, the specimens are wanted living, Dr. Wil-
liamson points out that the mode of collecting them must be

48 POPULAR ILLUSTRATIONS OF

exactly the reverse of that above described. They must either,
where the coast sand is coarse and gravelly, be picked off the
corallines (whose zone, by the bye, is their especial home) or sea-
weeds. When the bottom is muddy and fine-grained, " the mud is
to be put into a vessel containing water, and well stirred up. The
fine inorganic particles are floated off, whilst the shells, from their
greater density and larger size, sink to the bottom ; a repetition of
the washings leaving them perfectly clean."

Such is a slight sketch of the Foraminifera in space. But they
are still more interesting in their fossil condition ; and as it is here
that their true position in the physical history of the world can be
best studied, I will devote my next chapter to a consideration of
"Foraminifera in Time."

CHAPTER V.
THE FORAMINIFERA IN TIME.

OFR path now lies for a season in the crust of the earth. We must
look into that mighty record of the past for proofs that the sarcode
Amoeba was a creature ultimately designed by Omnipotent power
to build up the solid portion of the world which man was destined to
people. It has been the province of very recent investigators to
prove that the Amoeba is the oldest of known fossils ; that it was the
architect unconsciously working away at a period so remote, that we
can only realise it in any intelligible form by comparing it with the
space we are told to think of, supposing the nebulous matter which
is resolved into stars by the high power of Eosse's telescope reveals
to us suns which are the centres of systems like our own. For years
past we have been told by geologists that the venerable relic known
as Oldhamia antiqua, figured and described in Mackay's "First
Traces of Life," and found abundantly in the Lower Cambrian
rocks, was the oldest of fossil forms. But geology is a progressive
science, and each year adds something to our knowledge of that
record which tells us of primeval fungi or most venerable Protozoa.
Sir Eoderick Murchison and Professor Sedgwick, having spent the
best part of their valuable lives in establishing the true position and
developing the geological history of the Silurian and Cambrian
rocks, find now other investigators are going beyond them, and
placing still lower systems than theirs among the fossiliferous strata
of the earth's crust.

THE LOWER FOBMS OF LIFE. 49

To those who are unacquainted with geology, I may remark briefly
that, although the entire solid crust of the earth has been calculated
by Mr. Hopkins to be not less than 800 or 1000 miles thick, there
are only about nineteen which are known to geologists as sedimen-
tary-fossiliferous rocks — that is to say, rocks which have been
deposited from water in different periods of the world's history, and
containing preserved within their beds the remains of some of the
living things which existed in those waters.

Now this nineteen miles of sedimentary rocks may be broadly
divided by the character of their organic remains, so as to represent
four nearly equal divisions. The first of these from above down-
wards— which is, of course, in order of age, the fourth period —
comprises — 1, all recent formations, including those strata called by
some geologists Quaternary ; 2, the Tertiary formations ; 3, the
Cretaceous, or Chalk group ; 4, the Jurassic, so called because they
are typically developed in the Jura Mountains ; 5, the Triassic,
corresponding to the upper new red sandstone, which is readily
divisible into three distinct groups — hence the name.

These strata are called Neozoic, because the life which is repre-
sented as having existed is "newer" than that which precedes it.
Till recently, and even now by many geologists, the term "new " is
confined to the recent and tertiary formations, under the term
Cainozoic ; while the secondary strata, from the chalk to the lias,
are called Mesozoic (middle life).

The third division comprises — 1, the Permian or Magnesian
Limestone ; 2, Carboniferous, or Coal measures ; 3, the Devonian ;
and these strata are called Upper Paleozoic (old life).

The second division includes — 1, Upper Silurian ; 2, Lower
Silurian ; 3, Cambrian. These form the Lower Paleozoic.

The first division or period, called till recently the Azoic (without
life), includes the oldest known sedimentary rocks, " the Laurentian,"
which are developed largely in Canada and the United States, and
are also found in Ireland, Scotland, and Devonshire. The above
arrangement will appear more clear from the following table :

50

POPULAR ILLUSTRATIONS OF

THE EARTH'S CRUST.

Fossiliferous
Strata.

1

b »

3 \

Fourth Period,
Neozoic
(New life). <
4-512
miles thick.

2.
3.

4

Tertiary. r- Pliocene, Miocene, Eocene...

Cretaceous /Maestricht beds, chalk, *
' (greensand, Gault,Wealden

03 C

1 £

™ .£
•1*]

3
J
)

1
)

i

>
1

Third Period,

5.

Triassic. — Upper, middle, lower Trias... ^
Permian. — Magnesian limestone . |

C/2 ^

)

Upper
Paleozoic >
(Old life).
4-458
miles thick.

8

Carboniferous -\ • ^^ ico
Devonian. — Upper and lower

4

o

Second Period,

" 9

Upper Silurian .,

1

Lower
Paleozoic '' \

10,

Lower Silurian

) ^

1

5-082
miles thick.

11

Cambrian

1

First Period,

19

PU j

Eozoic y
(Dawn of life)
5-670 miles.

13

r

* * *

o

1

<

Azoic
(No life).

Fundamental gneiss.

* * *

Granite.

a

2

Total known thickness of the earth's crust containing remains of organic
life, 19,722 geographical miles. If the present estimate of Laurentian rocks
being 90,000 feet thick turns out correct, this amount will be increased to
31-062 miles.

The estimate of the entire thickness of the earth's crust arrived at by Mr.
Hopkins, from data furnished by the effects of the sun and moon's attraction
as indicated by the rotation of the earth's axis and the precession of the
equinoxes, is from 800 to 1000 miles.

THE LOWER FORMS OF LIFE. 51

Now, beginning with the first fossiliferous period, which I propose
to term " Eozoic," as used in the above table, we find that these Lau-
rentian rocks, composed of quartz, slate, and limestone, forming in
many parts a beautiful veined green marble, occupy in Canada
and New York an area of 200 square miles, and have a known
thickness of 30,000 feet, and an assumed one of 90,000 feet, or, as
Sir William Logan has suggested, a thickness which " may possibly
far surpass that of all the succeeding rocks from the base of the
Paleozoic series to the present time, carrying us back to a period so
remote that the appearance of the so-called primordial fauna may
be considered a comparatively modern event."

This extraordinary formation has been recently proved to have
been formed almost entirely by Foraminifera. In other words, the
rocks are the remains of the shells of one of these animals, to which
the name of Eozoon Canadense has been given. This discovery, one
of the most interesting and important that geological science
has afforded us, was made by Sir William Logan, the Superintendent
of the Canadian Survey, and Dr. Dawson, the Principal of McGill
College, Montreal, guided by the information given them in Dr.
Carpenter's " Introduction to the Study of Foraminifera." The
details of the subject have been worked out with great care by Dr.
Carpenter himself, who published in the Intellectual Observer for
May, 1865, a most valuable and interesting paper, illustrated with
coloured and tinted plates, giving the history and showing the struc-
ture of this interesting fossil. To this memoir, and to one by Dr.
Eupert Jones, in the Popular Science Review for April, 1865,
and also to the papers of Dr. Dawson in the Journal of the
Geological Society, vol. Ixxxi., page 51, and of Sir W. Logan, in
page 48 of the same journal, I must refer those who wish to know
more than the limits of this work will permit me to say.

The Amoeba which formed the shell of the Eozoon Canadense in
those ancient waters was at least twelve times the size of any known
living species of the present day. And if you will be good enough
to refer back to my illustration of Orbitolites in the last chapter, and
imagine it to be a foot in diameter, and thickened proportionately
by placing one disc above another, you will obtain for all practical
illustration an idea sufficiently comprehensive of the representative
of the oldest living thing in the history of the world. And should
you ever hereafter be sailing on Lake Huron, or wandering among
the Canadian scenery watered by the St. Lawrence, it will be as well
to bear in mind that for that portion of the earth's crust we are
indebted to the labours of myriads of amcebiform creatures who
have left their remains as a mark of the service which they have
done in carrying out the great scheme of nature.

E2

52 POPULAR ILLUSTRATIONS OF

It is not known as yet if any other animal lived in those ancient
seas. On this subject the stone book is silent. There is, however,
no decided proof that other animals may not have existed coeval
with the Eozoon, although their remains are not found in the
Laurentian rocks. They may have been destroyed by the heat, which
metamorphosed the sediment of those seas into Labrador felspar,
hypersthene, crystalline limestone, and beautiful green veined
marble, but which left intact the cast of the Foraminifera, and so
perfectly that the fossilised pseudopodia may be seen like tufts of
silver wire radiating through its canals and chambers.

For the time being, then, at least, the Eozoon Canadense must be
considered as the oldest example of organic structure which the
records of geology have revealed to us ; and we must receive as a
fact of science that the lowest known sedimentary strata, for the
depth of from four to sixteen miles round the earth, have been
formed by the lump of jelly called the Amoeba. The student will
note that although these Laurentian rocks have only been observed,
say, in North America, Ireland, Sweden, &c., yet the geological
inference is that they would be found to occupy the same position
in all other parts of the world if the more recent formations were
removed. Thus, were I to bore into the crust of the earth at
Colchester, I should expect, at a distance of 13 J miles, to come
down upon the Laurentian rocks. At the time of their deposition it
is probable there was no land anywhere on the face of the globe,
which was one vast sea until the disturbing forces of central heat
from time to time kindly upheaved masses of land, which in his own
time the Creator peopled with living things.

There is something truly practical and satisfactory in the revela-
tions of a science which shows to us how gradually the crust of the
earth was built up, and how far down that vista of time, in which
the imagination may revel in awe and wonder, those mighty pre-
parations were begun which culminated in the creation of man
himself.

In the second or Lower Paleozoic period, Foraminifera have been
detected by Ehrenberg in the green grains which occur in the sand-
stone near St. Petersburg ; and, what is remarkable, there are many
of them referable to genera — if not species — now existing in our seas.
But the Foraminifera are not now found alone, on the contrary, they
are associated with animals belonging to all the other sub-kingdoms.

There are no less than nine classes of animals found in the strata
immediately above the Eozoic ; but then we cannot now, as we did
yesterday, reason upon these animals as existing in the first dawn
of life. The discovery of Eozoon Canadense makes the fauna of
the Silurian system, comparatively speaking, modern, although the

THE LOWER FORMS OF LIFE. 53

creatures comprised therein, existed in seas whose deposit, five miles
in thickness, is now at least nine miles more from the surface of
the earth.

In the third geological period the Foraminifera are still found at
work. In the carboniferous limestone there are beds formed
entirely by a genus called Fusulina, which seems to have come into
being and gone out of it in this period of the earth's history, as it
is no more found in its crust, or in the waters of our time.

As the name implies, these Fusulina are spindle-shaped, as shown
in Fig. 68, which is a cast of the chambers of the fossil. If cut
transversely across, a section will show its internal structure, as seen

Fig. 68.— Cast of the chambers of a Fusulina of simple type (after Ehrenberg) - a, median
segments— 6, alar prolongation.

Fig. 69. — Transverse section of the centre of a Fusulina (after Carpenter), showing c c c, the
principal chambers— a, the communication between the chambers -6 b, dark spots indi-
cating the origin of the alar prolongation (6, 68).

in Fig. 69, which is very similar to that of Nummulites, a genus
existing in enormous numbers much more recently. Two other
genera of Foraminifera are also found associated with Fusulina in
these carboniferous limestones, viz., Eotalia and Textularia, both of
which have many living representatives in our own seas, and
examples of which were included in my last chapter (Figs. 55, 56,
60, 61, p. 42).

At the end of the third geological period (see table) the form of
life appears to have undergone a great change, as we shall find more
particularly by and by. In the Lower Paleozoic, crustaceans reached
the highest amount of development, forty to every mile of rock. In
the Upper Paleozoic, fishes commence that remarkable numerical
development which reaches its highest point in the Jurassic — 270
per mile. Reptiles, but little known in the Paleozoic, make a
wonderful advance in the Neozoic, and attain their highest range in
the Triassic — over 90 per mile ; whilst mammals, commencing in
the Jurassic, where they are represented by seven species per mile
of rock, disappear entirely in the Cretaceous, and in the Tertiary are
found in the proportion of 34 to every mile of rock. There is thus

54 POPULAE ILLUSTRATIONS OF

altogether a great increase in the number of species in at least three
out of four of the classes I have mentioned in the Neozoic period.
But they not only increase in number, but in diversity and character.
Thus, any one seeing a Paleozoic fish or reptile, who is acquainted
with the subject, would recognise it from any part of the world as
such, but he would have a difficulty in separating those found in one
part of the world from those found in another ; whereas, as Professor
Haughton remarks, " in the Neozoic period each bed of rocks and,
I may add, each particular country, has its peculiar and characteristic
fossils, which are easily distinguished from fossils of other parts of
the earth formed during the same time."

With the Foraminifera, however, there has been but little change
in time. Messrs. Rupert Jones and Parker have described a bed of
clay at Chellaston as being almost entirely formed by the genus
Eotalia. This clay belongs to the Upper Trias, and we have just
seen that the Eotalia were associated with the Fusulina in forming
the Russian limestone in the Coal period. The same shells are
found in the Jurassic and Cretaceous systems, and are very abundant
in the crag on the Essex and Suffolk coasts. My figures were from
species existing in our own seas. The genus Bulimina is also found
in the Upper Trias and all subsequent strata. It occurs abundantly
in our seas, and I figured recent species of it in the last chapter
(Fig. 58, p. 42).

It is, however, in the Cretaceous group of strata that the Fora-
minifera begin to appear most abundantly. It may surprise many of
my readers when I tell them that the chalk cliffs throughout the
world consist mainly of the remains of Foraminifera. We cannot go
when we will and examine the stupendous Laurentian rocks, but we
can visit our chalk cliffs at Dover, or wander over our Sussex downs ;
and we can also realise the great use to man of chalk, when we see
our farmers spreading it upon their stiff clays ; and we can without
much trouble follow the " white hills " into Ireland and Spain,
France and Greece, for an extent of 1140 miles. We can follow
them from the south of Sweden to Bordeaux for 840 miles, and we
can measure these cliffs, and find them to have a thickness of from
600 to 1000 feet ; and then we can sit down in some snug corner,
and smoke our pipes, and ponder upon the wonderful fact that all
the most important parts of our earth's crust have been built up
by an animal, sometimes so small as only to be seen through the
microscope — a creature without muscle, bone, nerve, or blood vessel
— a mere lump of jelly !

But our inquiry is not yet over, for we have been into Egypt and
seen the Pyramids. "What of that?" I can fancy I hear one of
those sceptics, who never will see anything in anything, cry out,

THE LOWER FORMS OF LIFE. 55

" What of that ? We have you there. You do not mean to say
that your ' what-d'ye-call-'em ' built up those splendid monu-
ments?" Stay awhile, my friend, and it may do your scepticism
good to listen for a moment. My " what-d'ye-call-'em " did more
than build the Pyramids — they made the stone ! If you doubt this,
take a trip there next summer, and you will find the stone composed
of vast numbers of rounded discs, which were described by the old
writers as fossilised lentils used by the workmen who built the
Pyramids, and thought to be so until Strabo pointed out that it
could not be true, for there was a hill at Amasia, in Asia Minor —
where he lived — stretching out into a plain entirely composed of
similar lentil-like bodies (Geog., lib. xvii., p. 808, Paris, 1620).
And this has been proved correct by modern geologists, as we are
told by Dr. Carpenter that M. Tchihatcheff had brought from
Amasia splendid specimens of the well-known Foraminifer — Num-
mulites — so called from its " money-like " appearance ; for if you were
to cover a shilling on both sides with a layer of smooth calcareous
matter, you would make an exact representation of the fossil Num-
mulite.

I began this history of the Foraminifera in Time by a statement
which looks more like a fairy tale than a strict scientific fact. I
went back into the " dawn of life," and showed how the Amoeba had
built up rocks of marble hundreds of miles in extent on our earth's
surface, and of a thickness known to be five, assumed to be fifteen
miles. I shall close it by an account still more remarkable, viz., a
brief sketch of the history of the Nummulite.

If you will look at the geological table, you will observe
that the second group of strata (the Tertiary) is divided into
Pliocene, Miocene, and Eocene — expressive of their position in
time.

Now, at the beginning of the Eocene period, and contempo-
raneously with the London clay and Paris basin formation, we first
observe the appearance of the Nummulite. It reached its highest
point of development about the middle of the Eocene period, when
at least fifty species are known to have existed. It then began
suddenly to decline, appeared in less and less numbers in the later
Tertiaries, and in our seas only a single species is known to exist.

But in the period above indicated this little Foraminifer had
formed beds of enormous thickness and great extent in the crust of
the earth. Some idea of these extraordinary strata — known as the
Nummulitic limestone — may be gathered from the following extract
taken from Professor Haughton's " Manual of Geology," pp. 176
and 177 : —

" The geological distribution of Nummulites is most remarkable,

56 POPULAR ILLUSTRATIONS OF

as they are found along the entire line of mountain chains from the
Pyrenees to Thibet, and occur at all altitudes, from 8000ft. and
10,000ft. in the Pyrenees and Alps, to 15,000ft. in the Himalaya
Mountains ; they form a geological zone, stretching W.N.W. to
E.S.E. from 10P W. long, to 55° E. long., having a width of 1800
miles. Further to the east it narrows considerably, but the entire
length from W. to E. embraces 98Q long., and its breadth from
N. to S. ranges from the 16th to the 55th degree of north latitude.

" The Nummulitic limestone surrounds the entire border of the
Mediterranean Sea and of the Black Sea. It constitutes a large

portion of Egypt and of Asia Minor It is found in the

elevated regions of the sources of the Tigris and Euphrates, and
extends from Upper Armenia to the Persian Gulf. It also stretches
eastward from Armenia, along the valley of the Araxes, by the
chain of Elburz and the plateau of Iran, as far as the mountains of
Cabul and the Punjaub. It completely surrounds the valley of
Cashmere, and rises in the chain of the Himalayas to a height of
15,996ft., from which altitude it descends on the south-east of the
chain along the right bank of the Indus, forming the lower hills of
Beloochistan. Still further to the east it is found in the mountains
of Kossya, between the Brahmapootra and the plains of Bengal."

Professor Haughton says that Nummulites are not found in
America or in the southern hemisphere ; but this statement is not
quite correct. The species of Foraminifera are not well defined ;
and a closely-allied form, Orbitoides — which may be taken as not
differing more from Nummulites than species of the New World do
in general differ from those of the Old — forms an immense bed of
rock in Alabama, which is called in America "Nummulitic lime-
stone."

I need say but little more to prove the important agency assigned
to the Amoeba in building up the crust of the earth. In all this
there is a vast proof of the Design with which this lowly organism
was created. Take away the Laurentian rocks, and the chalk, and
the Nummulitic limestone, and the crust of the earth would tumble
to pieces. And yet they were formed by a lump of jelly that could
only have the blind instinct of self-support and self-preservation.

And the same Design is being carried out in our time for the
probable creation of a future world, in which Man himself may be
the most important fossil.

The bed of the Atlantic Ocean, even at a depth of two miles, is
covered by ooze teeming with Foraminifera, ninety-seven per cent,
of the soundings at the above depth being found by Capt. Dayman
to consist of Globigerina. They are principally found in the Gulf
Stream, and follow it in its course. Does this indicate a future

THE LOWER FORMS OF LIFE.

57

group of hills or mountains having such a range ? The coasts of
Australia are crowded with living Foraminifera ; in fact, they are
found in the soundings of most tropical seas, and the greater the
depth, as a rule, the larger the specimens. They occupy fifty per
cent, of the ooze in the deeper waters of the Mediterranean, Adriatic,
Bed Sea, Canaries, West Indian Islands, east and west coasts of
South America, St. Helena, and Isle of France.

70

70a

71

Fig. 70. — Nummulites complanaia, with a portion of calcareous covering removed.
Fig. 70a.— The same seen edgewise.

Fig. 71. — Three separate cells, showing the minute opening (seen as three white dots in the
cut) by which they communicate with each other (after Haughton).

Fig. 70 gives a representation of one of the most abundant species
of fossil Nummulite, with a portion of the calcareous shell removed
to show the internal structure, which, it will be observed, consists
of a succession of cells, placed as in Orbitolites, concentrically. In
Fig. 70a the bevelled edge is shown. In Fig. 71 the small openings
through which the cells communicate with each other are seen.

Fig. ll.—Nummulinaplanulata (recent) ; diam. one-twelfth to one sixteenth of an inch.
Fig. 73.— Same seen edgewise (after Williamson).

Figs. 72 and 73 represent the only known species of Nummulite

58 POPULAE ILLUSTEATIONS OF

existing in the present seas. It has been found at Portsmouth and
Scarborough, and is considered by Dr. Williamson identical with
fossil shells found in the Tertiary formations which were deposited
in the tropical seas, inhabited by "the gavial, sea-serpents, and
gigantic sharks."

The history of the Foraminifera is a part of that of the earth. I
have in this paper endeavoured to show how intimately the study of
.animal life is connected with those higher generalisations upon which
the science of geology is founded. How much is our interest
heightened in that drop of water under the microscope, and that
Protean lump of unsymmetrical sarcode called the Amoeba, when we
associate them with the physical architecture of the world, and the
forethought and design of that world's Creator !

CHAPTEE VI.
THE EADIOLAEIA.

FEW people who have not made science a study ever heard of the
Eadiolaria. Many even among the learned know little about a group
of animals of which we have only recently known anything at all ;
and yet we find them placed by Kolliker higher in the scale of being
than the creatures which form the shells of the Foraminifera. This
exaltation does not arise, as it well might, from the exquisite beauty
of their form, but rather that in the Eadiolaria there is, for the first
time, a departure from the unicellular character of the organism.
The Gregarinidae, the Infusoria, and the Ehizopoda, properly so
called, all consist, in their mature form, of single cells. They are
Protozoons — simple, as in the Infusoria, or compound, as in the
Orbitolites among the Foraminifera.

It is true that, as Kolliker remarks, originally all the Ehizopoda
are formed by a union of many cells, and yet each mature individual
contains its cellular nucleus only.

On the other hand, the Eadiolaria consist always, and without
exception, distinctly of a great number of cells, or Protozoons, and
so they lead us a step upwards in the scale of living things.
Kolliker fortifies his opinion by other reasons.

For our knowledge of the Eadiolaria we are, in reality, indebted
to Professor Huxley. Ehrenberg, it is true, was first in the field,

THE LOWER FORMS OF LIFE. 59

but to Professor Huxley is due the credit of bringing them promi-
nently into notice in the year 1851. Since that time they have
been studied by Mtiller, Claparede and Lachmann, Carpenter,
Kolliker, and others.

Mr. Huxley, in his paper ("Annals and Magazine of Natural
History/' Second Series, December, 1851), thus describes the locus
in quo of the Radiolaria : " In all seas, whether extra-tropical or
tropical, through which the Rattlesnake sailed, I found floating at
the surface the peculiar gelatinous bodies which are the subject of
the present communication. They were the most constant of all the
various products of the towing-net, which was rarely used without
obtaining some of them, and which sometimes for days would
contain hardly anything else." And he thus describes their nature :
" The Thalassicolla (thalassa — the sea, kolla — jelly, glue) is found
in transparent, colourless, gelatiniform masses of various forms —
elliptically elongated, hourglass-shaped, contracted in several places,
or spherical, varying in size from an inch downwards ; showing no
evidence of contractility, nor any power of locomotion, but floating
passively on the surface of the water."

Professor Huxley's excellent paper was written fifteen years ago,
and he says : " The extreme simplicity of structure of these creatures
was more puzzling to me than any amount of complexity would
have been. The difficulty of perceiving their relations with those
forms of life with which I was familiar gave me rather a distaste to
the study of them, and, as I now perceive, has rendered my account
of their organisation far less complete than I could wish it."

Since this paper was written some points which were obscure to
Mr. Huxley have been cleared up, as, for instance, their power of
contraction. Professor Kolliker (Icones Histiologicae) writes : " The
Radiolaria are, in all probability, a series of many-celled animals,
the bodies of which consist of the contractile substance by which
the Rhizopoda are characterised, and, like them, having similar
pseudopodia. Peculiar to the Radiolaria is a capsule in the centre
of the contractile body, and the appearance, both in this capsule
and throughout the body, of many distinctly cellular elements.
Many Radiolaria possess a peculiar skeleton of a needle-like spiculee
of flint, and, more rarely, of an organic horny substance, similar in
consistency to sponge."

Upon these grounds, then, this distinguished histologist has placed
the Radiolaria above the Foraminifera in the scale of living things.

And what, then, are these Radiolaria ? I will answer this ques-
tion by quoting a passage from the able review of Kolliker's work
in the Quarterly Journal of Science, vol. ii. p. 534 : —

" And what exquisite forms do these Radiolaria exhibit ! we feel

60

POPULAR ILLUSTRATIONS OF

sure that their beautiful shapes have only to be seen by our micro-
scopists to make them forget Diatoms and Desmidiae in their anxiety

Fig. l±.—Eucecryphalus Schnltzei (magnified 150 diam.).— The whole animal living. The
central capsule with the middle of the concave side of the silicious shell shown, deeply
cleft in four unequal parts containing very small yellow cells.

Fig. 75.— Thalassicolla pelagica (magnified 15 diam.). — The animal alive. The outer part
consisting of numerous cells containing yellow bodies. The central capsule has oil
globules round the margin, and a dark proto-plasmatic inner vesicle.

to possess them ; for, along with the beautiful cases of these,
they combine all the attractions of living and moving beings, and
their interest is by no means confined to their external coverings.

THE LOWER FORMS OF LIFE.

61

Some of them represent globular groups of pearls, with a brilliant
central gem of more solid consistency, the whole emitting bright
rays (pseudopodia) in every direction ; and, on examining the consti-
tuent globules, each one is found to be more or less highly organised
(Fig. 75). Others are still more beautiful and interesting. One,
for example, resembles a conical Japanese hat of honeycombed silex,
bristling all round the rim and on the apex with spikes and harbour-
ing in the crown of the silicious fabric the multicellular animalcule,
from which numerous rays are projected (Fig. 74). Another is
a perfect hollow silicious sphere of filagree, also honeycombed, and
in the centre floats a beautiful sun, whose rays penetrate the

Fig. !§.— Heliosphcera inermis (magnified 300 diam.). — The whole animal alive. The central
capsule is seen to contain a vesicle one-third its size, through the "honeycomb" of the
shell The fine pseudopodia emanate from the sarcode of the central capsule.

open framework of the globular case (Fig. 76) ; and a fourth — more
exquisite, perhaps, than any of the preceding — might serve as
one of the insignia of some noble order, for it presents the appear-
ance of a jewelled star. The central portion is the hyaline animal-
cule resembling a globular pearl in appearance, from which project
silicious rays, some lance-shaped, some straight, and all meeting
within the central globe (Fig. 77, p. 62). There are many more such
forms, varying in the shape of the central soft portions, or in that of
the radiating silicious skeleton, or of the surrounding casework ; but
all are more or less graceful and elegant, and the delineations of
them in the present work have only to be seen to render them eager
objects of search and favourite subjects for investigation."

G2

POPULAR ILLUSTRATIONS OF

Fig. 77.—Acanthostaimts haxtatiis (magnified 300 diam.).— Whole animal living. Shell with
twenty spines of different sizes. The central capsule from which these emanate is filled
with yellow cells. The pseudopodia radiate from the safcode of the central capsule.

Fig. 78. — A. purpurascens (magnified 150 diam.) — Whole animal dead. The bi-convcx four-
lipped central capsule contains many yellow cells and red pigment granules.

Let it be borne in mind that to the unaided eye these lovely
forms exist only in the form of lumps of jelly, floating for miles on

THE LOWER FOEMS OF LIFE.

the surface of the sea. It is not until placed under the microscope
that they present the appearance as shown in the figures.

Fig. 79. Fig. 80.

Fig. IS.—Physematium Millleri (magnified 15 diam.) —The whole animal dead.

Fig. SQ.—Collosphcera Huxleyi (magnified 300 diam.) —A whole colony alive. In the middle
a large alveolus, surrounded by a sarcode net, within which are smaller alveoli. In the
central capsule, which represents the parent animal, there are observed one or two balls
of oil. The larger cells covered with a transparent shell, the smaller ones naked. Out-
side the young brood, among the rays of the pseudopodia, a number of small yellow
bodies, supposed to be germs, are observed. (All after Kolliker.)

Kolliker divides the Radiolaria, as far as they are at present
known, into thirteen genera and many distinct species, and their
discovery, as I stated before, is quite of recent date. Their great
beauty will, no doubt, make them a favourite subject of investiga-
tion with the histologist. They form a ready transition to the last
— and, according to Kolliker, the highest — division of the Protozoa,
which I now proceed briefly to notice, viz. :

THE SPONGES.

I say, to notice briefly, because we have a recent classical and
exhaustive work upon the subject, to which naturalists can
readily refer, viz., " The Monograph of the British Spongiadae" by
Dr. Bowerbank, the first volume of which has been published by the
Bay Society. The subject has also been illustrated by many papers
in our popular publications.

But I do not wish for a moment to detract from the great scientific
interest which is attached to the study of the Sponges. On the
contrary, I think there are few objects in natural history whose life
is better worth recording than that of a Sponge.

64 POPULAR ILLUSTRATIONS OF

What, then, is a Sponge ? " What I use in my bath every
morning," answered an impertinent person who was looking over
my shoulder when I was writing the question.

But this self-evident answer, like many other utterances, is only
half true, for a Sponge is a great deal more than that when alive.
Place the Sponge on the table before you and you will notice that it
is covered with openings of various sizes, all leading to passages
in the interior. Now, these passages, which tunnel the whole
structure, are lined, when the Sponge is alive, with a more or less
extensive layer of sarcode, which, as I have already explained, is the
protoplasm which constitutes the bodies of all Protozoa, whether
Gregarinid, Infusoria, Rhizopod, Eadiolaria, or Sponge.

Now take your dead Sponge into your hand, and place it in water,
and if you watch it carefully you will see the water enter in at the
smaller pores till the Sponge is full. Now squeeze it, and you will
notice that the water runs out of the larger openings, and, that
when you have squeezed out all the water, the Sponge will suddenly
dilate to its full size, showing that it possesses the power of con-
tractility.

But the Sponge, when tenanted by its layer of sarcode, can do all
that you have done with your hands. It can contract its skeleton,
and force out the water from the large or efferent openings, just as
you did when you squeezed it, and it can then relax the texture,
allowing the fluid containing its food to enter in by the small or
afferent openings.

A now venerable grey-headed philosopher, who has for forty years
been silently working at University College (the well-known and
respected Dr. Grant), was the first person who saw the living Sponge
do what I have described ; and well indeed can I share the delight
which he must have felt when he first saw the magnificent sight.
A lump of jelly contracting its skeleton as perfectly as the muscular
finger of the highly-organised man ! And small fountains of water
pouring out of the large openings, containing, among effete and
digested matter, ova, or eggs, or germs of future Sponges ! Let us
have his own description. It has been often quoted, but not once
too often : —

" On moving the watch glass, so as to bring one of the apertures
on the side of the Sponge fully into view, I beheld, for the first
time, the splendid spectacle of this living fountain vomiting forth,
from a circular cavity, an impetuous torrent of liquid matter, and
hurling along in rapid succession opaque masses, which it strewed
everywhere around. The beauty and novelty of such a scene in the
animal kingdom long arrested my attention ; but, after twenty-five
minutes of constant observation, I was obliged to withdraw my eye

THE LOWER FORMS OF LIFE. 65

from fatigue, without having seen the torrent for one instant change
its direction, or dimmish in the slightest degree the rapidity of its
course."

I have said that in this efferent fountain the germs of the Sponge
were emitted. Let us take up one of these tiny creatures and
follow out its life history.

This germ, or gemmule, is essentially a Protozoon. It is a cell
formed of sarcode. If you look attentively through a lens you will
observe that the efferent fountain of water will propel this little
germ to a considerable distance, where you would, a priori, imagine
that it would be left to sink to the bottom. No such thing. You
will find that, beyond the influence of the fountain of water, it has
the power of motion, and, if you examine it attentively, you will
find that this is due to a series of delicate cilia attached to the
posterior part of the cell, just as we observed in the bell of
Vorticella. This Sponge germ is an independent atom of living
matter, and it moves through the water propelled by a will prescient
of its future destiny among living things.

At length this little germ finds a resting place, which, when once
found, is, like that of the Vorticella or the oyster, its locality for
life. This is either a shell, a stone, a rock, or some solid substance
in the water. When it touches such a substance it becomes attached
to it by its ciliated extremity, and then flattens itself out into a thin
disc, well shown in Fig. 81. Now it is seldom that very small

Fig. 81. — Three sponge gemmules fixed to a rock and spread out The spiculse are seen
being developed. There were three more on the rock from which Mr Bowerbank's plate
was taken, all of which would have united together, forming one Sponge.

sponges of the larger species are found, and this arises from the
fact that a number of other germs fix themselves to the same foun-
dation, and they then join together and grow up as one Sponge, as
the figures in the cut would have done had they not been taken out
of the water. Well, this delicate, thin, flattened-out film of sarcode
would be a most agreeable bonne louche for the numerous predatory
inhabitants of the sea, and more particularly would it be liable to
the insinuating attacks of small Annelids. But, to compensate for
this danger, the Sponge is endowed with the power of forming a
most remarkable series of flinty or chalky spiculse, which, among

F

66

POPULAR ILLUSTRATIONS OF

other things, it uses as weapons of defence. Now, the first thing
that the little Sponge does after it has become fixed to the rock, is to
begin to manufacture these spiculae, and it so arranges them that
any animal coming full tilt to make a mouthful stands a fair chance
of being impaled on their spear-like points. Should the assailant,
worm-like, try to work its way through the outer defences, it finds
a masked chevaux de frise all pointing outwards beneath the external
covering of the Sponge. This matter of self-defence being provided
for, that of growth comes next. Again the spiculse are brought into
play, to act as supports to the proper texture of the animal — that

Figs. 82 (magnified 260 diam.) and 83 (magnified 160 diam.), sponge-spiculse of the skeleton.

Fig. 84. — Connecting spiculum (magnified 90 diam.).

Fig. 85.— Defensive spiculum (magnified 308 diam.), from 2200 fathoms, Indian Ocean.

Fig. 86.— Tension spiculum (magnified 660 diam ).

Fig. 87.— Retentive spiculum (magnified 400 diam.).

which we know as Sponge, which scientific chemists call " keratode,"
but which Grant very properly altered to "keratose," because,
although Sponge may appear like horny elastic fibre, it is not chemi-
cally or structurally allied to horn ; while, strange as it may appear,
it differs but very little in chemical constitution from silk. Well,
then, the spongy texture grows upwards, all its internal network and
canals being lined with a reproduction of the sarcode cell which con-

THE LOWER FOEMS OF LIFE. 67

stituted the germ, while the small inferent openings, termed pores,
and the large efferent openings, termed osculae, being established,
the process of feeding, so essential to growth in all animals, goes on
prosperously. The food entering by the pores is thoroughly digested,
and those particles which are not nutritious are rejected through the
osculae. This food appears to consist of particles of either animal
or vegetable matter, or both. Bowerbank thinks that some of the
internal defensive spiculae are used for the purpose of destroying
any live creature which may be drawn among them. Other
spiculse are used as organs of prehension — that is, of attaching
the Sponge to the rock ; others are used as special organs of
defence to the sarcode and the ovarium containing the gemmules.
These spiculae are many of them very beautiful microscopic forms ;
in fact, Bowerbank figures and describes at least 240 different
varieties.

Such is a simple statement of the life history of a Sponge. As
it does not grow continuously, but is subject to periodical periods of
development, I cannot give any real data about the time occupied
in the growth of any of the large species in our shop windows. If,
however, two or more Sponges of the same species come into
contact, they will join housekeeping and become united into a
single Sponge. Different species, however, decline any such intimate
association.

It will have been noticed in my short description that, in some
respects, the Sponges possess a higher degree of organisation than
any of the animals before noticed. For instance, they can close the
osculse and open them at their will. By closing them they stop the
fountain, which when open flows from them, This shows the
possession of a power bordering on that of muscular fibre ; and this
is one of the reasons why Kolliker places them at the head of the
Protozoa.

To my mind there is something marvellously interesting in the
economy of the Sponge. How beautiful a provision is made for the
tiny speck which floats by its cilia through the world of waters in
search of the rock which is to be its home ; how wonderful its
system of spiculee, all of which it is able to form according to its
wants, now for defence, now for prehension, now for attack, and
always for support to the horny-like fibrous covering within which
it is to live ; how marvellous the reproduction of its germs — and all
this in an animal which, to the most searching eye of science, shows
no more organisation than a layer of glue or jelly ! But the will !
— the power to open and shut the oscula capriciously, and to expel
the water with great force therefrom, just as it has occasion to do
so ! All this is truly wonderful, and would be inexplicable did we

F2

68 POPULAR ILLUSTRATIONS OF

not know that the same Power which, as Newton remarked, caused
the apple to fall to the ground, is the author and director of all
laws, whether they affect the physical or the animal world.

The Sponges are found fossil in the oldest rocks. They attain
their maximum in the chalk. Most of our flints have a Sponge
or its spiculse as a nucleus, round which the silicious mattter has
accumulated.

With this chapter my history of the Protozoa finishes. In my
next I shall treat of beings a step higher in the scale of existence.

THE LOWER FORMS OF LIFE. 69

PART III.

THE CCELENTERATA.

CHAPTER I.
THE HYDROZOA.

CUVIER included the Protozoa and the group now to be considered
in the sub-kingdom Radiata, so called because the animals were
formed upon a type which consisted of a centre and parts radiating
therefrom. Agassiz, in his recent Graham lectures, has made the
most of this by endeavouring to show that the great animal king-
dom was specially created under four types, of which the radiate,
as formed by Ouvier, was the lowest. But then, to support his
view, he has been obliged to take his best specimens of the radiate
type from the Echinodermata, an order placed by all scientific
writers of the present day in a much higher position in the scale of
being. The two things cannot be reconciled. We must either
group together animals having a similar external arrangement of
organs, but with a totally .different internal anatomy, or we must
do that which has been done — viz., bring together great classes
which have a similarity of organisation, and place them in the scale
as they rise one above the other in the links of a great chain, each
larger than that which precedes it. It is a favourite argument that
such a chain does not exist in nature. This is, literally speaking,
true ; but the difficulty is at once got over by dividing the chain
into six parts, each link in each part being of greater value than its
predecessor, and the same with each chain when complete. Instead
of four we thus make six great types of organised life, one of plants
and five of animals. I have already considered two, and I now pro-
ceed to point out the salient parts of the third. I propose, however,
to sink altogether the term Eadiata, and to adopt for it that of Coelenr
terata — a plan pursued by the best modern comparative anatomists.
The name is at once suggestive to the scholar of that all-important
organ, the stomach (koilia, from koilos — hollow) ; and it owes its
origin to the fact that in the group of animals to which it belongs
a stomach is for the first time differentiated, as it is called in scien-
tific language.

70 POPULAR ILLUSTRATIONS OF

Hitherto we have found the food carried either into the general
cavity of the body, or into vacuoles interspersed through its sub-
stance. In the .Coelenterata, however, the body substance consists
of two layers — one an outside or integumentary organ, or skin,
called the ectoderm ; the other lining a cavity which is always pre-
sent, and which, communicating with the mouth by means of a
gullet, constitutes the stomach. This inner layer of body substance
is called the endoderm. Now these two layers consist of vesicular
bodies embodied in a matrix, the inner one having the cells applied
to each other more closely, and increasing from without inwards,
while in the outer layer they are more loosely scattered through the
body substance or matrix, and increase from within outwards. If
the reader will bear these simple facts in mind he will have a know-
ledge of the great difference which exists between this sub-kingdom
and the last. By these two layers most complicated organs are
developed. They produce deadly thread or poison cells, which have
the power of benumbing their prey ; they produce reproductive
organs, colouring or pigment bodies, and granular matters, which
are intimately connected with the great function of secretion ; they
can also protect themselves outwardly by organs of great beauty, or
develop a skeleton to support them, as in the great group of cal-
careous, curiously and elegantly built-up bodies known as Corals. It
is, in fact, upon the history in space and time of these structures
that I shall principally dwell in illustrating the Coelenterata. But
I will take a general view of the whole family, as its members
are rather celebrated for qualities which excite our interest and
curiosity.

The Coelenterata are divisible by anatomical differences as to the
connection of the two layers with each other into two classes — viz.,
(1) the Hydrozoa and (2) the Actinozoa.

1. THE HYDEOZOA.

The type of this class may be found in any stagnant ditch.
It is known by the name of Hydra, or fresh-water polyp. It
seldom exceeds, without its long tentacles, three-quarters of an
inch in length. Its body is gelatinous, but endowed with great
powers of contractility, and its stomach is capacious. From the
ectoderm, or outer skin, it has the power of projecting vast num-
bers of thread-like organs, with which it benumbs or kills its
prey. These are especially placed along the outer covering of the
long tentacles by which the prey is caught (Figs. 88-92), and
are projected by a beautiful mechanism presently to be described.
These tentacles spring from a margin immediately below the open-
ing which serves as a mouth (a, Fig. 88), and are spread out as

THE LOWER FORMS OP LIFE.

71

seen in the figure when the creature is hungry. Should any small
worm or animalcule come into contact with the tentacles as shown
in Fig. 92, it is immediately benumbed by the thread-like organs
before alluded to, which pierce the body of the victim. When seen
through the microscope the tentacles are found to be studded with
nodular protuberances, as shown in Fig. 94 (p. 72). If one of these
nodules is more closely examined it has the form shown in Fig. 95

Fig. 88. — The common Hydra viridis, or short-armed Hydra, with young budding from the

parent body.
Fig. 89. — The brown or long-armed Hydra (Hydra fusca), with young budding out from the

bodies of mother and daughters. The long tentacles spread out in the act of seeking for

prey (Carpenter).
Fig. 90. — Hydra floating through the water ; &, its sucker extremity, which, having become

dry, serves as a float.
Fig. 91.— The same digesting.

Fig. 92.— Hydra fusca, with a small worm and animalcule just caught in the tentacles.
Fig. 93.— Hydras •' progressing."

(p. 72) ; and if the thread-cell is treated with acetic acid it immediately
shoots out, with the action of a spring, a long sharp-pointed thread,
as seen in Fig. 96 (p. 72). By this means the prey is slain, and
it is then drawn up to the mouth by the tentacles, and gradually

72 POPULAR ILLUSTRATIONS OF

swallowed ; after which the creature takes its post-prandial nap,
assuming the form of Fig. 91 (p. 71).

The Hydra has no legs, but it can move from place to place not-
withstanding, for it is reasonable to expect that its hunting country
will require changing. In order to " progress" it assumes the form
shown in Fig. 93 (p. 71). But he is also one of the most cunning of
rascals, for, well knowing that he must have a bad name, he adopts
the following method of moving about, and, at the same time, of
coming unawares upon his victim. He allows the sucker end of his

$6 i

Fig. 94.— Tentacle of Hydra magnified 140 diameters.

Fig. 95.—" Thread cell," containing stinging organs, magnified 450 diameters.

Fig. 96.— The same, with the spines and filaments protruded, magnified 450 diameters.

body (b, Fig. 90, p. 71) to become dry, in which condition it acts as a
float, and thus he moves about the water with the currents, aided
by any rowing power which his tentacles may possess.

One of the modes by which this singular creature increases is
shown at Figs. 88 and 89 (p. 71), in which young ones are seen grow-
ing like the buds of a tree. In Fig. 89 a third generation is seen
springing from the bodies of the second, and throwing out their
feelers in search of food, just like their mother and grandmother,
to whom they still retain an " attachment." Their tentacles never
catch each other, but close instantly upon any unfortunate animal-
cule which ventures into such a dangerous country. Carpenter tells
us that-it is not unusual to see the parent and its young each get
hold of the opposite end of some small worm, and commence a
pulling fight for mastery. Strength, I presume, succeeds in the

THE LOWER FORMS OF LIFE. 73

end. After a time the youngster separates from its respected
parent and starts a hydra life of its own. They also increase
by fissiperation or division, as we have seen done by the Infusoria,
and also by the union of the sexes.

Trembley, by whom the true nature of the fresh-water Hydra was
first determined, performed, many most interesting experiments with
them, which have been fully verified by later inquirers. Among other
things, he tells us that upon one occasion two Hydrse had seized
upon the same worm, and, after a short struggle, the strongest being
unable to get the worm away, swallowed it with rts brother polyp at
the same time. But he was no nearer the winner of the battle by
this manoBuvre, for digestion having gone on equally in the stomachs
of the two Hydrae, the swallowed one was ejected, none the worse for
its adventure in the belly of the polyp. On another occasion he
turned a Hydra inside out by means of a fine wire ; thus the stomach
was outside. But this process did not at all inconvenience the
creature, which went on catching animalculse and digesting them
with what had been his outer skin, just as though nothing had
happened.

To vary his experiment he cut one into two parts, and was
surprised to find that in a short time each developed itself into a
perfect polyp. He then cut off a small piece with the same result,
and even divided one into fifty parts, with the effect of causing fifty
new Hydrse to rise up. He then grafted one upon another, and even
two of different species, and they grew firmly united, like the
Siamese twins. It is remarked that when a Hydra is cut into two
that the head portion develops a tail part more quickly than the tail
part will form a head and tentacles.

The history of the fresh-water polyp, or Hydra, is a very important
and interesting one in science. The celebrated Reaumer was a firm
believer in the floral or vegetative character of Corals, Madrepores,
&c. ; and when Peysonnel, a French naval surgeon, addressed a
memoir to the French Academy in 1727, maintaining their animal
nature, he was strongly opposed by Eeaumer. Peysonnel, being
quite sure that he was right, published, in 1751, a paper in the
" Philosophical Transactions " of our Royal Society, and Trembley's
discovery of the Hydra came most opportunely to the assistance of
truth. The French Academy appointed a commission of inquiry,
which confirmed all Peysonnel' s statements. Eeaumer was convinced,
retracted his former opinions, and wrote in favour of the new
doctrine. Strange to say, however, the scientific world was not
convinced. Dr. Parsons analysed and combated Peysonnel' s views
in a paper read before the Eoyal Society in May, 1752, and he
seems to have carried the majority with him. About this time.

74

POPULAR ILLUSTRATIONS OF

100

Fig. 97. — Hermia glandulosa; natural size.

Fig. 98.— Portion of the same magnified ; e, glandular-looking tentacles.

Fig. 99.— Tubularia indivisa, natural size; c, root; d, head; /, crenosarc enclosed in horny

polypidom. The cross lines shown in the stalks are not seen when the animal is dead.
Fig. 100.— Head of T. indivisa magnified, showing the tentacles round the mouth (g) ; those

round the neck (ft) ; and a row of germs (i) round the base of the head (after Johnston).

THE LOWEE FOEM8 OF LIFE. 75

however, the matter was taken up by a thoughtful member of the
Eoyal Society — a merchant in London — whose name, John Ellis, is
bound up with the establishment of a great scientific truth. Ellis
took up the study of Zoophytes for his amusement,, and examined
them minutely with the microscope. The result was the complete
corroboration of Peysonnel's views, and the overthrow of the belief
in the vegetable character of Zoophytes. His celebrated work —
entitled " An Essay towards a Natural History of the Corallines
and other Marine Productions of the like kind, commonly found on
the Coasts of Great Britain and Ireland" — was published in 1755,
and in 1768 the Eoyal Society awarded to him the Copley Medal, as
the highest reward they could offer for what they termed, "the
great accession which natural knowledge has received from your
most accurate and ingenious investigation." Linnaeus was at this
time in the height of his great reputation, and he entered at once
into the spirit of Ellis' s discovery. Curious, enough, however, he
confined his belief to those forms which built up their skeletons
with lime — such as Coral — while he still maintained that the
Zoophytes which lived in a horny polypidom, as it is termed, were
flowers. The whole discussion is most interesting, and will repay
perusal. Since that day the study of these forms has left little to be
discovered, and, as I shall show presently, the animals which consti-
tute the formerly called flowers of Zoophytes are nothing more nor
less than close relations to the Hydra, of which, as I have shown, the
type lives in fresh water.

The description and figure of this creature which I have given
will forcibly remind the reader of the many-armed monster, the
Pieuvre, which is described with such horrid and disgusting detail
by Victor Hugo, in his new work, "The Toilers of the Sea."
This creature, the octopus or poulp, is called by the ancients a
polypus ; and it was the miniature likeness of our little Hydra to the
octopus, which induced Eeaumer to give the name of polypi to the
family. The term Hydra is derived from that of the monster which
was said to exist in the form of a sea-serpent, the head of which,
as the fable runs, was reproduced as often as it was cut off ; and it
is a very curious coincidence that we should have discovered in
modern days a creature whose head or tail will be reproduced when
cut off, just as that in the fable was said to have been. It is also
a most interesting fact that the little polyp, just three-quarters of
an inch long, should be, to some extent, externally at least, a
counterpart of the octopus described by Victor Hugo as destroying
human beings by entwining their long spinous arms about them. It
is not, however, certain that the largest specimen of octopus has
actually killed a human being ; at least, I am not aware of such an

76 POPULAR ILLUSTRATIONS OP

instance, although there is no doubt that legs and arms have actually
been seized by these creatures.

We shall best study the Hydra by looking at what we may term
its morphology, or the different forms which it assumes in what are
called Zoophytes, or plant-like animals. The word zoophyte is now
limited to that class of animals of which the Hydra is the type,
termed Polypifera, the compound skeletons of which have a plant-
like form. The term coralline, often popularly applied to this
group, is restricted to a small class which the botanists lay claim to,
and which are at once distinguished from the Zoophytes by the
absence of all traces of cells on their surface — a fact which the sea-
side rambler, armed with a pocket lens, will verify for himself at
any time.

Suppose, then, the said rambler finds, between tide marks attached
to a sea- weed, a form like the small central figure (97, p. 74), he will
at once by the above test know that he has a Zoophyte ; and if he
place it in a small glass of sea-water, and watch it with a lens, he
will observe at the end of each tube a fleshy-looking body, which
gradually protrudes its tentacles. This is -one of the Oorynidse, or
club-shaped Zoophytes. It is the simplest form which the hydra-
form animal assumes among the covered species. The tentacles, it
will be observed, spring from all parts of the polyp's body, and
although they can be drawn in and extended at pleasure, the body
cannot be withdrawn into the tube. The tentacles are very short,
and some of them being at a considerable distance from the creature's
mouth, the latter bends its purposely provided mobile neck and
meets the food which these distal tentacles may get hold of half way.

That part of the tube which is attached to the stone or sea-weed
is termed the root, and in this genus is closed. The branching
tubes, however, are all hollow, and are filled with a continuation of
the same substance as that which constitutes the body of the polyp
(Figs. 98, 99, p. 74), thus forming a compound animal, it may be, of
a hundred or a thousand brilliantly-coloured scarlet, or red, or rose
polyps, all connected with each other, and yet to a certain extent
independent organisms.

The reader will be somewhat reminded of the Ehizopoda before
described and figured ; but he will remember tnat when the
Lieberkuhnia, or Gromia, caught any prey in their pseudopodia it
was digested there and then, and the nutriment was conveyed into
the general, though imperfect and irregular, circulation. In the
Hydra and its congeners, however, the prey is brought by the ten-
tacles to the mouth, and is swallowed and digested in a regularly
formed stomach. Hence the great biological difference between the
two forms. The animal inhabiting the Corynid as well as the other

THE LOWER FORMS OF LIFE. 77

Zoophytes is in every respect similar to the Hydra ; in fact, were
we to imagine the young buds sprouting and re-sprouting from each
other, as shown in Fig. 89 (p. 71), not to be cast off and become
independent individuals, but to be covered with a horny or calcareous
case, it would represent one of the tree-like branching Zoophytes.

We are now prepared to see the real simplicity of the principles
upon which animals are classified, and I must warn those who wish
to gain any knowledge of zoology not to neglect this most important
part of the subject because it may appear dry ; on the contrary, it
is the very pith and marrow of the whole subject.

The Coelenterata, as I have said, are divided into two classes —
the Hydrozoa, which we are now considering, which have stomachs
hollowed out, as it were, in the substance of the animal ; and
Actinozoa, in which the stomach is more or less separated or free.
The Hydrse, which have formed the subject of this chapter, in their
naked form, constitute the first family, into which Hydrozoa are
divided, and are termed Hydridae, which is represented by a single
genus Hydra, and four or five species. Well, the whole family of
the Hydridae, being very much alike, I have not thought it necessary
to draw attention to its divisions. The second family, the Corynidae,
are those I am now treating of, and the genera differ from each
other in several particulars ; but all agree in the fact that the
polyp cannot withdraw its club-shaped body within the tube which
supports it. The specimen figured belongs to a genus erected by
Johnston, called Hermia, and the name was taken from the lines in
Shakespeare —

What wicked and dissembling glass of mine
Made me compare with Hermia's sphery eyne.

The glandular-looking bodies at the end of the tentacles (Fig. 98,
p. 74) are as the guardians of the creature, the supposed " sphery
e'yne " which induced Johnston to characterise his new genus under
the name Heraiia — a fanciful name enough ; but then it must be
remembered that all classification is more or less artificial.

There are several genera of Corynidae. The most extensive is that
of Tubulari, and perhaps the best known example is that of Tubu-
laria indivisa, so called because each tube remains single, and does
not branch off like many of the others. The animal which protrudes
from the extremity of the tube is of a beautiful scarlet colour, and
the head (Fig. 100, p. 74) is crested with two rows of tentacula.
Several of these tubes rise from the same part of the stone, or shell,
upon which the root is fixed, as shown in the figure (99, c, p. 74).
Ellis compared the tubes to straws without joints. They are filled
with a reddish pink soft substance, which is connected with the head.

78 POPULAR ILLUSTRATIONS OF

The neck is very narrow ; and when the animal becomes weak in
the aquarium the head readily drops off. In scientific language
the head (Fig. 99, d, p. 74) is called a polypite, while that in the
tubes is denominated a coenosarc (koinos, common — sarx, flesh)
(Fig. 99, /, p. 74) ; the two together are called hydrosoma (hydra
and soma, body), and the point of attachment or root hydrorhiza
(hydra and rhiza, root), while the polyp cells which are absent in
Corynidae — viz., the small cups in which the polypite lives, are
called hydrothecce (hydra and theca, covering).

These names are all expressive and simple enough. Then the
horny or calcareous skeleton was called by Kirby a polypary ;
others, Johnston among them, have used the term polypidom to
express the same thing ; and the cavity which exists in the body
of the polyp, and which extends through the coanosarc, is called
the somatic cavity. A little attention to the terminology and the
student will be able to pursue his sea-side investigations very easily.

. CHAPTEE II.
THE HYDROZOA (continued).

The Sertularidce (sertulum, a garland of flowers ; terminal, ides)
form the third group into which the Hydrozoa are divided. They
are at once distinguished from the Corynidae by the bell-like expan-
sions— called, it will be remembered, hydrothecae — which crowd all
the branches of the Zoophyte. Into these bells the expanded head
of the polyp can retract, thus distinguishing them from the Cory-
nidae, which have not that power. The family is divided into many
different genera, and forms by far the most numerous of any of the
divisions of Hydrozoa. Fig. 101 represents one of the common
species, and may be taken to illustrate the typical parts of the
Zoophyte. To show this clearly, I have at Fig. 102 given a repre-
sentation of the upper part magnified. The head of the polyp,
with all its tentacles spread out in search of food, is seen at a, and
at b it is shown contracted and withdrawn into the hydrotheca (c).
Then observe the coenosarc (d) passing along from the head (a),
covered with a bead-like tube, which, it will be remembered, is part
of what is called the polypidom.

Observe how this coenosarc joins with the other branches, and
at e constitutes the centre of the stem of the Zoophyte, just like
the pith of a tree.

THE LOWER FORMS OF LIFE.

79

If you will look at Fig. 101 you will observe that lower down
such a stem is attached to a piece of rock. Then remember that
this ccenosarc in its totality, and the stomach and heads in the
hydrothecse, termed polypites in their totality, constitute the com-

-102

Fig. 101.— Laomedea gelatinosa, natural size ; polyps reddish.

Fig. 102.— Part of the same magnified ; o, polyps with tentacles expanded in search of food;
6, the same retracted into c, the hydrotheca ; d d d, the coenosarc.

pound animal called, with its external covering, a Zoophyte. And
further, let me repeat, that this compound animal is formed of an
outer skin, called an ectoderm, and an inner skin, called an endoderm,
and that the centre is hollow throughout, constituting what is

80 POPULAR ILLUSTRATIONS OF

termed the somatic cavity : and you will understand ever more all
about the formation and terminology of Zoophytes, the Sertularidae
being typical of the family. I have said nothing about the bell
(/, Fig. 102, p. 79) containing the rounded-looking bodies, because
these are connected with the creature's propagation, and the whole
interesting subject of development will be best considered after the
different families have been illustrated and described.

Well, now, as I have said before, these Sertularidse are very
beautiful objects, and, as most people go to the sea-side, I
hope I shall be the means of adding to their pleasure by point-
ing out how they can be recognised and studied. They are
found upon anything which will give them a firm attachment —
shells, pebbles, rocks, pieces of wood — and are even parasitical
on sea-weed ; and the heads and tentacles are of various colours,
looking, as their name implies, like garlands or bouquets of
flowers. Every one at the sea-side who cares about studying natural
objects should carry with him a good pocket or Stanhope lens, which
he can buy from an optician for a few shillings, and if he places
his Zoophyte in a shallow vessel, and covers it entirely with sea-
water, he will be able to watch its movements and examine its
beautiful structure with the greatest ease. I have appended some
magnified figures of each known genus of the British Sertularidse,
and upon these I will offer a few general remarks.

As seen by the naked eye the Sertularidse have little to invite
attention, many of them being passed over as minute sea-weeds, or
lumps of moss, or something not at all worth looking at by those
who are attracted by the more gorgeous visible beauties of the sea-
anemone, or the Coral, or

Pale glistering pearls and rainbow-coloured shells.

Still there are many of them which have a characteristic form, which
attracts the eye of the collector at once. Thus, Fig. 103 is exactly
like a miniature tree, with the branches springing from the bottom
of the main trunk, and occurring in the same order and regularity
as in the tree.

Observe also that the same rule of alternation obtains in the
branches as is observed in the plant. The thick-looking stem from
which the branchlets proceed in the figure is one of these branches
magnified. The main stem in a state of nature is in fine specimens
more than half the thickness of that in the figure. It is only when
magnified that the minute terminal branches show the cells and
polyps as seen in the figure. The latter are yellowish in colour.
The branches all come off at an acute angle from the stem, which
gives them the appearance of the backbone of a fish, and hence it is

THE LOWER FORMS OF LIFE.

81

Fig. 103.— Thoahalecina (magnified) ; common on shells and stones in deep water; herring-
bone coralline ; polyps yellow.

Fig. 104. — Sertularia polyzonias (magnified) ; on shells and other Zoophytes in deep water
polyps white, sometimes bright yellow.

Fig. 105.— Thuiaria thuia (young), magnified; on shells in deep water.

Fig. 106. — The same (mature) ; called by the fishermen of Scarborough the "Bottle-brush
Coralline ;" polyps white.

called the " Herring-bone Coralline." It is found on shells and
rocks, below the low-water tide mark. There are two other species

G

82

POPULAR ILLUSTRATIONS OF

at least in which the hydrothecse may be more easily distinguished
by the naked eye. In one of these, T. muricata, the cells are
covered with spinous ridges. The other is a rare species, called after
Mr. Bean, of Scarborough, its discoverer.

Figure 104 (p. 81) is an example of the larger genus, Sertularia.
It was called the "Great Tooth Coralline" by Ellis, and looks, in its

Fig. 107.—Antenmilaria antennina (magnified); common on shells and rocks in deep water;
polyps yellowish white.

Fig. K)8.—Plumulariapinnata (magnified); on shells and stones in deep water; polyps
reddish.

Fig. IW.—Campanularia verticillata (magnified); on shells: " Horsetail Coralline."

natural condition, when attached to a fucus or shell, like long threads
of small " glistering pearls." One of the species, S. argentea, when
mature is a very striking object. The stem is regularly divided,
like that of a plant, by nodes, from each of which springs a whorl
of branches in which the polyp cells are fixed. It attains the length

THE LOWER FORMS OF LIFE. 83

of eighteen or even thirty-six inches, in which state it looks like the
tail of a squirrel, and has hence obtained the name of " Squirrel-
tailed Coralline." Johnston, in his '" British Zoophytes," describes
sixty-eight species and varieties of the Sertularia, and figures fifteen
or sixteen of them. Figures 105 and 106' (p. 81) are the young
and mature species, which I have selected to illustrate the genus
Thuiaria, so called from the Greek word for cedar, Thuia, and the
terminal aria. In its mature state the branches fall off the lower
part of the stem, giving it the appearance of a " Bottle Brush,"
which is its popular name among the fishermen of Scarborough. It
reaches to a height of twelve inches. The hydrothecae or polyp
cells are seen at a, arranged alternately on each side of the magni-
fied branchlet. There are only two species of Thuiaria.

Figure 107 illustrates the genus Antennularia, of which there is
one species. In their natural state they are seen springing from a
clustered root, and rising up single or irregularly branched to a
height of ten or twelve inches. When dried the unbranched speci-
mens look like the antennae of a lobster ; hence the scientific (Anten-
nularia) and popular names (" Lobster's Horn," or "Sea-Bend")
given to it by Ellis. The colour is yellowish horn.

Figure 108 illustrates a very beautiful genus — that of Plumularia,
so called from their graceful feathered forms — of which Johnston
figures eight species. The one figured is called by Ellis the " Sea-
Bristle," and springs from some shale or stone like a bristle fastened
on the upper half, with branches carrying the hydrothecae, as shown
in the figures. It is thus described by the Rev. D. Landsborough,
in his "Excursions to the Isle of Arran : "

" There was something in the scollop shell more conspicuous ; . .
it was like a drookit white feather. But place it again in the water,
and what does it become ? It has recovered from its state of
collapse, and though still like a feather it is one of great beauty and
elegance ; it is a Zoophyte, Plumularia pinnata. You would not
think that that beautiful white feather had life ; but you see only
the habitations. The alarmed inhabitants have fled into their
houses (hydrothecae — C. B. B.) But place the polypidom, as it is
called, in a tumbler of sea-water, and when the alarm is over the
inhabitants will again appear. The polyps are hydraform, and
spread forth many tentacula in search of food, which they greedily
grasp. The feather is formed of calcareous matter, mixed with
gelatine to give it flexibility, so that it may better stand the buffeting
of the waves. Observe the stem or quill of the feather, and you
will see that it is full of red matter (the coenosarc — 0. E. B.)
Every plumule of the feather is a street. Even with the naked eye
you may observe in each plumule about a dozen notches. Each of

G 2

84

POPULAE ILLUSTEATIONS OF

Fig. MO.

-; — z

these is the house or cell of a
polyp ; so that in a good specimen
we see a kind of marine village,
which, under the teaching of God,
-y' ] has been beautifully constructed
by the thousand inhabitants it
contains."

The last genus in the British
forms of the order Sertularidse is
illustrated in Fig. 109 (p. 82).
They are called Campanularia
because the Hydrothecae are bell-
shaped. Johnston figures three
real, and figures one and describes
two doubtful species — six in all —
as inhabiting our coasts. The species
figured looks in a natural state like
a small plant rising from a single
stem, and branching off into the
shape of a "horse's tail," which

fc is the popular name given to it by

Ellis.

THE CALTCOPHOEiD-as.
The next phase in the morpho-
logy of the Hydrozoa is observed in

~~3'~ a most interesting family of Zoo-

phytes, found only far out at sea,
and therefore termed oceanic. It
will not be necessary for me to dwell
long upon this or the next group,
also oceanic — viz., Physophoridse,
inasmuch as specimens are not so
accessible for examination to our
sea-side ramblers. But they are
very interesting and beautiful
creatures notwithstanding. The

Fig. 110.— Diphyes dispor (magnified) ; a, the
coenosarc ; 6, the polyp with its single ten-
tacle ; e, the same, covered with its hydro-
phyllum ; c, nectosac, or locomotive organ ;
d, the somatocyst; /, duct leading from the
hydraecium, which, joining with others,
forms the connection of the swimming floats
and the somatic cavity; g>, the proximal
nectocalyx, or "swimming float;" gr2, the
distal nectocalyx; i, t, the mouth of the
nectosac ; k, the hydraecium ; *i, the hydrsa-
eial canal (after Huxley).

THE LOWER FORMS OF LIFE. 85

Calycophoridee (cup-bearing Zoophytes), so called by reason of the
" swimming -cup," or nectocalyx, to which the different parts of the
animal are attached (Fig. 110, gl and <72), are very singular-looking
creatures, as may be seen by looking at Fig. 110, which represents
the first member of the family ever discovered. They occur in
various parts of the world, but especially in tropical seas. They are,
however, abundant in the Mediterranean, and are sometimes found
floating in the waters of our own coasts. I will endeavour to give
the reader, by the assistance of the figure, a description of these
Zoophytes, and here I shall call into requisition a knowledge of the
terms given to the different parts of the compound animal.

Everybody is acquainted with the bright glistening " jelly fish"
left on our shores by the receding tide, and many have reason to
remember them on account of their stinging qualities. Now I have
only mentioned these "jellv fish" in connection with our cup-
bearing zoophytes in order that we may have an idea of their bodily
consistence and character. They have no other connection with
them except the ties of family, which we shall see by and by. I
may here state, however, in parenthesis, that they who desire to get
a sound knowledge of zoology must ignore such terms as "jelly
fish" or "shell fish." These animals are not fish in any sense
of the word. I should not have thought it necessary to make this
apparently trivial remark had I not found that even educated men
will sometimes keep up a delusive nomenclature because it is popular.

Well, then, the Calycophoridse are animals possessing a body
having the consistence and appearance of the Medusae found on our
sea-shores, but, as a general rule, the shape and appearance shown
in Fig. 110. They consist in this family, the Dyphydse, of two
similarly formed " swimming cups," or nectocalyces, as they are
called by Professor Huxley, g1 and g2 fitting into each other.

In the centre of these swimming cups are noticed the two long
open tubular-looking bodies termed nectosacs (c). These are the
organs of locomotion, and are formed of longitudinally-placed
muscular fibres, by the contraction of which the water is expelled
from the opening (i) in force, and, as a necessary consequence, the
animal is propelled backwards in the direction of the arrow. At d
will be noticed a chamber filled with inclosed spaces termed vacuoles,
which give it a cellular appearance.

This is the proximal extremity of the coenosarc (a), which is not,
as I before mentioned, covered with a horny case like the Sertularidae.
This chamber is called by Huxley the somatocyst, and it will be
observed that it is connected by a narrow neck with another dilated
portion of the coenosarc, which is, in fact, a chamber from which
proceed the various ducts (/) which connect the organs of locomotion

86 POPULAR ILLUSTRATIONS OF

with the somatic cavity. The ccenosarc now proceeds between the
two swimming bells, and through the distal one, whence it floats
freely in the water. It bears naked polypites (b), each having a
single tentacle, and also polypites covered with a leafylike organ,
termed hydrophyllum by Huxley (e).

Such is the beautiful provision by which the unattached or free
Zoophyte is enabled to float or swim through the water. The
natural size of the specimen figured is shown by the line by the side
of the figure. Nothing can exceed the delicate beauty of these
creatures when seen first in their native seas. The coenosarc (a),
with its naked and covered series of polypites (b and e), sometimes
reaches a length of several inches, and has fifty or sixty or more of
these bodies attached to it. They can be drawn entirely within the
chamber (&), which is therefore called the house of the Hydra, or, in
scientific language, the hydrsecium. So delicate is this ccenosarc that
sometimes we are told it can only be seen by the play of the light,
and the slightest touch will make it separate from the floats. Cuvier
thought these floats were two distinct individual animals, and hence
he gave them the name of Diphyes. Professor Huxley has divided
the order Calycophoridae into four families. The first three are
separated from each other by differences in the hydraecia and hydro-
phylla, which I need not enter into. The fourth has many swimming
bladders instead of two, and the hydrsecium (k, Fig. 1.10, p. 84) is
incomplete. Professor Huxley's history of the " Oceanic Hydrozoa,"
published by the Bay Society, is a model of scientific detail and
elaborate and accurate illustration. Although we cannot go through
the voyage of the Eattlesnake with the learned Professor, we can
imagine the patient investigation and the real love of science with
which, during that survey, he dealt with the various new links in
the great chain which came under his notice. And we cannot be
too grateful to the man by whose labours the means of studying the
beautiful inhabitants of the wide sea are brought within the reach
of our library table.

CHAPTER III.
THE PHYSOPHORIIXE.

THE Physophoridse are, as their name expresses, "Bladder-bearing
Zoophytes." The order is represented, but not typically, by the
well-known singular creature called by sailors " the Portuguese man-
of-war" — the Physalia pelagica of scientific naturalists. An oblong
bladder-like body about the size of a goose's egg, or larger, with a

THE LOWER FORMS OF LIFE. 87

ridge-like back terminating in a point, which is movable at the
will of the creature, with a fringe round the part in contact with
the water, and a number of long blue tentacula, extending some-
times ten or twelve feet into the water ; the beak end of the back a
rich carmine, and the rest blue, while the sides and fringe are
iridescent with yellow and green and blue, glittering in the warm
tropical sun, and gilding this fairy of the sea with the rich colour-
ing and harmonised tints which mark a thing of beauty. Such is
the "Portuguese man-of-war," or "galley," or "frigate," which
sometimes in countless thousands floats along at the mercy of the
currents or the winds of the warm seas of the tropics.

Monsignor Virtue, E.G., Chaplain to the Forces, and now stationed
in Colchester, informs me that this Zoophyte is very common on
the shores of the islands of Bermuda, where, like the Medusae
on our own coast, it is thrown helpless by the receding tide.
He says that he never saw there any of the yellow or green tints
which are described and figured in the second volume of the Intel-
lectual Observer, p. 233, by Mr. Noel Humphreys, from a British
specimen ; that the principal colourings are the amaranth crest, and
the deep blue of the rest of the ridge and sides relieved by white.
He also says that he never saw any specimen there having the
number of tentacles figured by Mr. Humphreys, and that the full-
grown size is considerably larger than a goose's egg, as stated by
me on the authority of Dutertre in his description of the Antilles.

Mr. Bennett, in his " Gatherings of a Naturalist in Australia,"
where he gives a most interesting account of the Physaliae, states
the size of a full-grown specimen to be 5in. long, and the tentacula
from 4ft. to 5ft., with the power of much greater extension. Mr.
Humphreys does not give the dimensions of the specimens figured
in the Intellectual Observer, nor does he say whether the figure, which
is 37-10thin. by 1-Jin., is the natural size or not — an omission much
to be regretted. The discrepancy, however, in size and colour in the
description of this Zoophyte arises not only from the fact that they
differ in both according to age, but that in the opinion of some
naturalists they are divisible into several species. M. Eschscholtz
describes three species of Physalia :

1. P. Oaravella, which is 8in. by 2 Jin. of bright purplish red
colour, with dark extremities and blue lines in the fold of the crest,
Tentacles red, with dark purple acetubula ; the smaller ones blue.
Hab., Atlantic, from Azores to Brazil.

2. P. Pelagica. — 2 Jin. long; when young, pale blue. In the
adult both ends are green, and the crest purple in its highest part ;
tentacles blue, with dark acetubula. Hab,, Atlantic, especially near
Cape of Good Hope.

88 POPULAR ILLUSTRATIONS OF

3. P. Utriculus. — Length, 3 Jin. ; colour of the crest and middle
part of the bladder, greenish; the two extremities blue. Hab.,
tropical region of Pacific.

Professor Huxley, who follows Eschscholtz in this division,
expresses doubts whether these species are distinct or not ; and he
feelingly exclaims that the study of the species-making efforts of
Von Olfers, Lesson, and Lamarck had only one result — that of pro-
ducing a somewhat unpleasant vertigo. Mr. Bennett has given us
the best account of the Physalis, for he had opportunities of
examining any number of them on the Australian coasts, whereon
they were cast after storms. I will give a brief resume of his
description.

The bladder (a, Fig. Ill, p. 90) is about five inches long in adult
specimens, and the dependent tentacula (b) are several feet in length,
but capable of being extended much farther to seize any victim
which may be within reach thereof. The bladder is tough, slightly
elastic, and semi-transparent. Its lower part is of a light blue
colour, streaked or veined almost imperceptibly with delicate green
pencillings, the crest and beak being of a rich carmine, changing in
different lights to a brown, green, or purple. These colours soon
fade when out of the water, except the tentacles, which retain their
rich purple colour for a considerable time. Mr. Bennett says the
creature has no power of guiding its bladder-like float, but is at the
mercy of wind and tide, and that it cannot collapse or distend its
bladder by the exclusion or admission of air. The long tentacles
appear like a connected series of globules containing fluid, having a
sucker at the free end, which they can fix tightly on their prey,
benumbing it at the same time. This is not, however, done by the
exudation of a glutinous substance, as described by Mr. Bennett, but
by the agency of a vast number of thread cells, from l-50th to
1-3 00th of an inch in diameter, which send out threads, as already
described by the Hydra (Figs. 115 and 116, p. 91). The Physalis has
the power with these threads of inflicting great pain on the human
hand, round which they will entwine themselves if carelessly taken
hold of, as M. Dute"rtre tells us he did in one instance to his cost,
the pain produced causing him to call out most lustily. Mr. Bennett
also, with true scientific zeal, purposely exposed himself to one of
their unfriendly squeezes. He seized hold of the bladder, and
immediately the creature lifted up its tentacles and wound them
round his hand and fingers, giving him no little pain and some
difficulty in getting rid of their embraces. He says the violent
stinging continued so long as the smallest particle of tentacle
remained attached to his hand. There were also constitutional dis-
turbances afterwards, such as quick pulse, fever, impeded action of

THE LOWER FORMS OF LIFE. 89

the muscles of the chest, which were stiff, as in rheumatism, causing
painful dyspnoea.

In the specimen of Physalis caught off the Isle of Wight there
was a fish entangled in the tentacula ; and Mr. Bennett had the
opportunity of watching in his, taken under similar circumstances,
the progress of absorption of the digesting fish. As it shows all
the principal parts very well, I have figured the small variety called
by Eschscholtz P. utriculus, and which is drawn from life, and very
minutely described by Professor Huxley in his monograph of the
''Oceanic Hydrozoa." When the long tentacles (b) have come in
contact and seized and benumbed — say a small fish — they shorten
themselves by assuming a corkscrew form, and the prey is then
brought up to the polypites, which are seen with their open mouths
at c, and which are erroneously called small tentacles by those
who do not correctly follow the morphology of the Hydrozoa. The
prey being brought within convenient distance, each polypite applies
his sucker-like mouth, and the feast begins. Mr. Bennett describes
the passage of particles of the fish, as seen through the transparent
tissues along the absorbents. In reality he saw them passing into
the stomach of the polypites, just as he might witness the same
process in the fresh- water Hydra.

Like the Calycophoridse, many of the Physophoridae have swim-
ming cups ; but, in addition, they possess a remarkable organ called
a pneumatophore, which is, in fact, a chamber filled with air, by
which they float permanently in the water. Mark here the design
shown in the formation of the last two orders of Zoophytes. The
cup-bearers move voluntarily through the water, and are provided
with an apparatus for that purpose. The air-bag would be to them
an incumbrance ; but, as the bladder-bearers have no such organs
of locomotion, they are provided with an apparatus which, being
filled with a fluid lighter than water, keeps them permanently afloat.
Now, this pneumatophore is generally placed at the proximal end or
apex of the Physophorid ; and, as it cannot always be seen in draw-
ings of the animals, I have given a diagram from Professor Green's
excellent manual of the Coslenterata, which will illustrate the position
of this organ in all the genera, and at the same time show how the
order wt are now dealing with differs from the last (Fig. 117, p. 91).
This pneumatophore is diagnostic of the Physophoridae. In the
" Man-of-war " it constitutes the greater part of the larger bladder-
like coenosarc (a, Fig. Ill, p. 90). It contains within it another bag,
called by Huxley a pneumatocyst, which has an opening communi-
cating with the external air. There are two series of tentacles, the
long dependent (b), and the shorter ones (d). At the base of each
tentacle there is a fleshy ccecal bag (e), which is covered externally,

90

POPULAR ILLUSTRATIONS OF

113

Fig. 111. — Physalia utriculus,
" Portuguese man-of-war '
(natural size), original by
Professor Huxley — a, the
bladder, or fusiform cceno-
sarc, containing the pneu-
matophore and its cyst,
which occupy all the central
unshaded parts; a, the crest,
which can be depressed or
raised at the will of the
animal— 6, the long tentacles
(reduced one inch in the
figure)— d, the short ones— c,
the polypites— e, the tenta-
cular sac -/, velvety masses,
which consist of small poly-
pites and their tentacles.

Fig. 112.- A portion of the long tentacle
magnified— gr, a longitudinal muscular
band, which occupies its posterior
wall, and by means of which it
assumes the " corkscrew " form,
and is able to draw up m prey : h,
kidney-shaped bodies, which are seen
in Fig. Ill, 6 as mere dots. These
bodies contain an immense number
of "thread cells," as shown by the
round marks.

Fig. 113.-A polypite magnified — i,.
" thread cells," which are seen stud-
ding the margin of the mouth and
neck—*, villi on the endoderm of
stomach, which is shown to contain
particles of food (after Huxley).

THE LOWER FORMS OF LIFE.

91

like the tentacles and polypites, with thread cells, which the animal
can at will discharge, paralysing its victim or enemy. The
'•Portuguese man-of-war," therefore, consists of a large bladder-

a

Fig. 114.— A tentacle of P. ntriculus (a), as it is attached to its basal sac, 6.

Fig. 115.— One of the " thread cells " magnified.

Fig. 116.— The same after it has discharged its thread.

Fig. 117. Diagram of Physophorid ; a, the pneumatophore ; b, the necto-calices ; c, the poly-

pite and its tentacle ; d, the ccenosarc.

like coenosarc containing a pneumatophore and its pneumatocyst.
From the coenosarc depend the polypites (c), the tentacles (b and d),

92 POPULAE ILLUSTRATIONS OF

and the coecal appendages (e). It has the power of contracting and
dilating its crest, and can turn over or perform somersaults on the
surface of the sea, but when adult it has not, as far as is known, the
power of guiding itself or sinking to the bottom.

In 1862, Mr. Tudor, writing to the Times, stated that a consider-
able number of " Portuguese men-of-war " had been that summer
washed on to the shores of the Dorsetshire coast, and he remarked
that, as an old sailor, he never remembered seeing them before north
of 48° lat., and then only in the Gulf Stream. Mr. Tudor thought
that the appearance of these tropical creatures on our shores
indicated some extraordinary change in the course of the Gulf Stream.

For more minute points connected with the economy of the
Physalia — and there are many very interesting — I must refer the
reader to the complete and clear description and illustrations of
Professor Huxley, in his " Oceanic Hydrozoa," published by the Bay
Society.

The Physophoridae are divided into seven different families, most
of them consisting, as far as is at present known, of single genera.
They are all most interesting subjects of study to the naturalist,
but do not come within the scope of this work.

The next order of the Hydrozoa comprises a large and most
interesting class of animals — viz., the Medusidae, or so-called " jelly
fish " of our sea-shores.

CHAPTER IV.
THE

THERE is something very elegant and graceful in the glistening
Medusa as it rolls through the clearer waters of the sea in a
hot still day in July. The marvellous transparency of the creature,
as it bobs up and down by the side of the boat, renders it all
but invisible to the eye of the observer. But, fixing his attention
upon some coloured radiating markings, he will gradually realise the
fact that he is looking upon a semi-globular living thing, with a
central body and several tentaculee dependent from its rim. If,
again, the observer goes on to the shore at night, or sails along the
warm coasts of Italy, he may see hundreds of thousands of bright
sparks of light, or it may be balls of fire as large as small oranges,
moving through the water. In the day observation the weather
must be still and calm ; for his nocturnal visit, the sea should be

THE LOWER FORMS OF LIFE.

93

more or less rough, for phosphorescence, upon which the light depends,
is only produced when the creature is irritated.

The Medusa — or "jelly fish," or "sea blubber," as it is sometimes
called — consists of a more or less hemispherical or globular mass of
sparkling crystal-like jelly, arranged in the form of an umbrella ;
and hence this part of its body is, in scientific language, called the
"umbrella." Underneath, however, the analogy to the umbrella is
somewhat lost, for, to make the resemblance complete, we should
carry the dilating wires of the umbrella to the edge, and cover them
in beneath with another piece of silk — we should then form what is
in scientific language called the "sub-umbrella." Were the stick of

Fig. 118. - Pelagia cyanea—a, tentacles ; 6, arms ; c, umbrella.

the umbrella cut off a few inches below where it would enter the
centre of this sub-umbrella, it would represent the dependent polypite
of the Medusa, which again is either single or divided into what are
called arms, as shown in Fig. 118 and Fig. 119 (p. 94).

But the reader must imagine further, that, where the polypite
depends from the sub-umbrella, there is in the Medusa a cavity in
the gelatinous substance, and that this cavity communicates, on the
one hand, with the polypite, and on the other, by means of four, six,
eight, ten, or more canals, called "radiating canals," with the rim
of the umbrella (Fig. 122, b, p. 96). Bound the rim of the umbrella is

94

POPULAR ILLUSTRATIONS OF

another canal, called the "marginal canal" (Fig. 122, e, p. 96),
from which for the most part depend a series of tentaculae or
organs of prehension (Fig. 120, h, and Fig. 118, a, p. 93). Besides
these tentacles, and placed at their base, are a series of brilliantly-
coloured spots called ocelli, and which, though not eyes, are con-
sidered to be sight-giving organs ; also a series of vesicles or bulbs
which, though not ears, are considered to be sound-giving organs ;
and these two becoming united together, have received the name of
" lithocysts " (Fig. 121, d), for sometimes a bright crystal of silex
is found in their centre. In addition to this, there is in the majority
of species according to some systematists, and in all of the true

Fig. 119.— Rhizostoma Cuvieri— a, the "umbrella," with b, its scalloped edge; c, the eight
thick foliaceous arms, which, when the animal is in the water, are spread out and seize
the food.

Medusse according to others, a velum or veil, which is suspended
from the rim, as shown in Fig. 120, e, and Fig. 122, d (p. 96).
Now, between the radiating canals and the apex of the semi-globular
nectocalyx, or swimming bell, as the umbrella may be called, there
is more or less of the gelatinous, sparkling-looking substance of
which the creature is composed. This is membranous and cellular
in its character, and contains a clear fluid. It is non-contractile and

THE LOWER FORMS OF LIFE.

95

elastic, but not extensile. But this nectocalyx is distinguished at
once from that of the Calycophoridee, by the absence of the loco-
motive organ termed the nectocyst. A higher means of locomotion
is, however, provided for the Medusae. A fringe round the mouth
of the polypite and the margin of the umbrella, as well as the
substance of the tentacles, are formed of granular substances, and of

Fig. 120. — Medusa, in profile (the central and opposite parts are easily seen through the
bright sparkling substance of the animal) — a, the umbrella ; b, the sub-umbrella ; c, poly-
pite; d, radiating canals; e, velum (shown by dotted lines); /, marginal canal; </,
lithocysts ; h, marginal tentacula ; i, reproductive body ; k, manubrium.

Fig. 121.— a, portion of radiating canals (magnified still more) ; 6, radiating canal ; c, mar-
ginal canal ; d, ocelli or lithocysts ; e, tentacles.

this structure there radiates from the rim and along the sub-
umbrella a series of muscular bands, and it is by the contraction of
these that the creature moves. Such is the simple structure of these
beautiful creatures ; and yet, though simple, mark how we are rising
in the scale of being 1

96 POPULAR ILLUSTRATIONS OF

We have now membranes forming cells, and canals carrying
nutritious fluid ; we have at all events something like an eye and
an ear ; and we have undoubtedly motion produced by muscular
fibre — not as in the Calycophoridae, by working a pneumatic
apparatus, but by direct contraction. It is true we have hitherto no
evidence of a nervous system, but there is yet something to learn
in the economy of the Medusae. The tentacles are, like those of
Physalis, hollow tubes, and some of them are provided with thread
cells, and sting severely. They have at their extremities and sides
sucker-like processes by which to retain a better hold of their
victims, or, as is supposed by some, to enable them to anchor, and

Fig. 122.— Willsia stdlata (after Forbes), seen from above— a, star-like ovarium ; 6, radiating
canals dividing and opening into marginal canal c; d, velum ; e, ocelli (magnified).

"rest and be thankful," when so disposed. Some of the Medusae
attain a large size, like the Ehizostoma Cuvieri mentioned by Mr.
Francis as having been found by him on the Cornish coast, and
recorded in the Field of May 19, 1866. I append a figure of
this monster Medusa, whose umbrella, in Mr. Francis' example,
was two feet across and dependent polypites the same length
(Fig. 119, p. 94).

The Medusae are divided into two sections, according as the ocelli
or lithocysts above mentioned are naked or covered. The former
have been well described and figured by the late Professor Forbes in
a work published by the Bay Society.

None of the " naked-eyed " Medusae have the power of stinging
the human hand, though it is probable their thread cells may be able
to pierce more delicate structures. In the " covered-eyed " Medusae
the ocelli are concealed by membranes or hoods. And two of the
families, owing to the absence of the velum — viz., Pelagia and

THE LOWER FORMS OP LIFE. 97

Bhizostoma, are placed by many systematists in the next and last
order, the Lucerniadae.

Among the covered-eyed species of Medusae, two species are very
common on our shores. First, Aurelia aurita; this when seen
floating through the water is readily distinguished by four crescent-
shaped purple markings, which are discerned through the gelatinous
disc or umbrella. This species is very abundant all along our
coasts, sometimes, as Forbes remarks, impeding the progress of boats.
I need not figure it, as any one may get it for himself. It does not
sting.

The other common species on our coasts, Cyanea capillata, does,
however, sting severely. It is distinguished by its flatter disc, " bf
a pale yellow colour, deeply scalloped at the margin into sixteen
quadrate lobes, between each pair of which in a deep notch is a
conspicuous pedunculated ocellus. Eight brownish rays proceed
towards these ocelli from a circle of reticulated, quadrate, brown
markings, giving the whole disc a beautifully stellated appearance,
which depends on the organs on the sub-umbrella, which is fur-
nished with long plicated and furbelowed membranous arms and
fasciculi of extremely extensile stinging filamentary tentacles"
(Forbes).

The Medusa which I illustrate at Fig. 118 (p. 93) is a species which
has been taken occasionally on our shores, but is well known to those
who have sailed on the coast of Italy, where it looks, owing to its
phosphorescence, like a ball of fire in the water. It is a very beau-
tiful creature. The disc is of a rich rose colour speckled all over,
especially at the sides, with orange-coloured warts. Its margin is
divided into sixteen lobes, from beneath eight of which spring eight
long tentacles, while in the remaining grooves are eight red covered
and stalked ocelli.

The species as shown by Fig. 119 (p. 94) deserves one or two
remarks. As a rule, the appendages which hang down from the
centre of the umbrella are connected with the polypite, whose
mouth they cover and provide with food. In Ehizostoma Cuvieri,
however, the arms end in distinct polypites, each having a small
opening or mouth at its extremity ; this is the commencement of
a canal which, after dividing freely in the arms, terminates in a
large stomach which is covered in by the second tier of fringes in
the figure. It has no other digestive apparatus. The stomach is
not yet even free, but remains, as in the Hydra, a hollow in the
substance of the polypite, with its inner and outer skin.

There are six genera of "covered-eyed" Medusae described as
occurring on our sea-shores, but the number of species is only eight
or nine. Chrysaora hysoscella has curious ribbon-like appendages,

H

98

POPULAR ILLUSTRATIONS OF

.which float at great length in the water, mingling with a large
number of marginal tentaculse. The disc " is yellowish or reddish,
marked with more or less distinct pale rays, and often spotted with
brown at the margin " (Forbes).

Of the "naked-eyed" Medusae, Forbes has described eighteen
genera and figured forty-three species in his beautiful monograph
from which I have already quoted.

Fig. 123.— Lucernaria campanulata, as seen from above, and in profile — a, mouth of polypitej
5, tentacles ; c, hydrorhiza, or root of polypite ; d, the umbrella ; e, seaweed.

The Lucernaridae are the last group of the Hydrozoa. I propose
to restrict them, without going into the question of classification, to
those known as constituting the family Lucernariadse, in which there
are no ocelli, and which have the umbrella everted and fixed by
a hydrorhiza, as shown in Fig. 123. These small but beautiful

THE LOWER FORMS OF LIFE. 99

organisms appear like Medusae turned upside down, being generally
about an inch in height. Their attachment by the hydrorhiza (a)
is not permanent. As shown in the figure, the tentacles (5) are
eight, sometimes nine in number, and appear like tufts of flowers
round the rim of a glass vessel.

The granular matter of which these organs of prehension are
composed passes between membranous folds and terminates in a rim
surrounding the mouth of the polypite (a). In another genus,
Carduelia, these tentacles form a complete rim round the edge of
the cup. They have generally sucker-like appendages at their
extremities ; but in others they are club-shaped, like those in the
Zoophyte, Coryne.

The Lucernaria are of a pink colour, and can close in their cup
by the contraction of a series of muscular fibres which pass round
its rim and radiate towards the polypite (a, Fig. 123). By the
alternate opening and shutting movement thus produced, they some-
times swim through the water, with their cup everted, in a respectable
Medusa-like fashion. Most of the writers since Johnston's day have
copied his figure of Lucernaria auricula. It is only fair, therefore,
to give his other figure, L. campanulata, a like chance of popularity,
which I have accordingly done.

CHAPTEE V.

REPRODUCTION OF THE HYDROZOA.

THE Phosphorescence of the Sea is a subject of sufficient interest
and importance to merit a short space before we close the history of
the Hydrozoa.

Almost all the Medusae and Physalia and some of the corallines
among the Hydrozoa are phosphorescent, and no one can have
witnessed this phenomenon, even as seen on our own shores, without
being struck with its singular and weirdlike beauty. In other
countries it is even more striking.

Mr. Bonnycastle thus describes a scene of this kind which he saw
on the 7th of September, 1826, in the Gulf of St. Lawrence : —

" While it was very dark a brilliant light, like that of the aurora,
was seen to shoot suddenly from the sea in a particular quarter. It
spread thence over the whole surface of the water between the two
shores of the gulf, and shortly there was presented one blazing sheet
of awful and most brilliant light, in which many large fishes were

H2

100 POPULAR ILLUSTRATIONS OF

seen darting about as if in consternation. The light was sufficient
to enable me to see the most minute object on deck. On drawing
up a bucketful of water and stirring it with the hand it presented
one mass of light, not in sparkles as usual, but in actual coruscations."
— Trans, of Literary and Historic Society of Quebec.

The animals chiefly concerned in marine luminosity are those
we have already dealt with. The most common, perhaps, of all
is a small animalcule which occurs in countless myriads in
the sea — viz., the Noctiluca miliaris. This curious creature is
one of the Amoebae. After the Noctiluca the Ccelenterata supply
the greatest number of light-giving creatures. When individual
objects are discerned the phosphorescence is caused generally
by one or other of the covered-eyed Medusae or Pelagia, and the
scintillations so often noticed are produced principally by one of
the small . naked-eyed species — viz., Thaumantias lucifera, a beau-
tiful creature about the size of a split pea, having round the rim
of the umbrella no less than eighty-four tentacles. As to the
cause of phosphorescence a great deal has been surmised. All
modern scientific observers agree in the fact that it is produced by
animal motion ; that it is therefore a vital act, and not a consequence
either of slow combustion or the production of a phosphorescent
body or mucus. The light is clearly •electrical. Kolliker believes
that the luminous organs are a nervous apparatus similar to the
electrical organs of fishes ; but this presupposes the existence of a
nervous eystem in animals where it has not been discovered by the
strictest examination. The one great and prominent function of the
sarcode of the Amoebae is, as we have seen, that of motion ; and
this sarcode is differentiated in the higher animals into muscular
tissue. It is not, therefore, very difficult to understand how such
motion may be accompanied by electrical discharges, and thus
constitute the phenomenon known as phosphorescence.

In the Medusae it is probable that the light is more or less con-
nected with the discharge of those curious thread cells of which I have
said so much. Forbes remarks that he never saw phosphorescence
in the naked-eyed Medusae spring from any part of the body except
the tentacles, and all writers refer to the lithocysts as more or less
connected with the phenomenon. Now, as we have seen, these parts
of the bodies of Medusae are the principal seat of the thread cells,
and the inference I have drawn is, I think, supported by the fact
that a Medusa, when fresh caught, will emit light when irritated,
but that by a repetition of the process the power soon ceases,
which would naturally be the case when all the thread cells were
discharged. Forbes, however, says that none of the naked-eyed
Medusae have the power of stinging. But it must not be inferred

THE LOWER FORMS OF LIFE. 101

from this that they have no "thread cells," as they would in such
minute creatures evidently be too small and delicate to pierce the
thick human skin. It is certain, however, that the genera Turris,
Oceana, Dianea, and Thaumantias are all phosphorescent. This
phosphorescence must not be confounded with that produced by
terrestrial animals like the glowworm and lantern fly, in whom a
special apparatus exists, and which is evidently designed, in the
one case at least, to guide the male to its mate. The same result
may be produced by very different means, and we often see this
in our study of Nature and her laws. All analogy points to the
probable inference that the power of emitting light is given to the
lowly and graceful Medusa as a means of protection from danger.
The subject is one of interest and importance, and I commend it to
the study of those who have the time and opportunity for such
investigation.

THE EEPRODUCTION AND DEVELOPMENT OF THE HYDROZOA next
claim our notice, and the facts to which I beg the particular attention
of those who study natural science are very curious and interesting.
I have before detailed one of the modes by which the common fresh-
water Hydra is reproduced — viz., from buds like a plant. But the
creature which thus increases itself by buds was itself the product
of an egg ! Such at least, I ought to have said, might have been
its origin, for the Hydrse multiply by eggs as well as buds. Yet a
third way remains to be mentioned by which these singular creatures
can be reproduced. They can divide themselves into one or more
parts by what is termed fissiperation. "We are told by a German
writer, Jager, that he has observed specimens which he had kept
warm divide themselves into different portions, each of which
became encysted like Vorticella (ante, p. 33). Jager suggests that
these encysted portions of Hydrse would hybernate in this con-
dition, and in the spring each would come out a veritable fully-
formed Hydra. Although Jager has not, I believe, substantiated
the truth of this suggestion, all analogy gives it a higher degree of
probability. A great deal of the surprise which these statements
create is removed when it is considered, first, that all eggs or ova are
more or less of the nature of buds themselves ; and, secondly, that
even as high in the scale as insects, the development of young may
take place by internal budding without the direct intercourse of the
sexes.* Every practical entomologist knows this. Bearing these
facts in mind, let us look at the details in the life history of the

* This fact, as far as the aphides are concerned, has been lately rendered
doubtful by the experiments of the physiologist Balbiani, who considers all tho
apterous aphides as true hermaphrodites.

102 POPULAR ILLUSTEATIONS OF

next family of the Hydrae, the Corynidee. In these and other
Zoophytes, as well as in the Calycophoridse and Physophoridse, the
germs are carried in a large conspicuous cell (Fig. 102, /, ante, p. 79,
and pp. 81, 82, 84), which, by reason of its office as a bearer of
germs, has been called by Professor Allman a Gonophore. Fig. 124
represents the Gonophore of one of the club-shaped Zoophytes full
of young germs. Fig. 125 shows us the same Gonophore after it
has opened at one end and given exit to the embryos within it, one

Fig. 124. Fig. 125. Fig. 126. Fig. 127. Fig. 128.

of which, provided with a row of cilia by which it can swim through
the water, is seen at Fig. 126. By and by we find it assuming a
pear-like form, as seen at Fig. 127, and then becoming attached,
as shown at Fig. 128, it is developed into a primitive polypite
(Fig. 129), which is the founder, by budding, of a colony similar to
that seen in the corallines, and which I fully explained, and illus-
trated, ante, pp. 79-84. All this was beautifully worked out by
Professor Allman, and published by him in the Philosophical Trans*
actions for 1863.

Fig. 130. Fig. 131. Fig. 132.

In the Sertularidae the changes are still more interesting. In
these Zoophytes the Gonophores (Fig. 104, p. 81) contain germs
which are exactly like Medusae, and have, in fact, been taken for
such by naturalists. These Zooids, as they have been termed by
Professor Allman (Fig. 130), after swimming about by means of

THE LOWER FORMS OF LIFE. 103

their cilia, become at length fixed, and after a time have the appear-
ance of flattened discs (Fig. 131) surrounded with a close fringe of
cilia, and showing a tendency to divide in four places. This disc
becomes, in fact, the root or hydrorhiza, and from the centre is
developed the first polypite (Fig. 132), which by budding grows into
the tree-like Zoophyte or coralline which we pick up on the sea-
coast, and magnified drawings of which I have given ante, pp. 79,
81, and 82. While the facts connected with the reproductive
phases just described are fresh on the memory, let us follow out
the life history of one of the Medusididae.

It will be remembered that, in describing these forms in the last
chapter, I pointed out (i, Fig. 120, p. 95) a swelling in each of the
radiating canals just before it terminates in the marginal canal. This
is the reproductive body, which contains the eggs or embryos. These
when first emitted are covered with a gelatinous investment, and
have the appearance shown at Fig. 133, but which in a free con-
dition are like Fig. 134. The product of one of these eggs is an
animal known to naturalists as an hydra-tuba, and in its early or
very young state is represented at Fig. 135 with four marginal
tentacles in the process of development. In a short time these
tentacles become doubled, and the creature fixes itself by its hydro-
rhiza, as seen in Fig. 136. The mouth now becomes enlarged, the
tentacles again divide, and the creature becomes, in fact, as nearly
as possible a fac-simile of the fresh-water Hydra (Fig. 137), in which

Fig. 133. Fig. 134. Fig. 135. Fig. 136. Fig. 137.

condition it may remain for years, budding and sending off young
Hydree exactly as the Hydra does. But all this time it is only in a
transitional condition. We must not forget that we are talking now
of the product of an egg deposited by one of the large Medusae, or
so called " jelly fish."

The intelligent reader will also remark that while the corallines
in their development pass through the form of Medusae, these latter
return the compliment by assuming the form of the polyp. This
constitutes what is termed parthenogenesis, or alternation of genera-
tions, in which the child is never like its parent until it has passed
through a period of existence of indefinite length, during which
period it gives birth or origin to other beings like itself, all of which,

104

POPULAR ILLUSTRATIONS OF

by another series of changes, become developed into a vastly-increased
number of young Medusae lik'e their original parent !

We will follow out these changes by the assistance of Steen-
strup's figures in the memoir which first brought the subject prac-
tically before the scientific world, although Sars and Chamisso were
those by whom the facts of parthenogenesis were originally eluci-
dated. Steenstrup's work was translated by Mr. Busk, and pub-
lished by the Bay Society in 1845, since which time its illustrations
have been generally made use of by naturalists, and very often
without the slightest acknowledgment.

At a period, then, in the existence of the polyp shown at Fig. 137
(p. 103), which is unknown, and influenced by the operation of a law
which is constant — although the nature of the force which brings the
law into operation is also unknown — this polyp shows a tendency to
divide just below the insertion of the tentacles. Instead, however,

Fig. 138.

Fig. 139.

Fig. 140.

Figp. 141, 142.

of dividing at once, the body of the polyp increases in size in an
upward direction, showing as it does a series of distinct circular
markings (Fig. 138). After a time it presents the appearance
shown in Fig. 139, where it will be observed each circular marking
has become crenated by the growth of processes having an upward
direction. The animals or larvae now begin to separate. The first
one coming off at a (Fig. 139), which is called by Steenstrup the
" polypiform nurse," becomes fixed by a root or sucker-like extension
in the centre of the umbrella, and is termed by him a " stationary
Medusa."

Leaving, however, the history of this " stationary Medusa," we
find that, after it has separated, the pile assumes the form of
Fig. 140, which is nothing more nor less than a series of young
Medusae, having now no connection with each other, but which
speedily separate and grow up into the full-grown "jelly-fish."

THE LOWER FORMS OF LIFE. 105

When first separated they have the appearance shown at Fig. 141,
but speedily appear as at Fig. 142, with their umbrellas and tentacles,
and grow up gradually until they attain the form and size described
and illustrated in the last chapter.

Such are some of the remarkable facts connected with the repro-
duction and development of the Hydrozoa. M. A. De Quatrefages,
in an admirable little book, " The Metamorphoses of Man and
Animals," which has been well translated by Dr. Lawson (Hard-
wicke), goes fully into the curious subject of alternation of genera-
tion, and concludes his fourteenth chapter in the following words : —

" What would our readers think were we to express ourselves
thus ? A butterfly deposits an egg from which springs an earth-
worm that is soon converted into a caterpillar. From this cater-
pillar a series of buds are produced which become so many indi-
viduals like the first one ; then each of these, although preserving
the caterpillar head, assumes the body of a chrysalis ; this body is
constricted at intervals, and gradually becomes converted into a
cluster of butterflies piled up one upon another; the caterpillar head
then falls off, and the butterflies fly away one by one. At first they
resemble moths, but by degrees they assume their true characters,
and become beautiful diurnal Lepidoptera. Who would put any
trust in a history which described a series of transformations as
fantastic as those seen in a dream? Yet change a few of the
expressions, employ the terms Acalephae, and Medusas for those of
insects and butterflies, and that which a moment before had been
fiction becomes simple truth."

CHAPTER VI.

THE ACTINOZOA.

THE Actinozoa form the second division of the Coalenterata, and
they are at once and definitely distinguished from the Hydrozoa by
possessing a stomach which is freely suspended in the body of the
animal ; whereas, as I have already pointed out, this organ in the
Hydrozoa is merely hollowed out, as it were, in the substance con-
stituting that creature's corporeal structure. This is not a mere
fanciful distinction raised up by arbitrary classifiers to make their
arrangements more definite ; it is a great step in the upward
progress of the living being towards that perfection of structure
which we see in man and the higher animals. I dot down the

106

POPULAR ILLUSTRATIONS OF

great points as we go on in order that those who take an interest
in these illustrations may mark, learn, and inwardly digest the
great plan upon which living structures are built up. Henceforth,
then, in the scale of life we shall find a free stomach in the subject
of our study. It is the first truly differentiated organ we have
hitherto met with ; and this fact will be impressed on the reader's
mind evermore if he will note therein that this occurs in the
Actinozoa, and that the type of this division is the well-known sea-
anemone of our coasts.

But, to assist his memory, I will give diagrams illustrating the
difference in this respect between the Hydrozoon and the Actinozoon.

iS

d

Fig. 143.
Longitudinal Section of Hydrozoon.

a, mouth — b, stomach — c, endoderm— d, ectoderm— e, tentacles.

Fig. 144.
Transverse Section of same.

Fig. 145.
Longitudinal Section of Actinozoon.

Fig. 146.
Transverse Section of same.

«, mouth— 6, stomach— c, endoderm— d, ectoderm— e, tentacles-/, lamellar plates, or
mesenteries, which divide the somatic cavity into what are termed—/, loculi- h, ova or
germs -sr, body containing thread cells— i, opening of stomach into (£) the somatic
cavity.

Fig. 143 is a longitudinal section of a Hydrozoon, and Fig. 144 a
transverse section of the same ; while Figs. 145 and 146 represent
similar sections of the Actinozoon. The letters indicate the same
parts in each figure. Now, mark that the stomach (b) is in the
Hydrozoon hollowed out, as it were, of the body substance, while it

THE .LOWER FORMS OF LIFE. 107

is seen suspended into the somatic cavity in the Actinozoon. The
stomach of the former is only separated from the external world
by the endoderm (c), the ectoderm (d), and the intervening sarcode.
In the latter there is seen at k a wide space between the free
depending stomach (£) and the body wall at c d. And this space is
found to be divided into partitions, which are occupied by certain
organs (g h), and communicate above with the hollow tube called
the tentacle, as diagrammatically represented at e. Now, a brief
examination of these partitions and organs will reveal to us the
morphology of the Actinozoon, and show us how far upwards we have
now reached in the scale of organised nature.

From the mouth (a, Fig. 145) is seen dependent the stomach (5),
in a kind of hollow formed between the inner plate of the partitions.
At i the stomach opens into the somatic cavity (k), where the
digested food serves the purposes of nutrition, the useless reliquiae
being returned through the same opening.

Now, in this lowly and beautiful flower-like animal there are
shadowed forth structures which are fully developed in the higher
class of animals. Let us illustrate this :

The body wall (c d, Fig. 145) consists of two membranes, the ecto-
derm (d) and the endoderm (c), and between them, as shown by the
lines, are two distinct classes of muscular fibres, by which the animal
contracts or dilates itself at pleasure. The ectoderm (d) is, however,
itself divisible into two membranes, the outer one resembling the
epithelium, and the under layer the derma, or true skin of the
higher animals ; and between these layers of skin are imbedded
vast numbers of thread cells and the pigment granules by which the
beautiful colours of the anemone are produced. The endoderm (c)
may also be separated into two layers, one of which is in contact
with the muscular structure ; the other is free, and forms one of the
boundaries of the partitions, as seen at c (Fig. 146). Both the endo-
derm and ectoderm have their free surf aces covered with the hairlike
bodies, which I described in a former chapter, termed cilia. The
stomach is a simple thin sac, also of two layers, having its inner
surface covered with cilia (b, Fig. 145).

In the muscular structure between the endoderm (c) and the ecto-
derm (d) we have a foreshadowing of that important part of animal
organisation which we know so well in our own bodies. There are
two kinds of muscle in this covering of the Actinozoa — a longi-
tudinal series of fibres deeply seated, and a circular series, superficial.
Each of the partition walls (/, Fig. 146) has two muscles on its
surface, and the muscular fibres of the stomach enable the opening (i)
to close or open at the will of the animal, while the tentacles (e e) are
moved by similar structures. The contraction of the animal itself and

108 POPULAR ILLUSTRATIONS OF

its dilatation, which most people have often observed, is due to the
alternate action of the horizontal and circular fibres. By examining
the diagram the student will observe that both the tentacles and
the stomach are prolongations of the body wall, and therefore are
similarly organised. At h, Fig. 145 (p. 106), is shown a string of
beadlike bodies, which are ova, as seen in the female ; for, although
the Actinozoa aie propagated both by budding and fissiperation,
there is also a true mode of reproduction by sexes which in the sea-
anemones are distinct, although not recognisable by any external
character or any mode of examination except that of the bodies seen
at h by the microscope. At g, Fig. 145 (p. 106), are shown what
represents the convoluted filamentary bodies, which contain thread
cells, and which the animal can emit outwardly through minute
orifices in the skin, called by Mr. Gosse "cinclides."

In translucent specimens of the sea-anemone, the six partitions
formed by the six lamellae (/, Fig. 146, p. 106) can be clearly seen,
and it may also be observed that these lamellae do not go to the bottom
of the somatic cavity ; consequently, the spaces formed by these
" mesenteries," as they are termed, all communicate most freely with
each other. A nervous system has not been yet discovered in the
actinea, or sea-anemone ; but as it undoubtedly exists in some of the
other Actinozoa, it probably only awaits the discovery of some
worker more successful than any has hitherto been. In the margin
of the disc of the sea-anemone there are sometimes observed some
bright blue specks, which have been thought to be organs of vision,
of course in a very rudimentary condition.

The thoughtful reader will not fail to remark that we have now
arrived at a decided step in advance in the organised scale of animal
existence, not only in the existence of a free stomach with a
sphincter, or muscular structure, by which the opening of the
stomach into the somatic cavity (z, Fig. 145, p. 106) is closed and
opened according to the necessities of the creature's existence, but
also in the differentiation, as it is termed, of the sarcode, of which we
have spoken so frequently in our previous chapters, into a system
of muscles having both flexor and extensor fibres — not as we see in
the Calycophoridae, merely in the formation of an apparatus for the
special purpose of locomotion, but pervading the whole body, sub-
stance, tentacles, and stomach of the animal.

Now this word differentiation simply means a fact which we
cannot explain. Sarcode is the ultimate pabulum, or basis, of all
animal structure. It not only exists in the lowly Amoeba, but is the
main constituent of all animal bodies. By the vital principle this
sarcode is changed, or altered, or differentiated into muscle, bone,
brain, nerves, blood vessels, tendons, lungs, heart, and all the alimen-

THE LOWEE FOEMS OF LIFE. 109

tary and other abdominal organs of man himself. But of the
essence or nature of the vital principle we know nothing. The
physio-chemico philosophers of modern days have endeavoured to
identify it with correlated force, and to compare it with the power
which forms the dead crystal. With what success this has been
done may be found in the new edition of Todd and Bowman's
" Physiology," where the masterly genius of Professor Beale has
shivered such a notion into a thousand atoms, none of which will
ever again gain either power or coherence. No ; the vital principle,
the first puzzle of all writers, is an ultimate fact which cannot be
explained by a finite mind. Chemical force can, by its power of
attraction, select the object with which another combines, and the
result is a crystal and a definite thing in nature ; but that force
cannot say to the dead crystal, live, and feel, and move, and think.
Neither can such a force say to the ultimate structure or cell, when
living, grow and form muscle, or nerve, or bone, or brain. The
Power which does this is incomprehensible to the human mind, and
it is simply because the finite can never, from the nature of things,
comprehend that which is an attribute of the Infinite.

The sea-anemone is a pleasing study to the sea-side naturalist,
and to those who in their aquaria have a miniature sea in their
drawing-room. This is a subject over which the genius of a Gosse
lingers gracefully, for has he not written a book which leaves little
or nothing to say of all the family ? — and has he not told us " who
is who," and given us beautiful portraits of the various branches,
relations, and connections of the Actiniae? Perhaps what I have
written may give an additional interest to the study of his book,
for it is surely not my intention, even had I the space, to attempt
any extracts from its pages.

But we will follow the sea-anemone from the coasts of Devon to
the soft balmy seas of the Pacific, and we will there show how great
and important an agent it has been in the formation of the world.
We will look into the clear deep blue sea, and search there for its
whereabouts, and, if the eye is gladdened and the fancy charmed by
the panorama we witness, we shall not be in a less fitted state of
mind to ponder upon the grand facts which the history of the Coral
will unfold. The very name is suggestive, and its utterance carries
us back mentally to the days of our boyhood, when the mere sight
of those beautiful masses of curiously-wrought limestone used to
transport us in imagination to the Cocoa-Nut Islands and the fierce
savage of the Southern Seas, of which we had read in those thrilling
tales of adventure like Eobinson Crusoe, which make such an impres-
sion on the youthful mind. How often, too, do we look upon the
carefully-tended glass-covered specimen as a link which connects us

110 POPULAR ILLUSTRATIONS OF

with the past, and perpetuates the living memories of some dear
friend or relative who has long since found his rest in the deep sea.
But there is no part of the interest attached to the Coral of greater
significance than that which we shall find connected with its history
in the formation of the crust of the earth. The thousands of islands
which, for the space of sixteen millions of square miles, are found in
the great Pacific Ocean are almost entirely formed of Coral. All the
north-east coast of New South Wales for upwards of one thousand
miles has a barrier reef of Coral. In the Indian Ocean the immense
chain of islands known as Cosmoledo, Saya de Malha, Chagos, the
Maldivas, and the Laccadives, are all formed of Coral, occupying a
space of nearly two thousand miles. The eastern coast of Africa,
from Mozambique nearly to Ajan, upwards of one thousand miles, is
an immense fringing reef of Coral. The coasts of the Bed Sea are
almost entirely Coral. Turning again to the Indian Ocean, we find
the south-west coast of Sumatra and the southern coast of Java
fringed with Coral. From the northern extremity of the Celebes to
the Philippine Islands, thence to Bashee, Patchow, and Loo Choo,
and back again into the China Sea, we find the Paracells and other
large islands all formed of Coral ; and, lastly, for I need not continue
the detail, the islands of Bermuda and the West Indies are sur-
rounded by fringing reefs of Coral.

This rapid glance at the works carried on in the present day by
the polyp which forms the Coral, will give some slight idea of the
immense importance which this creature has possessed in fashioning
the form of the earth's surface. If we go below this and look at
the records of its working in time, our astonishment will be vastly
increased. Some of the most interesting problems connected with
the age of the world are solved by these records. Before, however,
I enter into this part of the subject, we will inquire who and what
this wonderful architect can be ?

The answer is very simple. None other than a minute variety, or
near relation, of the sea-anemone, whose life history we will indite
in our next chapter.

THE LOWER FORMS OF LIFE.

Ill

CHAPTER VII.
CORAL.

THE Actinozoa are divided into four orders. The first of these, the
Zoantharia, comprises the sea-anemones, including the small variety
which builds coral reefs ; the second, called Alcyonaria (because
the typical species was at one time presumed to be the hardened
foam of the sea wherewith halcyons build their nests), is repre-
sented by the polyp which forms the well-known red Coral of
commerce, the curious horny Coral known as the " Sea-Fan" or " Sea-
Pen, " and still more popularly by the leather-hardened foam-looking
masses which the sea-side rambler recognises as " Cow Paps " or
" Dead Men's Fingers ;" the third order is constituted of an extinct
fossil family of Coral builders, the Eugosa ; and the fourth and
most highly organised is called, by reason of the serrated or comb-
like appearance of some of the species, the Ctenophora, all the species
of which are oceanic and free.

I will say a few words about the order Alcyonaria first, because
the species which form it build up their Coral skeletons in a different
manner to that which is adopted by the Zoantharia. There are, in
fact, two great plans upon which Coral is formed, and I will shortly
illustrate both of them.

Fig. 147.— Sclero-basic.

Fig 148. Fig. 149.— Sclero-dermic.

Fig. 147.— a, Coral secreted by outer skin of the base of the polyp, and extending from

below upwards.

Fig. 148.-Coral formed by this means as seen in red Coral of commerce.
Fig. 149. —a, Coral secreted from the inner skin, and extending from without inwards, as in

reef-building Corals.

The figures 147 and 149 represent two ideal or diagrammatic
longitudinal sections of Actinozoons, the former being one of the
Alcyonaria, and the latter one of the Zoantharia.

112 POPULAR ILLUSTRATIONS OF

Now, by the vital force inherent in the polyp, a power over which
the creature has no control, there is formed by the outer membrane,
or ectoderm, a calcareous mass, which I have marked a.

We will suppose that the polyp has just arrived at polyphood,
if I may coin a word, and is about to become the founder of a
great colony of polyps. Well, then, having formed a starting point
at «, the polyp increases itself by buds, or self -division ; and the
progeny, connected with each other and their respected parent by
an extension of the ectoderm constituting a coenosarc, also secrete
Coral.

The form, the fashion, the direction of this secreted Coral are
determined by the individual necessity of the polyp family. In one
case it rises up a column like that of Fig. 148, which divides like a
tree, the stem and branches being equally covered by the compound
Actinozoon. When taken from the bottom of the sea and the " live
flesh " cleared off, this turns out to be the red Coral of commerce, of
which our shirt-studs- and ladies' ornaments are made.

Another species prefers horn to lime, and forms the beautiful
skeleton known as the Sea-Fan (see frontispiece) ; while still another
species, having, I suppose, a literary taste, shapes its skeleton in the
form of a pen, which shines at the bottom of the sea with a phos-
phorescence brilliant and beautiful to behold (Fig. 164, frontispiece).

Now there are three facts to be noted by the student in reference
to the Alcyonaria polyps.

First, they have eight tentacles or multiples thereof. Secondly,
that, although the Coral appears to be within the living mass of
polyps, being secreted by the outer skin, it is in reality outside the
animal ; and, thirdly, being formed by the basal part of the animal,
and the Coral being very hard, naturalists have called the mode of
its production by the name of sclero-basic (from skleros, hard ; and
"base").

If, however, the student prefers it, he may remember this, accord-
ing to Dana, as Coral formed lay foot secretion ; not that the creature
has a foot, but simply that the part of its body which secretes the
Coral performs the office of a "foot."

Now, if you please, just transfer your attention to Fig. 149,
which is another diagrammatic section of a Cqral polyp, and of by
far the most numerous family, among which are the Coral reef
builders.

Observe that the skeleton is formed in this section by the inner
skin, or endoderm, and that it extends from without inwards, follow-
ing, in fact, the course of the partitions or mesenteries which I illus-
trated in the sea-anemones in the last chapter, and which may be
further seen in the transverse section of a corallurn (Fig. 151, p. 115).

THE LOWER FORMS OF LIFE. 113

Now, it follows as a matter of course that as the Coral is secreted by
the inner skin, it must, of necessity be inside the polyp ; and it
is called, by reason of its mode of formation, sclero-dermic, while
the number of tentacles, and therefore of partitions, is always five
or six, or multiples of these numbers. This mode of coral forma-
tion is also called by Dana "tissue secretion." In a living state
the Coral in this section is also hidden by the compound animal,
each polyp being connected by an extension of the internal layer of
skin, or coBnosarc.

It is by Corals of this division that all reefs and most of the
specimens in our collections have been formed. If the reader will
take up one of the species which he may have in his possession, he
will observe that it is made up of a number of cells, having their
lamellae, or plates of carbonate of lime, crossing each cell in regular
order, and forming five or six partitions or multiples thereof. A single
cell of this kind is called a corallite, and several of these together a
corallum, while, just as the flesh which connects the polyp is called
a coenosarc, so the carbonate of lime which connects the corallites of
a corallum together is called a ccenenchyma (koinos, common, chyma,
tissue). The entire calcareous substance of a Coral is called
" sclerenchyma." It must be borne in mind that, however large the
corallum, it has been formed by successive layers of polyps. Life
and death, as in all organised nature, carry on their operations side
by side. Each layer of polyps, having fulfilled their allotted duty,
increase by budding or division, and die, while their progeny rear
up a new stratum of Coral upon their remains. And this process
goes on till vast masses of dead with a thin stratum of living Coral
on its surface are formed. Thus the result may be the specimen on
your chimney-piece, a small island, a reef 1000 miles long, or a vast
continent like that supposed to have sunk in the Pacific Ocean,
millions of square miles in extent. " What vast industry is here
exhibited ! " I fancy I hear some one exclaim. Not in the least. I
am sorry to destroy such an illusion, for, in fact, our friend the Coral
polyp is a bit of a sensualist, and passes his whole life with no
care of the morrow and no thought of the past. The whole object
of his life is to secure food and open his flower-like tentacles and
bask in the blue waters which are warmed by the tropical sun. The
Coral is made without the slightest effort on the part of the polyp.
It is secreted just as our bones are secreted, whether we will or no.
It is a process of life, guided by the laws of life, and perfected by
the forces of life. But notwithstanding, as we shall hereafter see,
this humble organism, like the Amoeba of the Laurentian rocks, has
been a mighty architect in Time.

Let us now examine into the minute structure of Coral, and take

114 POPULAR ILLUSTRATIONS OP

a peep at the life history of its builders. We shall then be better
prepared to inquire about reefs and lagoons, and the coral islands of
southern climes.

I have already described the sea-anemone, and stated that the
Coral polyp is a diminutive variety of the same order, Actinia.
Dana, a well-known American author, compares the Coral polyp to
an aster, and the analogy is a very good one. The tentacles open
out in a circle, and are often richly coloured, and the central disc
of different tints gives a very good imitation of the China aster.
Instead, however, of the stalk of the flower, we have in the polyp a
broader pedicil containing the stomach, somatic cavity, and lamellar
tables, as seen in the sea-anemone.

In natural history we always, or almost always, find a connecting
link between distinct groups, leading, as naturalists say, from one to
the other. Between the " hard basic " and " hard skin " groups of
Corals this transition is effected by a clove-shaped Coral, well known
as Caryophylla. This is a sclero-dermic Coral, and the transverse
divisions seen in the figure (No. 171, frontispiece) indicate dead
Coral, the only live portion being that at the end, where the polyps
are expanding. This is quite distinct from the tree-shaped red coral
stem, which forms the axis round which thousands of polyps and
their coenosarc are placed, increasing their stem both in thickness and
length. To illustrate the history of a reef Coral, we will, however,
take a more typical example. Well, then, let us suppose that the
polyp of a large family, called, from their star-like appearance,
Astrea, deposits an egg ; this egg is developed into a young polyp,
having cilia, by which it moves through the water, as we have seen
in the young Sponge. Having swum about and increased in stature,
the young polyp fixes itself in some spot which its instinct tells it
will be most convenient for its future success in life. Having once
become fixed it lays the foundation of a colony, and it may be of an
island or a continent, as we shall see by and by. Without any
power or exertion of its own, the vital force inherent in its nature
selects from the food taken into the stomach carbonate of lime, and
with this it forms on the sclero-dermic system — not, mark, as many
suppose, a house for the polyp to live in, but a beautiful, strong, and
permanent calcareous skeleton, by which the delicate form of the
polyp may be supported and protected. This is termed a corallite,
and the creature now increases, as far as its own colony is concerned,
either by dividing its own body, termed fissiperation, which takes
place at the base, or more frequently by buds springing out from its
side ; each bud or each divided portion forms into distinct polyps,
which increase themselves with great rapidity in the same way, and
each having secreted its corallite, they form in their totality a corallum.

THE LOWER FORMS OF LIFE.

115

It is quite evident that after a time the first race of Corals can
extend no farther. They then die, leaving behind them a progeny
which cover the old Coral of their parents. This process is repeated
in some species indefinitely, each colony of course increasing the size
of the corallum. In others, as in the well-known " Brainstone Coral,"
the size of the mass is limited. I have a fine specimen brought
from Bermuda by Monsignor Virtue, and kindly presented to me,
which is 54 inches in circumference and 30 inches from point to
point over the apex. This is among the largest specimens.

I will now give two diagrammatic sectional figures of a corallite,
one of the common reef-builders, which will illustrate the mode by
which all sclero-dermic Corals are formed.

Fig. 150.— Longitudinal Section of Corallite.
(Sclero-dermic.)

Fig. 151.— Transverse Section of Corallite.
(Sclero-dermic.)

a a, Calice or cup— &, external wall or theca — c, axis or columella (not always present)—
d d, septa, some complete, some incomplete— e e, interseptal dissepimenta— //, tubular
dissepiments— g g, loculi— h h, pali.

It must not, however, be forgotten that the figures are what I say,
only diagrams ; and further, that they represent hard parts laid
down by the inner skin or endoderm of the polyp, and consequently
the internal form of the polyp whose history we are inditing. I am
thus particular because I wish to be clear, and to illustrate this
somewhat complex subject in the simplest form of which it will
admit.

A longitudinal section, therefore, of a corallite (Fig. 150) repre-
sents, as seen at b, an external wall or theca, and an axis or
columella (c), as it is termed, in the centre of the cup-like corallite,
which is not, however, always present.

The figures (a, a, a, a) show the sectional half of the cup or calice
of the corallite. The lines (d, d) indicate the thin plates which are

i2

11.6 POPULAR ILLUSTRATIONS OF

v"

observed to proceed from the external coat (b) to the axis (c). These
are termed septa, and are merely the calcified plates of the Actinia
which were illustrated in the last chapter. Just, however, as we saw
in the sea-anemone that the "mesenteries" were of different classes,
first, second, and third by reason of their falling short, more or
less, in passing through the somatic cavity, so do the septal plates
of Coral, as seen in the diagrams, differ in size just as they approach
more or less near to the axis. Some are seen to go from the theca
to the columella ; others stop short, as shown in both sections by the
dotted lines (h). Where the plates, however, stop short, their place
is supplied by pillar-like deposits, termed "pali," which, being
arranged necessarily in circular rows, are sometimes called coronets.
Some of the septa go through from one side of the corallite to the
other, as seen at f, Fig. 150 (p. 115), without touching the axis.
These are called " tabular dissepiments." Sometimes again, the
" loculi " formed by the septa are crossed by processes, or " styles,"
called " synapticulae," which are seen at e, Fig. 151 (p. 115). These
are called " interseptal dissepiments." I have placed the lines across
at e, e (Fig. 150), just to signify the fact, but of course they would
not be seen in this section as shown in the diagram. The natural
primary division of all zoantharian or sclero-dermic Corals is into
six loculi by six septa. Secondary septa divide these into twelve,
and tertiary septa again divide these into twenty-four, which is the
number I have represented in the diagram 151. • If any further division
occurs the law now alters, and the polyp only produces twelve
additional septa, being two for each primary loculus.

Such, simply, is the structure of Coral. Mark, however, that no
single corallite or species of Coral possesses all the parts as shown in
the diagrams. Some have one kind of dissepiment, some another ;
some have "pali," others have none. A diagram not being a
drawing, we may take the liberty of making it useful by crowding
into it all the forms which are more or less assumed by different
Corals.

When the systematist steps in, he classifies according to the
arrangement of these parts, and makes out a vast number of genera
and species, which fall not within the scope of this work.

The forms thus assumed by Corals are various. I copy the
following descriptions from Dana's "Structure and Growth of
Zoophytes " — premising that in a work recently published this
descriptive and beautiful passage is adopted without even quotation
marks or acknowledgment :

" Trees of Coral are well known : and although not emulating in
size the oaks of our forests — for they do not exceed six or eight
feet in height — they are gracefully branched, and the whole

THE LOWER FOEMS OF LIFE. 117

surface blooms with Coral polyps in place of leaves and flowers.
Shruberries, tufts of rushes, beds of pinks, and feathery mosses are
most exactly imitated. Many species spread out in broad leaves or
folia, and resemble some large-leaved plant just unfolding ; when alive
the surface of each leaf is covered with polyp flowers. The cactus,
the lichen clinging to the rock, and the fungus in all its varieties
have their numerous representatives. Besides these forms imitating
vegetation, there are gracefully-modelled vases, some of which are
three or four feet in diameter, whose symmetrical surface is gor-
geously decked with polyp stars of purple and emerald green. All the
many shapes proceed in each instance from a single germ, which
grows and buds under a few simple* laws of development, and thus
gives origin either to the branch, the broad leaf, the column, or the
hemisphere."

CHAPTER VIII.

COBAL (continued).

THE passage from the Zoophytes or Corallines to the true Corals is
illustrated by the Alcyonaria, which, it will be remembered, are
polyps with eight tentacles or multiples of that number.

In the frontispiece (Fig. 170) is a drawing of the Alcyonium
poculum, or Neptune's cup, which is sometimes, as may be seen in
the British Museum, built up to a large size. These cups are the
skeletons of the polyps, which are seen covering the surface inside
and out with their crenosarc or connecting sarcode. They are found
in shallow water in tropical climates, and were first discovered by
Sir Stamford Raffles upon the coral reefs which surround the
island of Sumatra. The texture of these " cups " is spongy in
appearance and to the touch, but they contain within it numerous
flinty crystalline deposits, which give firmness and solidity to the
structure. These "cups" are sometimes o'f considerable size, as
much as three or four feet high, and two feet broad. Let us next
examine the " Sea-Fan " (Fig. 153, frontispiece). Observe that in
this (as in all but one of the other figures) I have left a part of the
skeleton covered over with the living polyps and their coenosarc, and
I have in this instance drawn one of the polyps relatively larger to
show its general form. Now, these creatures secrete and fashion,
by their vital force, this beautiful arborescent horny network, which
is to serve as the skeleton of the colony. Also remark that the
polyps, as seen in the figure, although to a certain extent enjoying a

118 POPULAR ILLUSTRATIONS OP

separate existence, are intimately connected with, each other by the
sarcode, or fleshy substance called a coenosarc, which is seen between
them in the figure, and upon which they appear to be located.
There is another notable fact in the history of this Coral, which is
that it is always built up with its edges in the direction of the tides.
Were it otherwise — if, in fact, the waves washed against it "broad-
side on," as sailors say — its existence would be of very short duration.
And yet, as I have said before, the instinct of the polyp has nothing
to do with the secretion, the formation, and the mode of position of
its skeleton. All this is the result of a Design quite independent of
the creature itself. Several of these "Sea-Fans" have been found
on our British coasts, but the most beautiful specimens come from
the tropical seas. When the flesh dries it gives various colours to
the polypidom. I have one brought from Bermuda, by Monsignor
Virtue, which is of a beautiful purple colour. The arborescent form,
as seen in the plate, is in these horny Corals singularly exact ; the stem
and branches always bearing the same relative proportions as those
of a tree — another adaptation of strength to resist the forces brought
against it in the sea.

Fig. 154 (frontispiece) also belongs to the Gorgonidae. It is
called the Horsetail Coral, and has occasionally been taken on our
Scottish coasts. It is formed partly of calcareous matter in the
form of lenticular masses, as seen in the plate, which are joined to
each other by thin black horny segments, which give it a jointed
appearance, and the branches are thus enabled to wave about in any
position in which they are placed in the water.

The name of Gorgons given to these horny Corals by Linnaeus
arose from the fancied resemblance of the polyp (Fig. 153, frontis-
piece) to the sea-deity, whose locks were said to have been changed
into serpents by that spiteful goddess Minerva.

Another Alcyonarian polyp, and one which is placed by systema-
tisers before the Gorgonidse, is that beautiful and singular feather-
looking form • seen at Fig. 1 64, frontispiece (Pennatula grisea, or
" Sea-Pen"). This graceful Coral consists of a stem resembling the
shaft of the feather, one end of which is more or less firmly fixed in
the ground, while after growing thick in the middle it terminates
in a thin, finely graduated point. Now, this shaft or axis is formed
more of phosphate than carbonate of lime, and is therefore allied to
bone in its consistence. It is movable at both ends, and is covered
with a coenosarc, which is prolonged on each side into branches,
having a general resemblance to the " barbs of a feather, and
upon these delicate offshoots the polyps are seen, placed in the
upper margin of each. These barbs are supported by a large number
of calcareous spiculae in their interior.

THE LOWER FOEMS OP LIFE. 119

The British species (P. pkosphorea) is very common on our coasts,
especially in Scotland, and is taken in numbers attached to the bait
of the fishermen's lines, especially, according to Ellis, when this
bait is a mussel. It is from two to four inches long, and of a
purple colour, except at each extremity, where it is pale orange.
When irritated it is beautifully phosphorescent. A difference of
opinion exists among naturalists, whether the Sea-Pen is perma-
nently fixed in the ground, or has a certain extent of locomotion.
Grant, after Cuvier, Pallas, and Bohadsch, has adopted the latter
view, and expresses himself about it as follows : " A more singular
and beautiful spectacle could scarcely be conceived than that of
a deep purple P. . phosphorea, with all its delicate transparent
polypi extended, and emitting their usual brilliant phosphorescent
light, sailing through the still and dark abyss, by the regular and
synchronous pulsations of the minute fringed arms of the whole
polypi."

Dr. Johnston, however, in his British Zoophytes, doubts whether
the Sea-Pens have any locomotion, and quotes Lamarck and
Schweigger as authorities in his favour. Johnston, with much
reason, observes, that it is most improbable that a compound animal
so low in the scale should have the power of locomotion, and states
that he has never known them to move their position when placed
in a basin of water. " They inflate the body until it becomes in a
considerable degree transparent, and only streaked with uninter-
rupted lines of red ; they distend it more at one place, and contract
it at another ; they spread out the pinnae, and the polyps expand
their tentacles, but still they never attempt to swim or perform any
effort towards locomotion. Our fishermen believe that they are
fixed at the bottom with their ends immersed in the mud, and the
paleness of the base, when viewed in connection with the preceding
observations, go far, in my opinion, to prove this statement to be
correct."

The phosphorescence of the Sea-Pen proceeds entirely from the
polyps. Fig. 165 (frontispiece) is one of these polyps magnified.

Another of what are sometimes called bark-covered Corals is
illustrated in the plate by a figure of the well-known red Coral of
commerce (Fig. 162, frontispiece), which is produced by an Alcyo-
narian polyp belonging to the genus Corallium. A portion of the
ccenosarc and its polyps have been removed in three places in
the figure, and what is seen laid bare is the bony, calcareous,
richly and variedly-coloured substance of which coral ornaments are
formed. This Coral is found principally in the Mediterranean,
where it forms one of the staple articles of maritime industry.
The somewhat clumsy-looking form in which it grows, as seen in

120

POPULAE ILLUSTRATIONS OP

the plate, is a necessity of its existence, for the Coral is itself
brittle, and were the branches thinner they would inevitably be
broken by the waves. Observe that the exposed parts show
no pits or depression — the surface being perfectly smooth. The
coenosarc is whitish in colour, and the polyps are milk white, and
nearly transparent. Its growth is slow — it seldom is longer than
one foot, and this requires six or seven years to reach.
. The best Coral is found in the shallowest waters ; but it is found
as deep as 100 fathoms. Its ratio of growth is that of its depth.
Thus, it will increase in size a foot in eight years, in shallow water,
with a hot sun ; but it will take thirty years to reach that size at
100 fathoms. It varies in colour from yellow to a rich red. Dealers
recognise at least a dozen varieties. The hardest and most brilliant
in colour being the most prized. The same ground in the Coral
fisheries, as they are termed, is only dredged once in ten years, and
then in the rudest manner, by dragging a net over the bottom, and
thus getting what they can.

Still another Alcyonarian polyp demands our attention. It is that
which forms the beautiful " Organ Pipe" Coral, a figure of which is
seen at Fig. 161 (frontispiece). There is a peculiarity about this
form, which leads us to the next group, inasmuch as although it
is one of the Alcyonaria, with eight tentacles, yet the corallite is
secreted upon the "tissue" or " sclero-dermic " plan, while all the
others of the family form their skeletons upon the "foot" or
" sclero-basic " system.

We shall see that the first group of Corals, including all the reef
builders, secrete their skeletons on to former plan.

The " Organ Pipe " is a very inter-
esting Coral. Only the polyps in the
top platform, as seen in the figure, are
alive — as, in fact, I have before
noticed is the case in all Corals. The
polyp here has partially the power of
withdrawing itself into a calcareous
tube — hence the name of the genus —
Tubipora. They are of a beautiful
grass-green or violet colour, which
contrasts finely with the rich bright
crimson red of the Coral. Its mode
of reproduction is characteristic and

/v> • ,1 • • •, i •

poiyp-c c c c, edges of platforms cut sufficiently curious to merit a short

de8criP^on' Fi£' 172 represents an
enlarged figure of one of the tubes and
its polyp. Fig. 161 (frontispiece). The polyp (a) is shown partially

-

Pipe Coral. — a, polyp — 6, tube with live

THE LOWEE FORMS OP LIFE. 121

extended from the tube (b), which contains the rest of its body and
the germs of the future race of polyps, and it is able to protrude
from or draw into the tube by the contraction or relaxation of a pecu-
liar musculo-membranous structure. Now, where the polyps have
built up their tubes to say about the point c (Fig. 172), they simul-
taneously throw out a lateral process of lime-secreting coenosarc,
which processes, uniting together and becoming calcined, constitute
the platform (d, Fig. 172). Having effected this object, one or more of
the germs of each polyp become attached to the platform, grow up,
and, when they have arrived at the same height as their now dead
parents, they, like them, throw out lateral processes, form platforms,
and increase and multiply. Each stage, therefore, represents a
generation of polyps, the uppermost only being alive.

So much for the Alcyonarian polyps with their eight tentacles,
and, for the most part, " foot " or "base " secreted skeletons.

We will now turn to the Zoantharia, the polyp of which has five
or six tentacles, or multiples of those numbers, usually six, and whose
skeleton is built up upon the " tissue " or " sclero-dermic " system.

This division comprises the great number of Corals in the families
Madreporidse, Fungidse, Poritidee, Astraeidse, Milleporidae, &c., and
with which I shall make the reader acquainted by a short notice of
the figures in the frontispiece.

Another passage of the "Alcyonarian" to what has been well
termed the " Lamellarian" Corals, is effected by the clove-like form
known as Caryophyllia (Figs. 168-171, frontispiece).

In these Corals the single polyp lives at the extremity of the dead
stony mass, and is able to retract itself within the cup-like
extremity (Fig. 168). When the polyp dies, its successor forms a new
cup for itself over that of its dead parent, and then the calcareous
structure increases in length. Sometimes it is single, and at others
it assumes a dendritic or arborescent form (Fig. 171, frontispiece).
Sometimes the external surface is smooth (Fig. 168, frontispiece),
or pitted, as shown in the allied genus Pocillopores (Fig. 160, frontis-
piece).

In other instances, each cell is marked by a rim or circular inden-
tation, with longitudinal raised striae between each, as is seen in the
well-known form (Fig. 171, frontispiece). In all cases, however,
the single ^large sea-anemone, like polyp, lives alone at the end, and
its cup-like skeleton is divided into partitions of six, twelve, twenty-
four, &c., so that when the living polyp is removed a calcareous
lamellated structure of this kind is seen. In Fungia (Fig. 163,
frontispiece), each polyp enjoying a separate existence only forms
a single structure, the well known mushroom-shaped Corals of our
collections. Although I have represented in the figure a group of

122 POPULAR ILLUSTRATIONS OF

these Fuiigise, each corallum is separate. It is reproduced "by buds
or gemmules, each of which grows to a certain size, is then
detached, and becomes a free separate being, and forms its own
corallum, as " its fathers did before it." Now, were we to take a
number of Caryophilliae, and place them close together, we should
form a well-known Coral called Astrsea, as seen at Fig. 157 (frontis-
piece), with little or no stony substance or coanenchyma between the
cells ; but as some of the family like to live at a respectful distance
from each other, the ccenosarc secretes a ccenenchyma, as seen at
Fig. 167 (frontispiece).

Now it will be seen how easily and usefully our hard words step in.

Again, suppose that instead of having separate and distinct star-like
cups, as seen in Fig. 157 (frontispiece), each star was to become con-
fluent or join with its neighbour, we should then have the appearance
actually seen in the well-known "Brainstone Coral," of which a
figure of my specimen from Bermuda is seen at Fig. 152 (frontis-
piece). Of portable species this is among the largest, though they
are said to attain to six feet in diameter in the Bed Sea.

At Figs. 155, 169, 158, and 159 (frontispiece), we have examples
of some of the common species of Madrepore, in which the cells
are observed to stand out in prominent relief. In Figs. 166 and
156 (frontispiece), the cells are noticed to be, as it were, sunk in the
calcareous mass of Coral.

These last six species are among those most frequently found in
coral reefs, where we shall follow them in our next chapter.

CHAPTEE IX.
ON CORAL ISLANDS.

CORAL Islands and reefs are among the most interesting and remark-
able features on the surface of the earth, and in the natural history
of the world.

Take a map of the great Pacific Ocean, and mark out a space from
the island of Ducie, somewhere about 120° of W. longitude, to
the Pellew Islands, on the line which strikes 135° E. of Greenwich.
Your eye will run over a great group of islands occupying a
space 15° north and 30° south of the equator. The space
thus marked out is upwards of sixteen millions of square miles,
and, with the exception of part of New Holland and New Guinea,
all the islands over which your eye will pass have been formed

THE LOWEB FORMS OF LIFE. 123

into their present shape by the Coral polyp. This statement
is not invalidated but supported by the theory held by some, that
these islands are the high peaks of a vast continent gradually sinking
into the depths of the sea. If this be true, it involves a previous
sinking and a subsequent upheaving, for while all of them are more
or less surrounded by reefs, many are formed even to their tops
of dead Coral alone. That they are now sinking, I believe there is
no doubt ; and the beautiful and generally accepted theory of Mr.
Darwin, of the mode by which they were built up, is entirely based
upon this fact. The mind is startled when it contemplates the
immensity of time which has passed away since the Coral Islands
were first formed on the rising continent, and after its history in
time, the reefs and lagoons were formed by the same little polyps
as it gradually sank again into the unknown depths of the sea. I
shall allude to this subject again, but I may remark that no facts in
science are better known, and no generalisations more unanswerable
than those connected with the formation of coral structures in time-
and space.

In the meantime, let us examine the interesting question, so ably
treated by Mr. Darwin, of the modus operandi by which Coral Islands
and reefs are formed.

These islands and reefs are found in the great coral regions in
three or four different forms. First, we have islands in mid ocean,
with a lake in their centre; these are called "lagoon islands."
Secondly, we have islands formed entirely of dead Coral. Thirdly,
we have living coral reefs surrounding an island or bordering a.
continent, quite in shore, with a small space of still water between
the reef and the shore ; these are termed " fringing reefs." Then,
fourthly, these reefs are at a greater distance from land, leaving a.
large space of still water between them and the shore ; these are
termed " barrier reefs."

Now, before the publication of Mr. Darwin's work on the " Struc-
ture and Distribution of Coral Reefs," in 1842, we had no intelligible
theory to explain the formation of these reefs. I will briefly detail
this theory, referring those who wish for further information to ihe
admirable little book above mentioned.

The two essential facts upon which the theory is built up are,
first, that the whole of the land comprising what are known as the
South Pacific Islands and the continents bordering thereon, are at
the present time, and have been for ages past, gradually sinking ;
secondly, that the Coral polyps do not live at greater depths than
between twenty and thirty fathoms — Agassiz says from twelve to
fourteen fathoms.

Both of these positions have been ably argued by Mr. Darwin, and

124

POPULAR ILLUSTRATIONS OP

have been unchallenged for the last twenty-five years. Now upon
the above data, of which I will say more presently, Mr. Darwin
accounts for reef formations"thus :

Suppose a (Fig. 173) to be a section of a mountain portion of high
land, which is in a state of temporary quiescence, neither subsiding
nor rising, and that b is a coral reef, which has gradually been
formed by our friends the polyps. Now let us suppose, what is in
fact a frequent occurrence in the Pacific, that an active volcano
opens in the summit of a, as seen in the sectional diagram at
Fig. 174. Simultaneously with this active volcanic action, it accords

Fig. 173.

Fig. 174.

with experience that the mountain would begin to subside, and as it
did so the coral reef begun at b (Fig. 153), would continue to rise
as the polyps — which only live from twelve to thirty fathoms deep,
and never above low water — would keep adding to their wall just in
proportion as the land sank. Now the polyps for many reasons
thrive best outside the reef. They are, in fact, every now and then
destroyed between the inner boundary of the reef and the shore, and
the consequence is that the outside of the reef gets to be the highest,
and what is called a lagoon channel is formed between this front
and the shore, as seen in Fig. 174 (c). This lagoon is more or less

THE LOWER FORMS OF LIFE. 125

deep, but generally there is enough water to admit ships of all sizes.
This constitutes what is called a " fringing reef," the best examples
of which are found at the Salomon Isles, the New Hebrides, the
Friendly and Navigator's Islands in the Pacific, and at Sumatra,
Nicobar, Ceylon, Mauritius, Madagascar, and the African coast in
the Indian Ocean.

Now let us imagine this fringing reef to be a coral wall surround-
ing the island, and covered with living polyps to the bottom of the
lagoon channel on one side, and from twelve to twenty fathoms on
the other. And let us further suppose that a sudden sinking, of
say six feet, took place ; the immediate effect of this would be first
to kill all the polyps on the sea-side below thirty fathoms ; and
supposing the coral wall on the other hand to be built up six feet
.suddenly ; it is quite clear that, as the side of the mountain (a)

Fig. 175.

slopes considerably to the sea, by the above imaginary movement
the coral wall would be removed further from the shore, and the
lagoon channel would become wider. Now what I have supposed
might take place suddenly does actually occur slowly, and the result
of this subsidence of the land and the now languishing volcano is to
convert a "fringing" into what is known as a "barrier reef," as
seen in Fig. 175. The reef is still farther removed from the shore,
and the lagoon channel widens, as seen at Tahiti, Fidji, New
Caledonia, New Ireland, Oualan, Louisade, and the west coast of
New Guinea, and a large extent of coast from near Cape Sunday to
Torres Straits in the N.W. of New South Wales.

Barrier reefs are also found surrounding the Cormoro Islands in
the Indian Ocean and both sides of the shores of the Bed Sea, from
16° to 21° N. lat., occupying nearly the middle of the coasts of that

126 . POPULAR ILLUSTRATIONS OF

singular sea, while fringing reefs, as before mentioned, are found at
each end.

But in some instances, though rare, these "barrier reefs " appear
as circles of land covered with trees and vegetation. Mr. Darwin
explains this by the fact that floating masses of vegetable matter are
caught by, and entangled in, the uppermost ridge of the coral wall.
The Coral thus killed at the surface breaks up, and, mingling with
the extraneous matter, forms the basis of a soil in which the seeds
of the cocoa or other trees take root and grow, forming a wall of
vegetation round the island, as seen in that of Bolabola, of which
Mr. Darwin gives a sketch.

It is very rare, however, that the whole' of the upper part of the
reef, as in this instance, is converted into land. More frequently, as
would be supposed, and in accordance with the theory of their for-

Fig. 176.

mation, the land appears as a series of small islets, with smooth
water channels between them, through which ships pass from the
stormy sea into the quiet and lovely oasis within the reef.

Now let us imagine the process of sinking to go on as before,
until the top of the mountain has gone below the surface of the sea ;
and at the same time let us suppose the top of the coral wall to have
been, as in the case of the " barrier reef," partially converted into
land. We shall then have an "atoll," or "lagoon island," as shown
in the diagram 176, and actually seen in the Low and Caroline
Archipelagos, and in the majority of islands in the Pacific ; in the
Saya de Maeha, Cosmoledo, Chagos, Maldivas, Laccadives, and
Keeling Island in the Indian Ocean, and the Paraceles, &c., in the
China Sea.

THE LOWER FORMS OF LIFE. 127

Now remember that in the whole district of coral formation in
the Pacific, there are numerous active and many extinct volcanoes.
It is part of Mr. Darwin's theory that the mountain which has
sunk in the middle of the lagoon island was, when surrounded by
the " fringing reef," an active volcano, as shown in the diagram ;
and it is a strikingly confirmatory fact that the known active
volcanoes are all in islands or coastland which have "fringing reefs."
When its activity was exhausted it began to subside, as seen in the
diagrams.

It is quite true that Mr. Darwin's theory implies that the base of
the coral belt round the lagoon shall be at an enormous depth ; and
in many instances quoted by him this is actually the case. But
after a time the subsidence ceases. How long the submerged
mountain remains quiescent is not known ; but that a subsequent
upheaving takes place is proved by the fact that many of the
South Sea. Islands are entirely formed of Coral, from top to bottom.
Some of them are quite recent, and from 80ft. to 200ft. high, and
can only be accounted for by what I may term the indisputable fact
that they have been upheaved from the sea after the Coral polyp had
for ages been building up its reefs thereon. Great facts in confir-
mation of this sinking and submergence of large tracts of land and
mountains are well known to geologists. Marine strata are found
at the top of the Alps at 800ft. from the sea-level ; on the Pyrenees
at 10,000ft. ; on the Andes at 15,000ft. ; and on the great chain of
Himalayas at 18,000ft. Now, unless these mountains had been
raised up from the ocean, we must believe the ridiculous alternative
that the sea-level has subsided 18,000ft. !

On this subject, and the causes which operate in the rising and
sinking of the earth, and the proofs that both are in constant
operation, I must refer to " Principles of Geology," by Sir 0. Lyell,
where the subject is handled with great ability and research.

But there is still a very interesting question among the many
connected with coral reefs, about which I must offer a few remarks
— the rate of growth, and the known age of those now living, or
which have been formed during recent times.

On this subject we have most interesting data furnished by
Professor Agassiz, in the researches upon which he has founded a
beautiful series of deductions as to the formation of the peninsula
of Florida. By actual experiment he determined that in the period
of fourteen years the crust of Coral formed on the new foundation
of Fort Taylor, at Key West, and Fort Jefferson, on the Tortugas
Islands, did not exceed one inch. But as branching Corals only
occupy half the space they cover, Professor Agassiz considers that
the real rate of growth does not exceed half an inch in fourteen

128 POPULAR ILLUSTRATIONS OF

years ; although, to allow the most liberal scale in his calculations,
he sets it down as one foot in a century. I may here remark,
however, that Mr. Darwin states that a channel made with crowbars
through the reefs round Keeling Island, according to the authority
of Mr. Liesk, only ten years before, was at his visit so blocked up
with living Coral that ships could not enter. Mr. Darwin also
relates experiments conducted by Dr. Allen, of Forres, on the east
coast of Madagascar, who placed twenty Corals on a sand bank in
three feet of water (low tide), and in the July following each had
nearly reached the surface, and was quite immovable. Mr. Scutch-
bury also relates, in the West of England Journal, vol. i. p. 50,
that an oyster, only two years old, had attached to it a Coral, one of
the Agarica, which weighed 21b. 9oz. There is no doubt, however,
that the rate of growth varies with the species, and as Professor
Agassiz was well aware of the instance I have cited, as well as the
deduction of Mr. Dana from data supplied him by Sir J. G. Dalyell,
on the growth of Actinia — viz., that the polyp of the Coral
Madrepore increased three inches per annum, I presume he was
well satisfied with the correctness of his own experiments, and
of the deductions drawn from them. These deductions are the
following :

Beyond the mainland of the extremity of the peninsula of Florida
are a series of islands known as the "Keys," and of these "Key
West" is the most western. Outside these "Keys," and rising just
above and resting upon the Florida living reef, are a series of small
scattered islands. Now, mark that I have said, "living reef."
In fact, the Corals are alive from the surface of the water to the
depth of 60ft. Professor Agassiz places the limit of polyp life
much less deep than Mr. Darwin, as he says there is no proof that
the creature can live below twelve fathoms.

Calculating, therefore, that the Florida reef is sixty feet deep, and
that it has been built up at the rate of twelve inches in a century,
Professor Agassiz considers that this reef must have been six thou-
sand years in reaching its present height, and that the island out-
side the "Keys" must have taken this time to form.

On examining the "Keys" themselves, Professor Agassiz found
that they were nothing more than reefs which had been built up
before the outer reef began to form. Soundings gave the same
depth of 60ft., and the only difference between the inner reef and
the outer was that the crests of the former had been broken by the
action of the tides and storms. He then calculated that the age
of this old reef was 12,000 years, and he calls this the second item
in his calculation.

Now the "Keys" are separated from the shore by "mud flats,"

THE LOWER FORMS OF LIFE. 129

in which there is rarely more than a few fathoms of water, most of
which is uncovered at low tide. The shore itself is made up of
" bluffs " rarely more than ten feet high. North of the shore come
what are called Indian hunting grounds, " low, flat, marshy ponds,
hardly above the level of the sea ;" and still further up country are
another series of what are called "hummocks," which are "little
hilly tracts of land from five feet to ten feet above the level of the
sea, strangely arrayed in a row."

To make a long story short, Professor Agassiz discovered that
these bluffs of the shore, and the " hummocks " beyond them, were
severally the remains of coral reefs similar to that on which the
" Keys " are formed, and that which is just completed three miles
beyond it ! They have the same average thickness, and have been
built up by polyps specifically the same as those now living. There-
fore, says Professor Agassiz, we have evidence that " twenty-four
thousand years ago there was a sea washing the place where these
' hummocks ' are, and that no reef had then formed beneath them."
But still more. It appears that the space occupied by the four reefs
described covers only sixteen miles, but that similar concentrically
placed ".hummocks" exist as far as Lake Okeechobee, sixty miles in
the interior. "We shrink," says Professor Agassiz, "even from the
evidence that it has required 24,000 years to build this narrow strip
of land ; how shall we shrink from the assumption that hundreds of
thousands of years must have been required to build that prolonga-
tion of the peninsula of Florida, which is entirely made up of coral
reefs ? And yet what is that compared with the age of the world ?
It is to-day ! It is modern time ! It is the period called the present,
for it is a period within which the species of animals which now live
began to exist on the earth."

Such is the famous " Florida reef " induction — one of the latest
scientific investigations into the age of that world which was truly
"made in the beginning," and perfected for the success and main-
tenance of each successive race of beings, which we know full well
from the unerring records of geology have successively inhabited it.

I have not noticed the beauty of the scenery, nor the lovely
climate, nor the natural productions, nor the wild savages, nor the
still wilder storms, which are characteristic of the Coral Islands in the
Pacific Ocean. In Mr. Ellis' s interesting "Polynesian Eesearches "
much information on this subject will be found.

Of the other two divisions of the Actinozoa, viz., the Eugosa, the
species of which are all fossil, and the Ctenophora, which are all
oceanic, a good deal that is interesting might be said ; but their con-
sideration is of more importance to the purely-scientific man, and I
will, therefore, end here my "Popular Illustrations" of the Coelenterata.

130 POPULAR ILLUSTRATIONS OF THE LOWER FORMS OF LIFE.

The reader who wishes to know more about the sub-kingdoms
treated of in this volume will do well to consult the " Icones His-
tiologicse " of Kolliker ; Professor Greene's work on the Protozoa
and Coelenterata ; Professor Huxley's " Elements of Comparative
Anatomy ;" and Professor Owen's Lectures on the Invertebrata.

INDEX.

ANIMAL fibrine, 6

Azote, (J

Air cells, 12

Atmosphere, 14

Anther, 17

Albumen, 17

Annulosa, 19

Algae, 20, 38

Animalcule, 24

Allman, Professor, 27, 33

Acineta, stage of, Vorticellinae, 32

Acineta, germs of, 33

Amoeba, 34

Agassiz, Professor, 34, 127

Arcella, 38, 39

Azoic, 50

Acanthostaurus hastatus, 62

Acanthostaurus purpurascens, 62

Actinozoa, 70, 105

Antennularia antennina, Fig. of, 82

Anemone, sea, 109

Alcyonaria, 112

Astraea, 122

BALFOUR, Professor, 13

Balsam, 13

Bary, M., 24

Balbiani, 29

Bennett, Professor, 31

Bowerbank, Mr., 33

Beale, Mr., 33

Bulimina pupoides, Fig. of, 42

Bennett, Mr., 87

Brainstone Coral, 122

COTYLEDON, 4, 10
Caulicle, 5
Chlorine, 5
Carbon, 5
Caseine, 6
Cell, 8
Crystal, 11

Chlorophylle, 12

Carbonic acid, 2, 14

Carpenter, Dr., 15, 33, 34, 36, 41

Corolla, 17

Confervae, 20

Cyst-membrane, 24

Cystodia, 24

Cilia, 26

Cortical layer, 27

Cuticula, 27

Contractile chambers, 28

Contractile tissue, 31

Contractile filament, 31

Contractile vesicle, 32

Claparede and Lachmann, 36, 37

Chitine, 38

Cristellaria calcar, Fig. of, 42

Cornu ammonis, 43

Cambrian lower rocks, 48

Carboniferous rocks, 49

Coelenterata, 69

Corynidae, 77

Campanularia verticillata, Fig. of, 82

Calycophoridae, 84

Ccenosarc, 85

Chrysaora hysoscella, 97

Coral, 111

Corallite— corallum, 113-115

Ccenenchyma, 113

Corallium (genus), 119

Caryophyllia, 121

Coral islands, 122

Ctenophora, 129

DIASTASE, 6

Diatomaceae, 20

Dufour, Dr., 21

Difflugia, 38

D'Orbigny, 41

Dentalina legumen, Fig. of, 42

Discorbina globularis, Fig. of, 43

Devonian rock, -49

132

INDEX.

Diphyes dispar, Fig. of, 84
Darwin, Mr., 123

EMBRYO, 8

Endocarp, 3

Exogenous growth, 7

Endogenous growth, 7

Epiblema, 8

Endosmosis, 9^ .

Exosmosis, 9

Epidermis, 13- , -

Exhalation, .15. ,

Euplotes, 25; '

Ehrenberg, 28, 58

Entosolenia squamosa, Fig. of, 42

Eozoic, 50

Eoeoon Canadense, 51

Eocene, 55

Eucecryphalus Schultzei, Fig. of, 60

Ellis, Mr., 75

Eschscholtz, 88

Endoderm, 107

Ectoderm, 107

FLINT, 10

Filament, 17

Fission, 32

Foraminifera, 34-40, et passim

Fusulina, Fig. of, 53

Fishes in crust of earth, 53

Fungia, 121

Florida reef, 127

GERMINATION, 3

Growth, 4

Gluten, 5

Gliadine, 6

Goadby, Mr., 13

Granules, 17

Gregarina, 20, 22, 29

Greville, Dr., 31

Grant, Dr., 24, 64

Gullet, 31

Greene, the late Professor, 33

Gromia, 39

Globigerina bulloides, Fig. of, 42

HENSLOW, Professor, 3

Hydrogen, 4, 5

Heat, 4

Huxley, Professor, 33, 58

Hopkins, Mr., 49

Huron Lake, 51

Haughton, Professor, 55

Heliosphcsra inermis, Fig. of, 61

Hydrozoa, 69

Hydra, 71

Hermia glandulosa, Fig. of, 74 .

Hydrosoma, 78

Hydrothecae, 78

Hydrorhiza, 78

Hydraecium, 84

Hydrozoq,, reproduction of, 101

INTERNODE, 10

Instinct, 11

Iron, 5

Infusoria, 20

Icones Histiologicae, 21, 28

KOLLIKER, Professor, 21, 28

LIFE, 3

Lime, 5

Leaves, 12, 14

Laticiferous vessels, 14

Latex, 14

Loxodes, 25

Lieberkiihnia Wageneri, 37

Lagena vulgaris, Fig. of, 42

Lagena interrupta, Fig. of, 42

Lagynis Baltica, Fig. of, 46

Laurentian rocks, 49

Laomedea gelatinosa, Fig. of, 79

Lucernaridse, 99

Lucernaria campanulata, Fig. of, 99

MOLECULAR matter, 5

Magnesium, 5

Micropyle, 17

Mollusca, 19

Mycetozoa, 24

Motion of animalcules, 36

Miliola bicornis, Fig. of, 42

Miliola tenera, Fig. of, 43

Mackay, Mr., 48

Murchison, Sir Roderick, 48

Mammals in crust of earth, 53

Miocene, 55

Medusidse, 92

Medusa, Fig. of, 95

Madrepores, 122

NUCLEUS, 5, 28, 32
Nitrogen, 5
Node, 10
Nitric acid, 10
Nucleolus, 28, 32

INDEX.

133

Nodosaria radicula. Fig. of, 42
Nodosaria pyrula, Fig. of, 42
Nonionina Barleeana, Fig. of, 42
Nonionina Jeffreysii, Fig. of, 42
Nonionina elegans, Fig. of, 42
Neozoic, 50

Nummulites, 53, 55, 58
Nectosac, 84
Nectocalyx, 84

OXYGEN, 4, 5

Ovary, 17

Orbulina universa, Fig. of, 42

Orbitolites, Fig. of, 46

Oldhamia antiqua, 48

Ova, 108

Organ-Pipe Coral, 120

PROTOPHYTON, 1, 2

Protozoon, 1, 2, 19

Pericarp, 3

Pollen grain, 4

Plumule, 5, 10

Phosphorus, 5

Potassium, 5

Physical force, 11

Petiole, 12

Pigment cells, 13

Pistil, 17

Protozoa, 19

Pouchet, M., 24

Pasteur, M., 24

Pritchard, Dr., 25

Paramaecium, 25, 26, 29

Polygastrica, 26

Peristome, 31

Podophorya, 33

Proteus, 34

Podostoma, 36

Protoplasm, 36

Pseudopodia, 39, et passim

Polystomella crispa, Fig. of, 42

Permian strata, 49

Paleozoic, Upper and Lower, 49, 50

Pyramids, The, 55

Pliocene, 55

Physematium Mulleri, Fig. of, 63

Plumularia pinnata,.Fig. of, 82

Physophoridae, 86

Physalia Pelagica, 86

Physalia Caravella, 87

Physalia utriculus, 88, 90, Fig.

Pneumatophore, 89

Pneumatocyst, 91

Portuguese man-of-war, 91
Pelagia cyanea, Fig. of, 93
Phosphorescence of the sea, 99
Pennatula grisea, 118
Pocillopores, 121

RADICLE, 5., 8, 9

Reason, 11

Ranunculus aquaticus, Fig. of, 13

Respiration, 15

Radiata, 19

Radiolaria, 20, 58 - . • .

Rotatoria, 25 .

Rhizopoda, 33' " Y ,

Reticularia, 37

Rotalina concamerata, Fig. of, 42

Rotalina concamerata (jun.), Fig. of, 42

Rotalia, 53

Reptiles in crust of earth, 53

Rhizostoma Cuvieri, Fig. of, 94

Rugosa, 129

SEED, 4

Starch, 5, 20

Sodium, 5

Silica, 5 .

Sulphur, 5

Sugar (grape), 5, 17

Spongioles, 8, 14

Stem, 10

Silicic acid, 10

Stomata, 13

Stamens, 17

Stigma, 17

Style, 17

Sponges, 20

Stentor, 25

Sarcode, 26, 38

Stein, 29

Spirilina arenacea, Fig. of, 42

Schultze, Dr., 43

Silurian, upper and lower rocks, 49

Strabo on Nummulite, 55

Sponges, 63

Spiculae of Sponges, 66

Somatic cavity, 78

Sertularidae, 78

Sertularia polyzonias, Fig. of, 81

Somatocyst, 84

Sclero-basic, 111

Sclero-dermic, 111

TRAIL, Dr., 21

Trichocysts, 27

Textularia variabilis, Fig. of, 42

134

INDEX.

Textularia difformis, Fig. of, 42
Tchihatcheff, M., 55
Thalassieolla, 59

Thalassicolla pelagica, Fig. of, 60
Trembley, 73

Tubularia indivisa, Fig. of, 74
Thoa halecina, Fig. of, 81
Thuiaria thuia, Fig. of, 81

UVIGERINA PYGM^EA, Fig. of, 42

VITAL force, 2, 11, 17
Vegetable fibrine, 6
Vascular vessels, 13
Vertebrata, 19

Volvox globator, 20, 25, 26
Vorticella nebulifera, 25, 32
Vestibuhim, 31

WHEAT, 2
Watson, Bishop, 15
Wright, Dr., 33
Williamson, Dr., 41, 47
Wallich, Dr., 41
Willsia stellata, Fig. of, 96

YEAST, 6

ZOOPHYTES, 76
Zoantharia, 111

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