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THOUGHTS

ANIMALCULES;

OR, A GLIMPSE OF THE

INVISIBLE WORLD

REVEALED BY THE MICROSCOPE.

MAISASDM.METOALJ

5

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THOUGHTS

ANIMALCULES;

OR, A GLIMPSE OF THE

INVISIBLE WORLD

REVEALED BY THE MICROSCOPE.
BY

GIDEON ALGERNON MANTELL, ESQ., LL.D., F.R.S.,

AUTHOR OF THE "WONDERS OF GEOLOGY," ETC.

THE PHYSALIA PELAGICA, page

" In the leaves of every forest — in the flowers of every garden— in the waters
of every rivulet— there are worlds teeming with life, and numberless as are the
glories of the firmament."

Dr. Chalmers.

LONDON:
JOHN MURRAY, ALBEMARLE STREET.

1846.

LONDON :

W. JI'DOWALL, PKINXER, PEMBERTON ROW, GOUGH SQUARE.

THE MOST NOBLE

THE MAEQUESS OF NOETIIAMPTON,

PRESIDENT OF THE ROYAL SOCIETY,

!tC. &C. &C.,

THIS WORK IS MOST RESPECTFULLY INSCRIBED,

IN GRATEFUL ACKNOWLEDGMENT OF

lis Xortisl^ip's

ZEALOUS EXERTIONS FOR THE ADVANCEMENT OF SCIENCE AND ART,

AND AS A

TESTIMONY OF THE HIGH RESPECT AND REGARD OF

THE AUTHOR.

Chester Square, Pimlico ,
Februarii, 1846.

" To the Natural Philosopher there is no natural object that is unim-
portant or trifling : from the least of Nature's works he may learn the
greatest lessons."

Sir J. F. W. Herschel.

** The likeliest method of discovering Truth is by the observations
and experiments of many upon the same subject : and the most probable
way of engaging people in such investigations, is by rendering such obser-
vations and experiments easy, attractive, and intelligible."

Baker on the Microscope.

" I TELL thee that those living things,
To whom the fragile blade of grass,

That springeth in the mom

And perisheth ere noon,

Is an unbounded world —
I tell thee that those viewless beings,
WTiose mansion is the smallest particle
Of the impassive atmosphere.

Enjoy and live like man ;

And the minutest throb
That through their frame diffuses

The slightest, faintest motion.

Is fixed, and indispensable,

As the majestic laws
That rule yon rolling orbs."

Shelley.

PREFACE. U libraryUJ

The object of this Volume is to present a familiar
exposition of the nature and habits of some of the in-
visible beings which people our lakes and streams ; in
the hope, that by placing the most interesting pheno-
mena in a striking point of view, and describing them in
language divested as much as possible of scientific
terms, the subject may be rendered attractive to the
general reader, and some intelligent and inquiring minds
be led to the cultivation of a branch of natural know-
ledge, pre-eminently calculated to impart just and com-
prehensive views of the grandeur and harmony of the
Creation, and of the Infinite Wisdom and Beneficence
of its Divine Author ; and which, in every condition

X PREFACE.

and circumstance of life, will prove a never-failing
source of pleasure and instruction.
«
The Illustrations, with but few exceptions, are from
sketches, taken with a camera lucida while the objects
were under the microscope, either by my daughter or
myself; they have been reduced to the size required
for this work, by Mr. Mounsey, of Clapham Common,
for whose kind assistance I feel much indebted.

The account of the structure and habits of the Ani-
malcules, is based on the researches of M. Ehrenberg,
and other eminent observers; but almost all the facts
detailed, have come under, and are described from, my
own observations on specimens obtained from the pools,
and streams, around Clapham Common.

19, Chester Square, Pimlico,
London.

TABLE or CONTENTS.

Pa<,c
I. INTRODUCTORY— The Ideal Invisible World . 1

Milton — Byron — Bulwer — Locke.

II. The Invisible World revealed by the Microscope . 7
How to see— Captain Basil Hall— A group of Animalcules
— First glimpse of the In\risible World — Life in a di-
versity of forms.

III. The Hydra, or Fresh-water Polype . . . .12

Appearance of the Hydra— The Green Polype— The Com-
mon Polype— The Long-armed Polype— Polypes catch-
ing live prey — Tentacula of the Polype.

IV. The Divisibility of Vitality 18

Polypes cut to pieces — Each piece becomes a perfect
Animal— M. Trembley.

V. Cells the Essential Organs of Life . . . .22
The Polype a congeries of cells — Plants all cells — Perfect
plants consisting of one cell only — Animals formed of
cells — Animals consisting of one cell only — Analogy
not Identity — The First germ of Disease in the cells
— Practical suggestions — Inhalation in Consumption.

39684

XU TABLE OF CONTENTS.

VI. The Infusoria, or Fresh-water Animalcules . . 28
Ehrenberg's discoveries — Animals in Vegetable Infusions —
The Cilia, or vibratile organs.

VII. The POLYGASTRIA 32

Animals only -g-^^ of a line in diameter — Mechanism of
the Cilia — Cilia of the Rotifer.

VIII. The Monads 36

Monads the minutest animals revealed by the Microscope
— Masses of slime composed of countless myriads of
Monads — The Monas crepusculum— The Chlamido-
monas — Increase by self-division — The Gonium— its
mode of increase — The Volvox globator — Monad of
the Volvox — Globe within globe— The Vibrio, or
Trembler.

IX. The Vorticellina, or Bell-shaped Animalcules . . 42

Animals grouped together like plants — The Stentors — The
Bell-shaped Animalcules— Animalcules fed with car-
mine—Stomachs of the Poly gastria— Increase of the
Vorticellse by self-division — The Arborescent, or Tree
Vorticellse — Physiological summary.

X. The RoTiFERA, or Rotating Animalcules . . . .52
Structure of the Rotifera— The rotators, or wheels— The
jaws and teeth of the Rotifera — Respiratory Organs —
Nei^ves and eyes.

XI. The Floscularia, or Flower-shaped Animalcules . 58
The Limnias, or Water Nymph — The Melicerta, or Honey
Floscularia — Sheath of the young coloured by car-
mine—The Elegant Floscularia— The Horned Flos-
cularia.

TABLE OF CONTENTS. Xlll

Page
XII . The Stephanoceros, or Crowned Wheel-animalcule . . 63
The appearance of the Stephanoceros — its ciliated tentacula
— its transparent, flexible, tubular case — The Stephano-
ceros Ehrenbergi — development of the young in the
Stephanoceros — Embryo in the egg — Liberation of the
young from the Egg, and from the sheath of the parent
— Various stages of growth.

XIII. The Rotifer, or Wheel-animalcule 71

The Rotifer vulgaris— its internal structure— the Wheels, or
rotatory organs— the Eggs — rate of increase — its dis-
tribution— its resuscitation.

XIV. Animalcules with durable cases, or shells . . . .79

The Brachionus, or Spine-bearing Animalcule — The Pitcher-
shaped Brachionus — its jaws and teeth — Baker's Bra-
chionus— Strata composed of cases of Infusoria.

XV. Reflections . . . . 82

XVI. General Remarks — Conclusion . . . . '85
The Infusoria — Influence of Temperature— Animalcules in
vegetable infusions — The ova and germs of Animal-
cules every where — Animal structures almost fluid —
The Medusae — The Power of Vitality — Fiual purposes
— Animalcular origin of many Epidemic diseases —
The moral Influence of natural knowledge.

Appendix 95

Miscellaneous Notes . . " 109

Description of the Plates 113

Index . . . . . .139

LIST OF THE ILLUSTEATIONS.

Page

Plate I. Illustration of the Hydrae, or Fresh- water Polypes . .114

II. Monads and Stentors . . . . . . .116

Vibrio. Gonium. Chlamidomonas. Monas termo.
Volvox globator. Stentor.

III. The Vorticellae, or Bell-shaped Animalcules . . .118

IV. The Limnias, or Water-Nymph 120

V. The Mehcerta, or Honey Floscularia . . . .122

VI. The Floscularia, or Flower-shaped Animalcule . . .124

VII, The Floscularia ornata, or Elegant Floscularia . . . 126

VIII. The Floscularia proboscidea, or Horned Floscularia . . 128

IX. The Stephanoceros, or Crowned Animalcule . . . 130

X. The Stephanoceros Ehrenbergi ; shewing the development

the ova 132

XI. Development of the young Stephanoceros . . . .134
XII. The Rotifer, or Wheel-animalcule ; and the Brachionus, or

Spine-bearing Animalcule 136

LIGNOGRAPHS.

1. Rotifer vulgaris; the upper part of the body, and the wheels

or rotators, highly magnified 35

2. A single Annulated Vorticella, (Vorticella convallaria), highly

magnified 47

XVI

LIST OF THE ILLUSTRATIONS.

3. The Tree Vorticella, or Carchesium .

4. Jaws and teeth of the Notommata

5. Fig. 1, Jaws and teeth of the Floscularia
Fig. 2, Jaws and teeth of the Brachionus

6. Jaws and teeth of the Rotifer vulgaris

7. Jaws and teeth of the Stephanoceros .

Page
49
54
55
55
56
56

THOUGHTS ON ANIMALCULES,

" The majesty of God appears no less in smaU things than in great;
and, as it exceedeth human sense in the immensity of the Universe, so
also doth it in the smallness of the parts thereof." — Hobbes.

I.

INTRODUCTORY.— THE IDEAL INVISIBLE WORLD.

In every country and in every age, a belief in the
existence of beings invisible to mortal eye has more
or less generally prevailed; and the air, the earth, and
the waters have been peopled by ideal forms, invested
with natures and attributes partaking of the charac-
ters of the minds from which thej emanated. Hence
sprang the Gnome of the mine and the cavern; the
Goule of the charnel-house and the tomb ; the beauti-

2 THOUGHTS ON ANIMALCULES.

ful mythology of Fairy-land, and the dreamy creations
of the ancient philosophers, who, like the Chaldeans,

watch'd the stars.

Till they had peopled them with beings bright
As their own beams.

Childe Harold.

A sublimer creed succeeded, and is shadowed forth
in the following noble lines of our divine poet : —

Nor think, though Man were none,

That heav'n would want spectators, God want praise.
Millions of spiritual beings walk the earth,
Unseen, both when we wake and when we sleep !

Paradise Lost, Book IV.

This faith in the existence of supernatural beings,
whose presence is but rarely made manifest to mortals,
appears to be innate in the human mind. Its creations
have varied with the progress of civilisation and refine-
ment, and the inhabitants of the unseen world been
invested with higher attributes and subtler natures;
but the beautiful superstition, though modified, still
retains its influence, and even yet throws its spell over
the imaginings of the poet, and the speculations of the
philosopher and the sage.

Who, in the bloom and freshness of youth, ere the

THE IDEAL INVISIBLE WORLD. 3

best feelings of the heart are blunted and perverted by
the turmoil and cares of the world, has not felt an in-
tense desire to remove the veil that shrouds from our
senses the invisible creation, and hold converse with
being's of a hiMier order than ourselves ? Who has not
experienced that yearning after the " Desert," and the
" ministering Spirit," so finely expressed by Lord Byron,
in a stanza of inimitable beauty and pathos ?

Oh ! that the Desert were my dwelling-place,
With one fair Spirit for my minister,
That I might all forget the human race,
And, hating no one, love but only her !
Ye Elements ! — in whose ennobling stir
I feel myself exalted — Can ye not
Accord me such a being ? Do I err
In deeming such inhabit many a spot ?
Though with them to convei se can rarely be our lot.

Childe Harold, Canto IV.

And in after years, in those hours when, escaping
from the vexations and excitements of active life, we
fly for solace to the realms of fiction, and, giving our-
selves up to the magic page of Shakespear, of Scott,
or of Bulwer, forget for a wliile our anxieties and our
sorrows, the visions of our early days will sometimes
steal over us, we resign ourselves to the illusion, and
once more the streams, the forests, and the air teem

b2

4 THOUGHTS ON ANIMALCULES.

with the spirits of the invisible world; the hallowed be-
hef of our boyhood,

Still lingering haunts the greenest spot
In memory's waste.

In such a frame of mind we are unwilling to re-
nounce our early faith, and are ready to exclaim, in the
eloquent language of Sir Edward Bulwer — " Is there
indeed no truth in our fictions of the unseen world?
Are there not yet bright lingerers by the forest and the
streams ? Do the moon and the soft stars look out on
no delicate and winged forms bathing in their light?
Are the fairies and the invisible hosts but the children
of our dreams, and not their inspiration? Are the
chimeras of the passions the sole spirits of the uni-
verse? No! the trust in brighter shapes and fairer
natures than the world knows of comes clinging to my
heart!*"

But let us pass from the glowing fictions of the poets,
to the calm reasoning and cautious inductions of the
philosopher : " That there should be more species of
intelhgent creatures above us, than there are of sensible
and material beings below us, is probable to me from

; * " The Pilgrims of the Rhine/' by Sir E. Bulwer Lytton, Bart.

THE IDEAL INVISIBLE WORLD. 5

hence, that in all the visible and corporeal world we
perceive no interruptions, no chasms. Down to the
lowest and most inorganic parts of matter, we find
everywhere that the several species are linked together,
and differ but in insensible degrees. And we have,
therefore, reason to think that it is in accordance with
the magnificent harmony of the universe, and the de-
sign and infinite goodness of its great Author, that the
species of creatures should also by gentle degrees ascend
upwards from us towards Infinite Perfection, as we see
they gradually do from us downwards. We have,
therefore, reason to conclude that there are far more
species of creatures above us than there are beneath us ;
man being so much more remote from the Infinite Per-
fection of God, than from the very lowest state of
being, or that which approaches nearest to nothing*."

That our planet may at the present moment be the
abode of numberless invisible intelligences of a higher
nature than man — as it was, in the ages antecedent to
the creation of the human race, of thousands of beings
now extinct — neither religion nor philosophy requires
us to disbelieve f. However this be, all attempts to

* Locke's Essays.

t '' The Scriptures assure us, that beings raised as far above the limited
powers of man, as man is raised above the insect tribes, actually exist." —
Dr. Dick's '* Philosophy of a Fut'.ire State," 2nd edition, p. 291.

0 THOUGHTS ON ANIMALCULES.

commune with these spiritual existences, and render
them manifest to our senses, have hitherto been in vain.
Even the familiar of the Wizard, and the attendant
spirit of the Magician (the reality of which, but little
more than a century since, it was deemed heretical to
deny), have passed into airy nothing, with the ignorance
and superstition that gave them birth.

THE INVISIBLE WORLD REVEALEDo

11.

THE INVISIBLE V^ORLD REVEALED BY THE
MICROSCOPE.

But a fact not less startling than would be the
realisation of the imaginings of Shakespear and of Mil-
ton, or of the speculations of Locke and of Bacon,
admits of easy demonstration, namely, that the air, the
earth, and the waters teem with numberless myriads of
creatures, which are as unknown and as unapproachable
to the great mass of mankind, as are the inliabitants of
another planet. It may, indeed, be questioned, whether,
if the telescope could bring within the reach of our
observation the living things that dwell in the worlds
around us, life would be there displayed in forms more
diversified, in organisms more marvellous, under con-
ditions more unhke those in wliich animal existence
appears to our unassisted senses, than may be dis-
covered " in the leaves of every forest, in the flowers of
every garden, in the waters oi every rivulet," by that
noblest instrument of natural philosophy, the Micro-
scope.

8 ' THOUGHTS ON ANIMALCULES.

To an intelligent person, who has previously obtained
a general idea of the nature of the objects about to be
submitted to his inspection, a group of living animal-
cules, seen under a powerful microscope for the first
time, presents a scene of extraordinary interest, and
never fails to call forth an expression of amazement and
admiration*. This statement admits of an easy illus-

* It is so absolutely necessary that the observer should previously have
a general notion of the objects to be inspected, that I solicit the reader's
attention to the following pertinent remarks of Captain Basil Hall. — " I
have known many observant and quick -sighted men fail to perceive a
double star in the heavens, while to others more practised, though using
the same telescope, both objects were clearly defined. The secret often
lies in knowing exactly what to look for, and thence learning how to ad-
just, not merely the focus of the eye, but what may be termed the focus
of the judgment, so as to be able to pitch the understanding into such a
key that the information may be understood when it comes. I remember
being present once at the Geological Society, when a bottle was produced,
which was said to contain certain zoophytes. It was handed round, in
the first instance, among the initiated on the foremost benches, who com-
mented freely with one another on the forms of the animals in the fluid :
but, when it came to our hands, we could discover nothing in the bottle
but the most limpid fluid, — without any trace, so far as our optics could
make out, of animals dead or alive, the whole appearing absolutely trans-
parent. The surprise of the ignorant at seeing nothing was only equal
to that of the learned who saw so much to admire ; nor was it till we were
specifically instructed what we were to look for, and the shape, size, and
general aspect of the zoophytes pointed out, that our understandings
began to co-operate with our eyesight in peopling the fluid, which, up to
that moment, had seemed perfectly uninhabited. The wonder then was,
how we could possibly have omitted seeing objects now so palpable."

THE INVISIBLE WORLD REVEALED. 9

tration; for example — from some water containing
aquatic plants, collected from a pond on Clapham Com-
mon, I select a small twig, to which are attached a few
delicate flakes, apparently of slime or jelly; some
minute fibres, standing erect here and there on the
twig, are also dimly visible to the naked eye. This twig,
with a drop or two of the water, we will put between
two thin plates of glass, and place under the field of
view of a microscope, having lenses that magnify the
image of an object 200 times in linear dimensions*.
Upon looking through the instrument, we find the fluid
swarming with animals of various shapes and magnitudes.
Some are darting through the water with great rapidity,
while others are pursuing and devouring creatures more
infinitesimal than themselves. Many are attached to the
twig by long delicate threads, (the Vorticellce, pi. iii,
fig. 3); several have their bodies inclosed in a trans-
parent tube, from one end of which the animal partly
protrudes and then recedes, (the Floscularice, pi. vii);
while numbers are covered by an elegant shell or case,
(the Brachionus, pi. xii, figs. 1, 2). The minutest
kinds, (the Monads, pi. ii, figs. 1, 6), many of wliich
are so small that millions might be contained in a single

"Patchwork," by Captain Basil Hall, Vol. iii, p. 13. — London, J^-r'j:^--~>^
Moxon, Dover Street, 1841. /~C\<^-^~^ L y

fOD/^ -^®^ ^\f^^^
LuiLIBRARYJ^J

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* This is equal to 40,000 times in superficial dimension.

10 THOUGHTS ON ANIMALCULES.

drop of water, appear like mere animated globules, free,
single, and of various colours, sporting about in every
direction. Numerous species resemble pearly or opaline
cups or vases, fringed round the margin with delicate
fibres that are in constant oscillation, (the Vorticellcs,
pi. in). Some of these are attached by spiral tendrils ;
others are united by a slender stem to one common
trunks appearing like a bunch of hare-beUs, (the Car-
chesium, pi. in, fig. 1); others are of a globular form,
and grouped together in a definite pattern on a tabular
or spherical membranous case for a certain period of
their existence, and ultimately become detached and
locomotive, (the Gonium and Volvox, pi. ii, figs. 2, 9) ;
while many are permanently clustered together, and
die if separated from the parent mass. No organs of
progressive motion, similar to those of beasts, birds, or
fishes, are observable in these beings ; yet they traverse
the water with rapidity, without the aid of limbs or
fins; and, though many species are destitute of eyes,
yet all possess an accurate perception of the presence of
other bodies, and pursue and capture their prey with
unerring purpose.

The study of the nature and economy of these mar-
vellous creatures must, however, be regarded not merely
as an amusement for the gratification of an intelligent
curiosity, but as a branch of natural knowledge fraught

THE INVISIBLE WORLD REVEALED. 11

with the highest interest ; since, by a profound investi-
gation of the modifications of structure and functions
exhibited in these minute organisms, much light has
already been shed upon some of the most obscure phe-
nomena in the physiology of man. And there are still
certain parts of the human frame, whose intimate struc-
ture and especial office are unknown, and wiU probably
remain a mystery, unless revealed by observations on
these minute forms of being ; in which, from the trans-
parency of their integmnents, and the distinctness of
their internal organs, the most important vital opera-
tions are submitted to our scrutiny.

In contemplating the swarms of living atoms under
the microscope, the idea that most strongly impresses
the mind, after the first sensation of surprise has sub-
sided, is the infinitesimal minuteness, and simple condi-
tion of many of the structures, in which that marvellous
principle, life, is enshrined. We have been accustomed
to associate the presence of vitality with bodies possessing
various complicated organs for the elaboration and main-
tenance of the energies of existence ; but here we see
perfect and distinct creatures in the condition of single
globules and cells, that live, and move, and have their
being, and increase in numbers with a rapidity so prodi-
gious, and in modes so peculiar, as to startle all our
preconceived notions of animal organisation.

12 THOUGHTS ON ANI3IALCX^LES.

III.

THE HYDRA, OR FRESH-WATER POLYPE.
Plate I.

With the view of facilitating the comprehension of the
vital phenomena that will come under our notice, when
we enter in detail on the natural history of the animal-
cules selected as the subjects of these illustrations, I
would first direct attention to the objects contained in
this phial of water: they are living fresh-water polypes,
or HydrcB, (pi. i.); animals that present considerable
analogy in their structure to many of the simplest forms
revealed by the microscope; and, being relatively of con-
siderable size, and abundant in ponds and rivulets,
they afford a convenient illustration of some of the most
interesting physiological problems involved in the study
of this division of animated nature.

The Hydra* is common in almost every pool of fresh
water, and is generally found attached to the stems or
leaves of aquatic plants, or to twigs and branches that

* Hydra: so named from the fabled water-serpent, whose numerous
heads were reproduced as often as cut off.

THE HYDR^, OR POLYPES. 13

have fallen into the water. When in an expanded state
it resembles a slender, semi-transparent cylinder or tube,
about the size of a hog's bristle, from one-quarter to
three-quarters of an inch in length, and which is con-
stricted at the end that is attached to the plant. At the
free extremity there is an aperture, or mouth, surrounded
by several long, delicate, tubular arms, or tentacula, vary-
ing in number in the different species from six to ten.
The polype, when contracted, appears hke a little ball
of jelly, scarcely one-tenth of an inch in diameter; and
the arms are then shrunk into small papillae, or eminences,
forming a zone round the upper part of the body, (pi. i,
fig. 5).

There are four or five British species ; the three com-
monly met with around London are figured in Plate i.

I. The Green Polype, {Hydra viridis, pi, i, figs. 1,
9). — This species is of a delicate green colour. Its body
is cylindrical, but gradually becomes more slender to-
wards the lower extremity. It has from six to ten
tentacula, or arms, which are not so long as the body.

Fig. 1, represents three individuals attached to a
twig, as seen expanded in a phial of water.

Fig. 9, shews a polype in four different positions, to
illustrate its mode of progression. The polype per-
forms locomotion by extending its arms and attaching

14 THOUGHTS ON ANIMALCULES.

them to a fixed point, and then drawing its body to the
same spot; the various attitudes it assumes in these
movements are shewn in the figures : a denotes the base,
or pedicle; and h, the head, or mouth.

The locomotive actions of the hydra are slow, but
may readily be observed if that part of the glass to
which the animal is attached be turned from the win-
dow ; for the polypes, though destitute of any visual
organs, always move towards the light, and quickly
begin to shift from the dark side of the vessel, standing
at first erect upon the pedicle, and throwing their arms
forwards and fixing them, thus bending the body arch-
wise, and at length drawing the tail towards the head,
as shewn in pi. i, fig. 9.

II. The Common Polype, [Hydra vulgaris, pi. i,
figs. 2, 4, 8). — The body is of a cylindrical form, and
of an orange-brown colour. It has from seven to twelve
arms, which are a little longer than the body.

Fig. 2, a polype contracted.

Fig. 5, a front view of an individual still more col-
lapsed.

Fig. 4, a polype, with two young ones, of different
ages, shooting out from the body.

III. The Long-armed Polype, {Hydra fasca, pi. i.

THE HYDRyE, OR POLYPES. 15

figs. 3, 65 7). — The body is of a brownish colour, and its
lower half much more slender than the upper part. The
arms are, in general, from six to eight in number, and
several times longer than the body.

Fig. 3, an individual with the arms fully extended in
quest of prey. A red worm (c), and a small water in-
sect (d), are seen captured by the tentacula.

Fig. 6, a polype bending its body, and throwing about
its arms in an undulating manner in search of food.

Fig. 7, a red worm partly drawn into the stomach of
a polype, being too large to be swallowed entire.

Fig. 8, a vertical or longitudinal section of a polype,
highly magnified, to shew the internal structure: e, the
cellular tissue, which forms the constituent substance of
the entire animal; y^ the tubular arms; g, the inner sur-
face of the digestive sac.

The Hydra, when taken out of the water, shrinks into
a small round mass, which, examined under the micro-
scope, is seen to be composed of cells, and of greenish or
reddish brown granules, loosely connected by a glairy
mucus. The cells are condensed on the external surface,
so as to constitute a double layer of integument; but
the lining of the cavity of the body is made up of cells
that are transversely elongated, and forms a surface which
is covered with exceedingly minute eminences, termed
villi, from the resemblance to the pile of velvet.

16 THOUGHTS ON ANIMALCULES.

If a piece of stem or leaf to which some polypes
are attached, is put into a small clear phial filled with
water, and placed on the cell of a window where the
objects can be conveniently examined, the little animals
will in a short time extend and spread out their arms
in quest of prey ; and, if a small lively worm is dropped
into the water, they quickly rouse into full activity,
while the worm, apparently conscious of its danger,
throws itself into violent contortions. One of the
polypes then stretches out its arms, perhaps to the
length of several inches, till they become as attenuated
as a spider's web, and suddenly seizes and entangles its
prey, (see pi. i, fig. 3, c), which in a moment, as if
paralysed by an electric shock, ceases its struggles, and
is then slowly drawn to the mouth, and swallowed, (see
pL I, fig. 7), The body of the hydra now becomes dis-
tended; digestion rapidly takes place, as is shewn by the
difiusion of the red colour of the worm tlirough the sub-
stance of the polype; and, after some hours, the indigest-
ible portions are rejected by the mouth.

In watching this experiment, the extraordinary pow-
ers possessed by the tentacula — those apparently mere
attenuated threads — cannot fail to arrest attention.
These instruments, when stretched to the utmost, {see pi.
I, fig. 3), are as fine as the finest cobweb; but a high
magnifying power shews them to be tubular, and filled

THE HYDR.E, OR POLYPES. 17

with fluid, their substance being a congeries of cells and
granules like the rest of the body, of which, indeed, they
are only prolongations. The arms have rows of minute
eminences or nodules spirally arranged, which can be
exserted and drawn in at pleasure. Tliis structure may
account for the security with which the living prey is
retained in spite of its struggles, but will in nowise
enable us to explain how instruments so dehcate can
resist the violent contortions of worms and other rela-
tively powerful animals. I have seen a polype seize
two large worms at the same instant; and, to reach them,
the arms were extended to such a degree of tenuity, as
scarcely to be perceptible without the aid of a lens ; and
the worms, though very lively, and struggling violently,
were unable to break asunder these delicate instruments
and escape, but in an instant were struck motionless.
This phenomenon strikingly resembles the effect pro-
duced by the Gymnotus, or electrical eel ; and it is not
improbable, that the Hydra, like that fish, kills its prey
by an electric shock.

18 THOUGHTS ON ANIMALCULES.

IV.

THE DIVISIBILITY OF VITALITY.

The most extraordinary vital endowment possessed
by the Fresh-Avater Polype, is that of the reproduction
of lost parts to an almost unlimited extent, even to the
formation of several perfect individuals from the divided
parts of a single Hydra. If a polype is cut across trans-
versely, the upper part with the arms quickly produces
a new body and tail ; and the lower portion as rapidl}^
throws out another body and arms. If the body is slit
down longitudinally, and left united at the base, each
portion grows into an entire polype, the requisite num-
ber of arms shoot out, and two perfect animals attached
to one common base are produced ; and, if the division
be complete, two free hydra3 are the result. One polype
was cut into ten pieces, and each piece grew into an entire
animal. If a polype is turned inside out, a transmuta-
tion not less wonderful, physiologically considered, than
the above process takes place : the original outer surface
performs the function of digestion, while the former
linino; of the stomach becomes the external inteo;ument

THE DIVISIBILITY OF VITALITY. 19

or skin; the animal apparently suffering no incon-
venience from the operation.

The discovery of this marvellous power of reproduction
in the Hydra, was made about a century since by a M.
Trembley, then residing at the Hague, who, in the
course of some researches for small aquatic insects, was
struck with the apparently spontaneous movements of
some delicate fibres which he supposed were the roots or
tendiils of plants growing in the water. Finding that
these fibres contracted when touched, and extended them-
selves again if left undisturbed, he at first surmised that
their motions were analogous to those of the sensitive
plant ; for the bodies in question were so unlike anything
at that period recognised as belonging to the animal king-
dom, that their true character was not suspected. Re-
peated observations, however, convinced M. Trembley
that these movements were much more active than any
apparent in vegetables, and he was greatly perplexed as
to their real nature ; he, therefore, resolved to submit the
supposed plants to an experiment, which he naturally
thought must be conclusive. Accordingly he selected
several specimens detached from the stem of a plant, and
cut them to pieces, leaving them, after the subdivision,
in a glass with water, and then patiently and cautiously
watched the result. To his utter astonishment, each
portion preserved its vitality, and grew up into a perfect

c2

20 THOUGHTS ON ANIMALCULES.

whole. Their vegetable nature was, therefore, at first,
deemed unquestionable ; but M. Trembley having no-
ticed the spontaneous motions of the mutilated polypes as
they advanced to perfection, with great sagacity inferred
that they were true animals, possessing a structure which,
like that of certain plants, admitted of subdivision, with-
out destroying its vitality or powers of reparation.

It may easily be conceived how great was the aston-
ishment excited by this discovery; and its announce-
ment was received with hesitation by some, and ridi-
culed by others. Such, however, was the curiosity
awakened among the naturalists of this country, that
the then President of the Royal Society, Martin Folkes,
repeated the experiment upon some polypes sent to him
by M. Trembley from Holland ; for, although the ponds
and rivulets around London abounded in these animals,
and their existence had been made known forty years
previously by the celebrated Leeuwenhoek, the fact
appears to have been entirely overlooked or forgotten.
Subsequently, Mr. Henry Baker, an eminent micro-
scopical observer, verified the statements of M. Trem-
bley in every essential particular, and published the
result of his experiments in an interesting volume,
wdiich is still the best English w^ork on the subject*.

* ** An Attempt towards the Natural History of the Polype. By Henry
Baker, F.R.S., London, 1743." One volume, 8vo, with numerous ligno-

THE DIVISIBILITY OF VITALITY. 21

graphs. Such of my readers as indulge in the kixury of a hunt over the
old book-stalls may be so fortunate as to meet with a copy of this work.
But those who feel particularly interested in the subject, should endeavour
to procure M.Trembley's 4to, intitled ^* Memoires pour servir a VHistoire
d^un Genre de Polypes d'Eau douce. Par A. Trembler/, de la Societe
Roy ale. A Leide^ 1744." This volume is one of the most delightful
contributions to natural knowledge ever published : its narrative is en-
livened by so refreshing an enthusiasm, its descriptions are so graphic,
and the illustrations so faithful, and in the highest excellence of art, (being
engraved by the celebrated Lyonet), that it is worthy of a place in the
best libraries. I obtained a copy some years since through M. Bailliere,
the foreign bookseller. Regent Street, London.

22 THOUGHTS ON ANIMALCULES.

CELLS, THE ESSENTIAL ORGANS OF LIFE.

The interpretation of these phenomena is to be found
in the peculiar organisation of the Hydra: its entire
structure being nothing more than an aggregation of
cells. A vertical section of a polype (see pi. i, fig. 8),
shews the internal cavity or digestive sac, the relative
tliickness of the substance of the body, and the manner
in which the arms are formed by a prolongation of the
upper part into hollow processes. The entire animal
consists, in fact, of a simple cavity formed of a congeries
of cells, for the reception and assimilation of food. The
cells lining the stomach select and absorb the nutritious
particles, and the tube then spontaneously contracts, and
casts out the residue of digestion. .The organisation of
the polype is, therefore, analogous to that of the simplest
condition of the vegetable kingdom, the Cellulosm ; for,
even in the large Fuci, or sea-weeds, the whole fabric
consists of cells. The fresh-water Confervce are merely
jointed films composed of cells, which contain granules
or lesser cells. A cell bursts, the granules escape, float

CELLS, THE ESSENTIAL ORGANS OF LIFE. 23

in the water till they become fixed to some other body,
and then reproduce cells, which are aggregated after
the same pattern as in the parent plant. The common
mould or mustiness is a cluster of plants formed of cells
only : and there are some vegetables in which the entire
plant consists of but one isolated cell; such are the yeast
fungus {Torula cerevisice), and the red snow (Leparia
nivalis). In these examples we have proof that all those
functions in which the organic life of vegetables essen-
tially consists, namely, absorption, assimilation, the fixa-
tion of carbon from the atmosphere, respiration, exhala-
tion, secretion, and reproduction, are effected by one
simple cell. Even in the highest and most complicated
orders of vegetables, in which there is a variety of or-
gans adapted for the performance of different offices,
these functions are performed by the agency of cells,
which obtain materials of formation and support from
the ordinary chemical agents around them. Thus, an
aggregation of simple cells forms the cellular tissue ; a
fusion or blending of several cells produces the vessels, and
so forth ; and by cells are elaborated the gum, resin, oil,
starch, gluten, &c. ; and, by cells specially endowed, are
secreted the narcotic of the poppy, the deadly poison of
the nightshade, and the stimulant aromatic of the clove.
In like manner, in animal structures, all the various pro-
cesses of vitality are performed by cells or globules.

24 THOUGHTS ON ANIMALCULES.

varying in size from infinite minuteness to forms visible
to tlie unassisted eye. In fine, a minute globular cell
is typical of the common germ from whicb all organic
fabrics proceed. All animals and plants may justly be
regarded as definite aggregations of cells, endowed with
specific properties in the different types, and subjected to
a never varying law of development*. And in animals,
as well as in plants, there are certain kinds in which the

* Although it is now a received physiological axiom, that cells are the
elementary basis, the ultimate limit, of all animal and vegetable structures,
and that the varied functions in which organic life essentially consists are
performed by the agency of cells, which are not distinguishable from each
other by any well marked characters, there is not the slightest ground for
assuming any identity between the primary cells even of the simplest
species of animals or vegetables, much less between those of more com-
plicated organisation. The single cell, which embodies vitality in the
yeast fungus or in the monad, is governed by the same immutable or-
ganic laws which preside over the complicated machinery of Man and the
other vertebrata ; and the smgle cell, which is the embryotic condition of
the Mammal, has no more relation to the single cell, which is the per-
manent condition of the Monad, than has the perfect animal into which
the mammalian cell ultimately becomes developed. The cell that forms
the germ of each species of organism is endowed with special properties,
which can result in nothing but the fabrication of that particular species.
The serious error which pervades the theory advanced in the work inti-
tled " The Vestiges of the Natural History of the Creation" has arisen
from its author having, in many instances, assumed analogy to be a proof
of identity. There is an analogy between the human embryo and the
monad of the Volvox, in that each consists of simple cells ; but there is no
more identity between the human and the polygastrian cells, than be-
tween the perfect man and the mature animalcule.

CELLS, THE ESSENTIAL ORGANS OF LIFE. 25

entire animal consists of but one single cell, [the Mo-
nads)', and others, in which each individual is but a
cluster of such cells arranged in a definite manner.
These mere aggregations of simple cells perform all the
functions of animal life, namely, the maintenance of a
particular form for a certain duration of time, the ela-
boration of materials of support from food, locomotion,
and the continuation of the species; hence, these ani-
mals, like the simplest plants, may be divided without
destroying their vitahty, and every part may become a
perfect individual*. To this class belongs the Hydra,

* Since, therefore, the extreme point to which we can trace animal or-
ganisation is a cell, and all the important processes by which the fabric
is renovated and maintained are performed by the agency of cells en-
dowed with specific properties, — some secreting the bile, others the fat,
others the mucus, and so forth, — it follows, that, upon the integrity of the
structure and function of a cell, or of a cluster of cells, may depend the
maintenance of health ; in other words, that the first germ of disease may
arise, and for awhile lie hidden, in these integral elements of animal or-
ganisation. Hence, we can understand how mental emotions, by disturb-
ing or weakening the vital influence transmitted by the nerves to the cells
of any particular organ, may impair the structure and vitiate the secretions,
and ultimately induce extensive local disease, long after the cause of the
physical derangement has passed away, and is forgotten. Of the truth of
this remark, pulmonary consumption, alas ! affords eveiy day the most un-
equivocal and melancholy proofs. But the Tree of Knowledge yields good
as weU as evil fruit ; and, if recent microscopical discoveries are calculated
to alarm the timid, by shewing what shght causes may lay the foundation of
fatal diseases, on the other hand, they encourage the cheering hope, that,
by patience and perseverance, we may at length learn how to detect the

26 THOUGHTS ON ANIMALCULES.

and the above exposition of its structure renders the
phenomena previously described, namely, the production
of several perfect animals from the vivisection of an in-
dividual, perfectly intelligible.

The formation of the young polypes by 'gemmation
or buds, as in certain plants, is in accordance with this
simplicity of structure. A small protuberance appears
externally on some part of the body of the polype, and
gradually enlarges and becomes elongated ; arms speedily
shoot forth from the free extremity, and a miniature Hydra

first stage of disordered action, and correct the functional derangement,
ere the structure of the organ is seriously impaired. And, since the first
germ of disease is located in the cells, reason suggests, and experience
confirms the propriety of employing our remedial measures in such man-
ner as shall ensure, as far as possible, their direct influence on the inti-
mate structure of the affected organ. Thus, in certain morbid conditions
of the lungs and air-passages, the inhalation of vapour impregnated with
those substances that are known to act beneficially ia such affections is the
most effectual mode of treatment, and that which, above all others, ac-
cording to my experience, holds out the fairest prospect of cure in the
early stage of Consumption, and the most certain alleviation of the dis-
tressing symptoms which but too frequently attend its progress to the
fatal termination. Even with our present limited and imperfect experience
of the effects of the inhalation of certain remedies in phthysis^, such bene-
ficial results have been obtained, that, in the acknowledged inutihty of all
other measures, (not excepting change of climate, which it is the fashion
to estimate very far above its real value), the neglect of this probable
means of cure, and of certain alleviation, cannot be too strongly con-
demned. The importance of the subject will, it is hoped, excuse this
digression.

CELLS, THE ESSENTIAL ORGANS OF LIFE. 27

is formed ; {see pi. i, fig. 4). In a short time the young
separates from the parent, and assumes its individual
existence. Frequently several young ones, in various
stages of growth, appear on the same polype, and even
a third or fourth generation on the young themselves,
before their separation from the parent. Upon an
average, each individual sends out five or six young in
the course of a week ; the progeny of a single polype,
may, therefore, in a few months, amount to hundreds of
thousands.

28 THOUGHTS ON ANIMALCULES.

VI.

THE INFUSORIA, OR FRESH-WATER ANIMALCULES.

From this sketch of the natural history of the Hydras,
we pass to the examination of the group of living animal-
cules sporting in the drops of water between the two
small plates of glass placed in the field of the microscope ;
and, as it comprises species of several families, it will
afford us a satisfactory elucidation of many interesting
particulars relating to the structure and economy of this
class of animals. To examine these objects in detail, we
must successively select a particular species, remove it
from the group, place it in a drop of pure water, and
inspect it under the microscope with different powers ;
beginning with a low magnifier, that we may first obtain
a general knowledge of the form and appearance of the
species, whether single or in clusters; and afterwards
examine the several parts of the body with the most
powerful glasses*. It was by patient and persevering

* The scope of this volume does not admit of practical directions. Mr.
Andrew Pritchard's " Microscopic Illustrations" will be found to contain
the required information.

INFUSORIA, OR FRESH-WATER ANIMALCULES. 29

investigations of this nature, and by experiments con-
ducted with great sagacity and caution, that the eminent
naturalist M. Ehrenberg, discovered the interesting facts
relating to animalcular Kfe, which have so astonished and
dehghted the scientific Avorld*.

Our examination will begin with those animalcules
which are of the simplest structure — the Monads ; but
some preliminary remarks are necessary to elucidate a
few general phenomena, which are observable either in
certain groups, or in the whole class.

The existence of these minute beings having been
first detected in water containing vegetable matter, such
as hay, grass, &c., it was taken for granted that they
were peculiar to certain infusions; hence the term

* M. Ehrenberg's splendid work is intitled "Die Infusionsthierchen
als VoUkommene Organismen. Ein Blick in das tiefere organische leben der
Natur. Leipzig, 1838." It is in one volume, folio, with sixty-four plates,
containing many hundred figures coloured from nature. It is indeed a
most extraordinary production, whether we consider the prodigious labour,
profound knowledge, and eminent talents for observation required for the
successful investigation of the subject, the surpassing excellence of the
drawings, or the marvellous nature of the beings which are therein de-
lineated and described. The reader who has not seen this work, though
he may have surveyed the beautiful and curious forms which these unpre-
tending pages are designed to illustrate, can have no adequate idea of the
fantastic shapes, and the almost endless diversity of form and structure,
which animal existence assumes, even in our own planet, in the regions
from which the microscope withdraws the veil.

30 THOUGHTS ON ANIMALCULES.

Infusoria given to this class of animals, in allusion
to their supposed origin. This name is still employ-
ed as a general designation, although it has long been
known that the presence of animalcules in infusions
has no necessary relation to the vegetable ingredients,
except so far as the decomposition of the latter may
tend to the production of a proper medium, for the de-
velopment of the invisible eggs, or germs, of these crea-
tures, which are everywhere present. The essential
characters of the Infusoria — in other words, those points
of their organisation in which they differ from all other
animals — consist in their bodies being destitute of any
true articulated or jointed limbs and locomotive mem-
bers or feet; their varied movements being perfonned
by means of peculiar processes, or filaments, which are
always in motion, and are termed Cilia*, from their sup-
posed resemblance to the eyelashes. The ciha, in many
species of Infusoria, are more or less generally distri-
buted over the surface of the body ; in others, they are
disposed in one or more circles around the mouth or
aperture of the digestive organs ; and, in some, are ar-
ranged in zones on one or more circular, or semicircular
projections, on the upper part of the body. In the last
modification, the successive action of the rows of cilia

* Cilia, the plural of cilium, an eyelash.

INFUSORIA, OR FRESH-WATER ANIMALCULES. 31

produces an apj)earance of a rotatory motion, like that
of a wheel on its axis; and this resemblance is so
striking, that the name Rotifera, or wheel-bearing ani-
malcules, is given to the Infusoria possessing this char-
acter; which are also further distinguished, by a more
highly endowed organisation than the other species.
The Infusoria are therefore arranged by Ehrenberg in
two classes, which are respectively designated Polygas-

TRIA, and EOTIFERA.

32 THOUGHTS ON ANIMALCULES.

VII.

THE POLYGASTRIA, OR ANIMALCULES WITH MANY
STOMACHS.

The Polygastria, {many stomachs), as the name im-
ports, are characterised by having a digestive organ,
which, instead of being a single pouch or cavity, as in
the Hydra, is composed of numerous little globular
bladders, {sacs, or sacculi), connected together by one
common tube ; and these clear globular cells or stomachs,
receive and assimilate the nutriment when in a suffi-
ciently molecular or divided state. From the trans-
parency of the bodies of the animalcules, the cells, when
filled with coloured food, are easily distinguished, as we
shall presently prove by an interesting experiment.

The Polygastria present great diversity of figure;
their movements are performed by the cilia, which are
distributed over the body; they increase either by
spontaneous division, or by gemmules or buds. Tliis
class comprises the minutest forms of animal life hitherto
reached by the most powerful microscope. Some kinds
(JSIonas vibrio) do not exceed one three-thousandth of a

THE POLYGASTRIA. 33

line (one-twelfth of an inch) in dimensions. The largest
species; as, for example, the Stentors, are visible to the
naked eye ; and these are not more than two-thirds of a
line in length. But these living atoms are often clus-
tered together in such inconceivable numbers, as to
form considerable masses, of various colours. The Poly-
gastria occur both in fresh and salt water, in humid
earth, peat-bogs, and morasses. Our remarks will be
limited to the living species contained in the group to
which the reader's attention was first directed.

ViBRATiLE Cilia. — As these processes are common
to the whole class of Infusoria, and only differ in the
several types in number, position, and relative magni-
tude, it is desirable, in this place, to give a more par-
ticular account of these remarkable instruments, which
recent discoveries have shewn to exist also in the in-
ternal organs of man, and of the other vertebrated
annuals, and to be the agents by which many of the
most important functions of the animal economy are
performed.

These delicate filiform appendages, appear like very
minute hairs rapidly vibrating in the water, and are only
discernible by the aid of a good microscope. They are
constantly performing a rotatory or circular oscillation;
and. as there is a bulb at the base of each cilium, it is

D

34 THOUGHTS ON ANIMALCULES.

supposed that a slight degree of tension on the bulb
causes rotation at the base, and a more extensive mo-
tion at the extremity of the cilium, which thus describes
in its revolution a cone, whose apex corresponds with
the bulb. As we cannot separate the idea of muscular
fibre from animal motion, it is conjectured that the
cilia are impelled by definitely arranged muscles; and
Elirenberg believes that he has detected muscles, and
even the disposition of their fibres, in some of the larger
Infusoria.

In this group of VorticellcB, {see pi. iii, fig. 3), the cilia
are seen in rapid motion, and occasioning currents in
the surrounding fluid; and, as this Stentor, (pi. ii, fig. 13),
traverses the water, the particles of foreign matter near
it are agitated by the eddies induced by the vibrations
of its cilia; and in the Rotifer, (pi. xn, fig. 3), the cur-
rents are still more distinct, and are seen to run to and
from the mouth of the animal ; we shall have occasion
to revert to this phenomenon hereafter. The cilia are
so minute, that, even with the highest magnifiers, their
figure, position, and the direction of their motions can
alone be detected: their internal structure has hitherto
eluded observation. They are most distinctly visible
when almost all the water from the slide has evaporated,
and left the animalcules nearly dry: the cilia are then
elongated to their utmost extent, and in strono- action.

THE VIBRATILE CILIA.

35

The subjoined sketch of the cilia on the rotatory
organs of the common Wheel-animalcule, {Rotifer vul-
garis), hereafter described, copied from Ehrenberg, will
illustrate the above description. The cilia {a, a) are
here represented as shewn by the highest powers of the
microscope.

LiGN. 1. — The Upper Part of the Body of the Rotifer, or Wheel Animalcule,
highly magnified,

a, a, The Zones of Cilia. h, The Proboscis, bearing the Two Eyes.

c, The Jaws and Teeth.

d2

36 THOUGHTS ON ANIMALCULES.

YIII.

THE MONADS.
Plate II.

In tlie group under tlie microscope, some minute
points, or globules, of various colours, may be observed
gliding rapidly along in various directions: these are
called Monads. A few have been transferred to a drop
of water, and, to distinguish their true characters, we
must view them with glasses that magnify from 300
to 400 times in linear dimensions. We may now per-
ceive {see pi. II, figs. 3, 7), that each individual is an oval
or spherical transparent cell, containing granules, or
little specks, of some coloured matter. Some are with-
out eyes, or any sensible organs but the cilia, and one or
more filiform spines or bristles, (pi. ii, figs. 4, 5, 8);
others have a red eye-speck, (ocellus); and many have in-
durated cases or shells. They vary in size from one two-
thousandth to one three-thousandth of a line in diameter:
a drop of water may, therefore, contain 500,000,000.
Some are of a bright green colour, {Monas grandis)\
others pink, red, yellow, bluish, ochreous, (pi. ii, figs.

THE MONADS. 37

4, 6), &c. ; and the floating coloured slime whlcli some-
times appears in the water, is an aggregation of count-
less hosts of these beings. One species, which is of
a hyaline (glassy or crystalline) appearance, {Monas
crepvsculum), and but one two-thousandth of a line
in diameter, is of a spherical form, and is said to
be carnivorous; whitish masses, visible to the naked
eye, are often formed by the accmnulation of innu-
merable myriads of this species. The Monads never
vary in form, whether they are in motion or at rest.
They increase by self-division either into two, or four,
parts, (pi. II, figs. 3, 7). When this process is about to
take place, the granules within the integument, or case,
seem to be divided by a transverse line: this gradually
becomes more apparent, and at length the containing
case itself contracts along the course of this line, and
the monad appears double, (pi. ii, figs. 7 b,S). Both parts
now have an impulse to separate, and an entire division
soon takes place: the two become perfect individuals,
and swim oif in opposite directions.

In the Cloak Monad, ( Chlamidomonas), this interest-
ing process is beautifidly exemplified. Fig. 7, shews a
single animalcule, and another dividing into two: and
in fig. 3, two Monads are seen separating into four.
The same process in another species, (Monas vivipara),
is represented in fig. 8.

38 THOUGHTS ON ANIMALCULES.

The monads we have just examined are single, free
animalcules; but others of the same family are either
permanently or temporarily attached to a case, or sup-
port, in definite groups.

I. The GoNiUM, or Tablet Monad, (pi. ii, fig. 2).— This
flat, quadrangular, hyaline body, studded with sixteen
bright green spots, is a group of individual monads at-
tached to a common tabular case, or support. If we
view this group with a power magnifying 400, we per-
ceive that each of the green spots is an animalcule
furnished with two horns, and six little processes that
pass off from the margin, and by which it is connected
with its neighbours, (pi. ii, fig. 2 a). The mode of in-
crease in these clusters is exceedingly curious. A sim-
ple crucial division takes place in the case, or support,
which is thus divided into four portions, each containing
four monads : these rapidly subdivide into sixteen, the
normal number; and so the process goes on, ad in-
finitum.

In the Gonium we have an example of the partially
separated monads continuing in organic connexion, and
always forming definite groups of individuals. This
fact will prepare us for the examination of a common but
most remarkable type of these animalcules, the Volvox
glohator; which is that revohdng semi-transparent orb.

THE VOLVOX. 39

dotted all over with green spots, and fringed with cilia,
now in the field of view, (pi. ii, fig. 10).

II. The YoLvox, or Revolving Monad, (pi. ii, figs. 9,
10, 11, 12), — The Volvox glohator, or Globe Volvox, was
discovered 150 years ago by Leeuwenhoek, and was sup-
posed to be a single animal, until the recent improve-
ments in the microscope revealed its true character, and
shewed it to be composed of a group of monads, fixed in
a globular integument, or case, each little green point
being a perfect and isolated individual, in organic con-
nexion with the case and the surrounding monads. By a
power of 500 the globe is shewn to consist of a family
of polygastric animalcules, uniformly distributed over the
spherical integument. Fig. 12, pi. ii, represents a part of
the globe highly magnified: in the centre is seen a group
of six individuals, produced by spontaneous fissuration.
The monad of the Volvox, (pi. ii, fig. 11), has a red eye-
speck, two long spines or horns, and six processes by
which it is connected with its kindred animalcules. The
little globular cells of the digestive organs are distinctly
visible. In fact, we have here numerous perfect monads,
partially imbedded in, and distributed over a hollow
spherical carapace, or case, instead of on a tabular one
as in the Gonium.

The Volvox increases by spontaneous fissuration, like

40 THOUGHTS ON ANIMALCULES.

the other monads, but it presents an extraordinary
peculiarity. Jf we look attentively at the large Volvox
now slowly revolving through the water, bristling with
long filaments, which are the protruded horns of the
monads, (pi. n, fig. 10), we may discern within the
globe several lesser ones, apparently differing from the
outer globe only in size: these are new generations
ready to escape, and go through the same changes as
the parent group. These internal globes of young Vol-
voces are produced, in consequence of the spontaneous
division in this species of monad, taking place only from
the inside of the globular envelope. New spherical
groups are thus thrown off" into the cavity of the parent
carapace, where they remain till they attain a certain
stage of development. Some part of the integument of
the outer globe then gives way, {see pi. ii, fig. 9), and the
young ones escape, and commence their independent
existence. The internal globes are generally six or eight
in number, but occasionally as many as twenty occur ;
they are green, have an entire margin, and may some-
times be seen to move while within the primary globe.
There are apertures by which the water has free access
to the interior of the whole series. The revolving mo-
tion of the Volvox, by which it is propelled through the
water, is effected by the incessant action of the vibratile
cilia, and is automatic, (that is, anorganic or involuntary

THE VIBRIO. 41

action), by wliich means the aeration of the tissue and
fluids is effected, the whole mass brought into contact
with fresh portions of water, and the colony of monads
transported from place to place; and thus supplies of
food are constantly obtained.

III. TheYiBRio,OY Trembling Ammalculey(i^\. n.fig. 1).
— Some extremely fine hair-like bodies are seen moving
near the Volvox; these are groups of the polygastria
termed Vibrio, of which several species are commonly
present in water containing other animalcules. But lit-
tle is known of their structure, in consequence of their
extreme minuteness; for each filiform body is not an
individual, but a series of many, united together in a
flexible chain, from imperfect spontaneous transverse
division. This chain is straight when motionless; and
locomotion is performed by successive rapid undulations,
{see pi. II, fig. 1).

42 THOUGHTS ON ANIMALCULES.

IX.

THE VORTICELLINA, OR BELL-SHAPED ANIMALCULES.
Plate III.

The object next to be examined is a portion of the
mucus, or jelly, that we observed adhering to the sprig
of the aquatic plant when first brought under our
notice, {see page 9). Viewed with a moderate power,
this apparent film of jelly is found to be composed of
clusters of living animalcules, of very elegant forms.
One part resembles a minute shrub, (pi. iii, fig. 1);
another portion consists of groups of bell-shaped cups,
suspended by threads, or filaments, (pi. iii, fig. 3); and,
associated with these fixed groups, are several free ani-
mals, of the same general configuration, which are
traversing the water in various directions, (pL ii, figs. 13,
1 5). All these animalcules are Polygastria, distinguished
from those previously described by the cilia being ar-
ranged around the region of the mouth, or aperture for
the food, and by a peculiar modification of the di-
gestive canal. In these Infusoria the body is either of
a funnel, or bell-like shape, having the upper border

THE STENTOR. 43

garnislied with one or more zones of cilia; these organs
being in most of the species lunited to that region, and
not diffused generally over the body, as in the monads.
They increase by spontaneous division and genunation,
and are destitute of a sheath, or carapace. We have
species of three genera before us.

I. The Stentor, ov Trumpet Animalcule ,(^1. ii,figs. 13,
14, 15, 16). — The animalcules now in view, and which
are seen in different attitudes, (pi. ii, fig. 14), are called
Stentors. There are several species, some of which are
of a rose colour, others blue, green, (pi. ii, figs. 13, 14),
&c. They are comparatively of a large size: one species
{Stentor Mulleri) is half a line in length, and therefore
visible to the naked eye. The body of one species is
garnished with cilia, and has a crowm of larger cilia
around the aperture, which is spiral. The Stentors have
no pedicle, but they can fix themselves by the point of
the base. They transport themselves through the water
with rapidity, by means of their coronets of cilia. They
are very voracious: in the body of one specimen may
be seen several monads, which it has swallowed, (pi. ii,
fig. 13).

The Multi-shaped Stentor, (^S. polymorphus), is of a
green colour, and varies its form greatly in different

44 THOUGHTS ON ANIMALCULES.

positions, (pi. ii, figs. 14, 15). This animalcule often
occurs in immense numbers, appearing like a crust of
jelly on the stems and twigs in the water, {see pi. ii,
fig. 16).

The Blue Stentor (pi. ii, fig. 13) has a longitudinal
crest, or ridge, extending down the side of the body,
(pi. II, fig. 13 4

II. The Bell-shaped Animalcules, or Vorticellce, (pi.
III). — These are the most common, and at the same time
the most elegant, of the Polygastria. They are met with
in clusters of myriads, attached to leaves, twigs, roots,
or other bodies in the water. They quickly appear in
vegetable infusions; and the transparent mucus ob-
servable on aquatic plants, and in vessels containing
infusions, will generally be found to consist of some
species of this genus. They are often attached in
clusters to the shells of the small Crustaceans (Mon-
oculus, Cyclops, &c.) that abound in the water. The
common Water-Flea is frequently infested with them, and
may be seen swimming about ^^ ith groups of Vorticellae
affixed to its case.

The body of these elegant creatures, (pi hi, fig. 3), is
bell-shaped, and has a coronet of cilia on the upper bor-
der. The margin of the cup, or bell, is enlarged and

THE VORTICELL^. 45

projecting. From the middle of the under part^ a long
tendril, or spirally contractile pedicle, or stalk, proceeds,
and is fixed to a common base, with numerous other in-
dividuals,— the whole forming a group, or cluster. The
size of the body, without the stalk, is about one twenty-
fourth of a line. The pedicle by which the body is
fixed to its position, is furnished with a long muscle, by
means of which it can be suddenly contracted into a
spiral coil, apparently at the will of the animal, (pi. iii,
fig. 3); the Vorticella has thus considerable latitude of
motion, though restrained within the limits of its tether.
This contractile action is continually going on, — now
in one or two individuals only, then in several; and
often the whole group suddenly shrinks down into a
confused mass, and the next instant expands, and every
little bell becomes fully developed, with its cilia in rapid
oscillation.

YoRTICELLiE FED WITH CARMINE, (pi. IH, figS. 1, 2,

3, 4, 6). The circular eddies, or whirlpools, produced
in the surrounding fluid by the zones of cilia are visible
in ordinary conditions; but they are rendered much
more distinct if a few particles of colouring matter are
introduced into the water; and by this means another
interesting part of the structure of these animalcides
is made manifest. Let us try the experiment. I place

46 THOUGHTS ON ANIMALCULES.

a drop of a solution of carmine* in the water between
the plates of glass containing the Vorticell^e : the fluid
in which they are floating now appears turbid, and full
of grey particles, which are thrown into rapid motion
by the vibrations of the cilia, and currents are seen
passing to and from the mouth of the animalcules. In
a few minutes the water gradually becomes clear, and
several round spots of carmine are apparent in the body
of each of the Vorticellte, (pi. in, figs. 3, 6). We have,
in fact, caused their Httle stomachs to be filled with
colouring matter, and can now distinguish their number
and arrangement. If the body of the Vorticella were
a mere vase or cup, or a simple cavity like the digestive
sac of the Polype, it is obvious that the carmine must
have collected into a single ball or mass ; but this is not
the case ; on the contrary, the colour appears in distinct
round spots, from having accumulated in globular cells ;
and, by carefid investigation, the tube connecting these
cells may be detected.

* Sap-green, indigo, or carmine may be employed ; it is necessary to
use colour free from adulteration. The idea of colouring the water con-
taining animalcules, with the view of rendering their transparent organs
more distinct, originated with M. M. Trembley and Gleichen ; but no im-
portant results were obtained by the experiments of these observers. In
the hands of M. Ehrenberg this method of investigation proved emi-
nently successful, and led to the discovery of the internal structure of the
Polygastria.

THE VORTICELL^.

47

The highly magnified view of a single Annulated
Vorticella, ( Vorticella convallaria), in the annexed lig-
nograph;, very distinctly displays the zones of cilia, and
the oflobular stomachs.

"-\#f#

I =■ ^ '-s^i T^ „ ,/

LiGN. 2. — A detached Vorticella convallaria, highly magnified,
a. The Cilia. 6, 6, The Globular Stomachs.

The Yorticellie, like the Monads, increase by self-di-
vision. A fissure beo^ins to extend throug-h the longest
diameter of the cup, and continues till it is completed,
(pi. Ill, fig. 2), the two portions in the meanwhile ra-
pidly acquiring the perfect form of the species. A
fringe of ciha next appears round the base of each, (pi.
HI, fig. 3 «, and fig. 4), and the bodies then separate
from the pedicle, which soon perishes. The liberated

48 THOUGHTS ON ANIMALCULES.

Vorticellae roam free for awhile, and at length throw
out a fresh pedicle, become fixed, and ultimately pro-
duce another colony of individuals by spontaneous fis-
suration.

III. The Arborescent VoRTiCELLA, ((7«rcAe5mm, pi.
Ill, fig. 1). — In some kinds of Vorticellina the pedicle, in-
stead of being single down to its attachment, springs from
a common trunk, the individual bodies hans^ino^ at the
extremities of the branches like the flowers of the hare-
bell : this results from imperfect self-division. In tliis
species, the group commences by a single VorticeUa
dividing longitudinally into two portions, and thus pro-
ducing two perfect individuals, which are connected by
a forked stem: these two divide into four, which, in
like manner, are united by their pedicles ; and so the
process goes on, till the limits of this special type of
development are reached. In pi. iii, fig. 2, is shewn
the manner in which the longitudinal fissuration takes
place. Two distinct cups or bodies are formed, and are
seen in progress of separation : each is provided with a
distinct set of cilia and digestive organs, as denoted
by the coloured spots in each bell : in a short time the
division would be completed, and each animalcule sup-
ported on a pedicle. The body of this animalcule,
when arrived at maturity, separates from the parent

THE TREE VORTICELLA. 49

stem in the same manner as tlie former species, tra-
verses the water in freedom for awhile, and then be-
comes fixed, and goes through the allotted phases of its
existence.

In another kind of Carchesiunii the stem is also spi-
rally contractile, and branched by imperfect self-division,
and the clusters appear like miniature trees or shrubs.

LiGN. 3.— The Carchesium, or Tree Vorticelxa.
a. The Group expanded. b. The whole Group contracted into a globular mass.

One of these groups is here represented, as seen with a
low power; it is shewn extended in fig. a, and contracted
into a ball, in fig. b.

Physiological Summary. — In this rapid survey of
the Polygastria contained in the drops of water under
review, the principal chai'acters of this class of animal-

£

50 THOUGHTS ON ANIMALCULES.

cules have been exemplified. The digestive organs
consist of a series of globular stomachs, connected by a
common tube, which allows entrance to the food, and
exit to the effete particles. The food is brought to the
mouth by the currents produced in the water by the
cilia ; aeration is performed by the agency of the same
organs; and the increase of the species is effected by
spontaneous division, each part, like the severed por-
tions of the polype, quickly growing into a perfect in-
dividual. Some are fixed to one spot in youth, but
become free when arrived at maturity, and are thus
capable of transporting themselves through the water
to locahties possessing the conditions required by their
organisation.

There are proofs of a muscular system, however sim-
ple, in the motions of the cilia, and in the rapid con-
tractions and changes of form which are exhibited in
certain species. No definite nervous system has been
detected, but there can be no doubt that a nervous in-
fluence is difiiised through their structures; and the
existence of an eye-speck, or \dsual point, however
rudimentary, denotes a distinct nervous centre*. Eyes

* " There must, therefore, be nerves or conductors ofthat influence for
the various movements, whether we consider them as voluntary, or re-
flex, that is, induced by stimuli, either within or without the body, upon
the contractile fibre." — Professor Owen.

THE POLYGASTRIA, 51

have been observed in fifty species : the colour, or pig-
ment, is in most instances red, but in one genus it is
black.

The Polygastria, when examined at night, are found
to be moving as actively as in the day ; in fact^ they
seem never to require repose; a phenomenon diflScult
to be explained, unless we assume that their actions are
automatic, or involuntary.

In the next division of animalcules, we shall find a
marked difference, both in structure and habits. The
increase of the species is no longer effected by spon-
taneous division or fissuration ; the organs of digestion
are less numerous, and of a higher type; and, though
locomotion is performed by ciha, the position and ar-
rangement of these instruments are considerably modi-
fied.

-X^JJ) o

e2

52 THOUGHTS ON ANIMALCULES.

THE ROTIFERA, OR ROTATING ANIMALCULES.

The terra Kotifera, or Wheel-bearing Animalcules,
by Avhich this class is distinguished, refers to the ap-
pearance assumed by the zones, or circular rows of cilia,
around the upper part of the body, when rapidly vibrat-
ing; and which so closely resembles that presented by the
rotation of a wheel, that every one who sees the pheno-
menon is struck with the similitude. The resemblance
is heightened by the wavy or undulating motion by
which one cilium is carried out of sight, while the next
is visible ; for this alternate presence and disappearance
of the image contributes to the optical illusion. The
cilia do not occur on any other part of the body, as in
the Polygastria; the semblance of such processes on
some of the larger Rotifera is produced by parasitic
plants*.

The E.OTIFERA possess a definite form, and rotators
formed of cilia ; many species have a false foot, or pedi-

* Ehrenberg.

THE ROTIFERA. 53

cle. The rotatory organs are rows of cilia, placed on
circular or semi-circular eminences on the upper part of
the body. In some species, the cilia are in a single
series; in others, in several rows of different forms:
and in one genus, (Stephanoceros), they assume the
character of ciliated tentacula, rather than that of
simple vibrating processes. There are distinct muscles
for the internal and external movements. In some
species, the pedicle has a sucker at its extremity, which
serves to fix the body during the rapid motions of the
rotators ; and, without this power of attachment, the
upper part of the body would be drawn in by the ac-
tion of these organs. The digestive canal is a tube more
or less straight, which in many genera is provided with
jaws and teeth : these, like the masticatory organs in
birds, are situated low down, are very distinct, and pre-
sent considerable diversity of form and arrangement.

Masticatory Organs of the Kotifera. — The
reader, from what has already been submitted to his
notice, is familiar with the marvellous powers of the
microscope, or he would probably receive with some
degree of scepticism the following account of the jaws
and teeth of animalcules, none of which exceed two-
thirds of a line in length, and are, therefore, but just
perceptible to our unassisted vision.

54 THOUGHTS ON ANIMALCULES.

The pharynx, or narrow part of the upper portion
of the alimentary canal, is surrounded by four hemi-
spherical muscular masses, placed opposite to one an-
other like the limbs of a cross, and which are very
obvious when in motion. Two of these masses are
armed with jaws and teeth, which, being formed of a
hard substance, can be easily disengaged from the soft
parts by crushing the animalcule between two plates of
glass. These organs exist under several types, which
are so constant and regular, that Ehrenberg states
the Rotifera might almost be arranged, like quadru-
peds, according to their teeth.

Some have a long tooth in each jaw, (as in the No-
tommata, lign. 4), capable of being protruded, and thus

LiGN. 4. — The Jaws and Teeth of the Notommata, highly magnified.

a pair of powerful nippers is formed, by which the

JAWS AND TEETH OF ROTIFERA. 6^

animalcule seizes and tears to pieces its living prey;
for the Rotifera possessing this dental apparatus are
carnivorous, and very rapacious. Others have several
teeth fixed at the moveable extremity of each jaw,
forming, as it were, toothed hammers, which strike
upon a solid body, the food being thus comminuted, or
crushed, as upon an anvil {Brachionus, pi. xii, 1, 2,
and lign. 5, fig. 2).

LiGN. 5. — Fig. 1, Jaws and Teeth of the Floscularia, highly magnified.
Fig. 2. Jaws and Teeth of the Brachionus.

In some species each jaw is of the shape of an open
stirrup, and the two are placed horizontally, the trans-
verse bars being opposed to each other. The teeth lie
across the arch, and are fixed by one end to the upper
transverse process; the lower process gives support to
the muscles. This structure is well exemplified in the

56

THOUGHTS ON ANIMALCULES.

jaws of the Rotifer (ligns. 1 and 6) and of the Floscu-
laria, (hgn. 5, fig. 1).

LiGN'. 6. — Jaws and Teeth of the Rotifer, highly magnified.

In other species, with the same type of masticatory
apparatus, the jaws are furnished with several teeth;
as in the Stephanoceros, or Crowned Animalcule, in
w^hich there are two distinct sets of teeth on each side.

as shewn in the annexed figures.

J 2

LiGN. 7. — Jaws and Teeth of the Stephanoceros, highly magnified.

Fig. 1. The Upper Set of Teeth, marked a, in fig. 2.

Fig. 2. Tlie Double Set of Dental Organs, iu their natural position.

Fig. 3, The Lower Set of Teeth, marked h, in fig. 2.

Respiration, or, more properly, the aeration of the
fluids, is effected in the Rotifei'u by the constant in-
troduction of fresh water tlirough one or more aper-

THE ROTIFERA. 57

tures near the neck^, {see pi. xii, fig. 3, c)\ and in some
kinds there are internal oval bodies, composed of gran-
ules, or corpuscles, which have constantly a tremulous
motion, and are supposed to perform the office of bran-
chia, or gills.

There are indications of nervous centres, or ganglia^
in several genera ; and from one to four punctiform eyes
have been observed in 150 species: in some there ap-
pears to be a ganglion, or nervous mass, immediately
beneath the eye. Some kinds are oviparous, others
viviparous. An elongated bag or sac, in which the
ova, or eggs, are formed, is distinctly visible; but few
eggs are developed at the same time. The ova, in many
species, equal in size one-third of the body of the ani-
malcule. They retain their vitality for almost an un-
limited period, and are transported by the water, and
wafted by the winds — for, whether dry or moist, they
remain uninjured — till, thrown into the conditions suit-
able to their organisation, they become developed, and
the apparently pure waters suddenly teem with myriads
of highly organised beings. Even the adult animals of
some species — the common Rotifers, for instance — after
being apparently dried up for several years, will start
into life upon the addition of a^ few drops of water,
and throw their rotatory organs into full play, as if
roused from a refreshing slumber.

58 THOUGHTS ON ANIMALCULES.

XL

THE FLOSCULARIA, OR FLOWER-SHAPED ANIMALCULES.
Plates IV, V, VI, VII, VIII.

The Rotifera we shall first examine have one simple,
continuous, rotatory organ, the margin of which is more
or less deeply lobed, or undulated. The body is in-
closed in a cylindrical case, or sheath, which is fixed at
the bottom, and open at the upper extremity, from
which the rotator and upper part of the body can be
protruded. This family is named Floscularia^ from
the flower-like appearance of the body when expanded ;
it comprises six genera, in which are some of the most
interesting animalcules of the whole class.

I. The LiMNiAS, or Water-Nymph^ (Z. ceratophylli, pi.
iv). — Here is a group of eight individuals, accidentally
clustered together, of the Hornwort Limnias*, an animal-
cule with an isolated tubular sheath, into wliich it can

* So named, because often found on the plant called Hornwort, or
Ceratophyllum.

THE FLOSCULARIA. 59

retreat and wholly conceal the body, when the water is
agitated ; as shewm in pi. iv, a. The rotator, which is
fringed with cilia, and divided into two lobes, presents
a highly interesting spectacle when fully expanded ; as
in pi. IV, b. The tube, or sheath, is at first clear and
transparent, but becomes of a yellowish brown colour ;
and is frequently coated with foreign matter, which
adheres to its viscid surface. In the young state the
Limnias has two eyes, that disappear with age. The
length of the sheath and body is from one-half to two-
thirds of a line, and therefore recognisable by the naked
eye. The jaws and teeth are of the type figured page
b6i fig. 1 ; but they cannot be seen in the example
before us, wliich is a remarkable cluster of several in-
dividuals of various ages. Four or five eggs are per-
ceptible within the tube of the largest animalcule,
(pi. IV, c c), ,

II. The Melicerta, or Honey Floscularia, (pi. v). —
This is a tubular animalcule, about two-thirds of a line
in length; it differs fromHhe Limnias, in having the
rotatory organ divided into four lobes, the two uppermost,
of which are the largest. The species before us is the
Beaded Melicerta, (3/. ringens\ so called from its
case being made up of little corpuscles, which give it a
granulated, or beaded character. Its body is liyaHne,

60 THOUGHTS ON ANIMALCULES.

(that is, of a crystalline appearance). The sheath is iso-
lated, granular, and of an elongated conical form, and is
composed either of lenticular, hexagonal, or pentagonal
bodies, produced by a viscid exudation from the base
of the animal, that hardens in the water. The en-
velope of the body is at first transparent, the granular
coat being of subsequent formation. If the newly-
hatched young are put into water, and a drop of a
solution of carmine or indigo be added from time to
time, the case will be party-coloured ; for zones of red
or blue globules will be formed, alternating with
white ; as in pi. v, fig. 5. A very young example is
seen, fig. 3, w^ith but one ring of corpuscles, which is
coloured by the carmine: in figs. 2, 4, the same in-
dividual is represented when of more advanced age,
and the sheath consists of several zones of corpuscles.

The young has two eyes, which disappear in the
adult.

Near the neck there are two respiratory tubes, (pi. v,
fig. 5, a a), which are very prominent in the young
state.

The Melicerta, like the Limnias, is an exceedingly
susceptible animal, concealing itself within its case upon
the slightest agitation of the water. It is a beautiful
object when its rotatory organ is fully spread out, and
the cilia in rapid motion.

THE FLOSCULARIA. 61

III. The Flower-shaped Animalcules, or Floscula-
rice, (pis. vi, vii, viii), properly so called, are very elegant
types of the family, and are distinguished by the pecu-
liar character of the rotator, which is divided into more
than four lobes. In this beautiful species, the Elegant
Floscularia, {F. ornata, pi. vi), the sheath is hya-
line, and the rotatory organ consists of six lobes, armed
with very long cilia. The body is capable of being
protruded beyond the case almost to its base, (pi. vi,
fig. 1), and can be drawn in so as to include the cilia,
(pi. VI, fig. 2), in which position the sheath is corru-
gated in circular folds. From the transparency of the
sheath and body, the internal organs are distinctly visi-
ble. The jaws and teeth (see pi. vi, fig. 1, a, and lign.
5, fig. 1) are seen beneath the pharynx, or constriction
of the alimentary canal, and several Monads and other
minute polygastrians in the stomach, (pi. vi, fig. 1, h).
A young one, with two red eyes, is visible in the ovisac,
(fig. 2,c). In another example, (pi. vii), the body is par-
tially protruded over the top of the sheath, within
which are three well-developed eggs.

IV. The other species under the field of view, the
Horned Floscularia, {Flosculhria proboscidea, pi. viii),
has the rotator divided into six lobes, with shorter cilia
than in F. ornata, and these surround a horn, or proboscis,

62

THOUGHTS ON ANIMALCULES.

which is also armed with ciHa, (pi. viii, a). This ani-
malcule is about two-thirds of a line in length; the
sheath, one-third of a line; and the egg, one°twenty-
fourth of a line.

THE STEPHANOCEROS. 63

XII.

THE STEPHANOCEROS, OR CROWNED
ANIMALCULE.

Plates IX, X, XL

This is an exceedingly interesting animalcule, from
one-half to one-third of a line in length, and is gene-
rally found attached to the stem, and under surface of
the leaves, of the Water-lily, and other aquatic plants*.

* Having seen the figures of the Stephanoceros in the splendid work
of M. Ehrenberg, I was very desirous of obtaining living specimens for
examination, not being then aware that this animalcule had already been
collected in England by Mr. Dalrymple.

Mr. Hamlin Lee, at my request, undertook to search for it in the
pools and streams on Clapham Common, and, after several weeks' diligent
examination of the aquatic plants in various localities, he obtained, in
October, 1842, several individuals on the leaves of the Nxjmphea alba,
growing in the lake behind Grove -House— a most prolific locality for all
kinds of fresh-water Infusoria. It has since been found in other ponds,
and particularly in that called the Black Sea, on Wandsworth Common,
near the railway station. It is comparatively rare, and the past summer
has been remarkably unfavourable for its development, but few exam-
ples having been observed even in its favourite haunts. While living at
Clapham Common, we were always able to keep a stock of the Stepha-
noceros in glass jars with water containing aquatic plants; but at my

64 THOUGHTS ON ANIMALCULES.

The Stephanoceros appears under the microscope
like a cylindrical vase, as clear as crystal, surmounted
by a crown formed by the convergence of the points of
five long arms, or tentacula, each fringed with about fif-
teen row^s of delicate, short, verticillate cilia, which are
in constant oscillation, (see pi. ix). The vase contains
several bodies of different colours: these are the internal
organs, and the Monads and other polygastrians that
have been swallowed. The rotatory organ in this ani-
malcule is wholly unlike that of any other of the class.
It is deeply divided down to its base into five long pro-
cesses, which may be regarded as ciliated tentacula, for
they are flexible and prehensile, and employed by the
animal to retain the prey brought within the vortex
produced by the vibrations of the cilia. The arms are,
however, limited in their action, and, so far as my ob-
servations extend, do not appear capable of being
lengthened and shortened, or of bending outwardly
and laterally, like the tentacula of the Hydra*.

present residence the attempt to preserve these animalcules alive, even
for a few days, has been unsuccessful, and the eggs have in no instance
reached maturity. As the precaution was taken to supply them with
water from their native lakes, the mortality must be ascribed to some
local condition of the atmosphere. The descriptions in the text refer to
observations made in 1843 by me and my late assistant Mr. H. Lee, now
Conservator in the College of Surgeons of Edinburgh.

* From these ciliated arms, which are arranged around the mouth as

THE STEPHANOCEROS. 65

The transparent case, or mantle, which invests the
body of the Stephanoceros, is not an open rigid tube, as
in the Melicerta, but a flexible integument, which is
thrown into annular folds or corrugations when the
animal contracts itself; and, as the upper margin of this
mantle is attached like a collar round the body, near
the base of the rotators, its border becomes inflected
when the animal shrinks down towards the bottom of
the case, (see pi. ix, fig. 2), the tube being then like
the introverted finger of a glove. In this position the
tentacula are brought close together, side by side ; and
when the creature is about to protrude, the extremities
of the arms first appear united into a point, which
gradually lengthens, till the rotatory organs are wholly
excluded, and assume the form of an elongated dome, the
base of which surrounds the mouth. In some positions
the crown is depressed, and resembles in shape the cu-
pola of a mosque. From the different phases assumed
by the Stephanoceros, and its constant activity when
vigorous, — for it will shrink into its crystal cell the in-

in the marine polypes, (the Bryozoa, or moss animals, so named from
their investing other bodies like moss, of which the common Flustra is
an example), the Stephanoceros may be regarded as the link which unites
the Rotifera with the cilio-brachiate {arms with cilia) polypes. The
manner in which the arms of this animalcule are protruded and withdrawn,
will remind the experienced observer of the similar action in the Flustrse,
&c.

F

66 THOUGHTS ON ANIMALCULES.

stant the stage of the microscope is slightly struck, and
as quickly reappear and vibrate its cilia, — and the in-
teresting internal phenomena it presents, it is an object
of all others the most calculated to arrest the attention,
and gratify the curiosity of the general observer, as well
as of the accomplished naturalist*.

The Stephanoceros has a single red ocellus, or eye-
speck, in its young state ; and there are near the base of
the rotators two minute round bodies at the origin of
each arm, (pi. ix, fig. 1, «), that are supposed to be
ganglia^ or knots of nervous matter. On each side the
body, in every specimen that came under my examina-
tion, a dark oval granular mass was observable, (pi. ix,
fig. 1, b), which, seen with a high power, appeared to con-
sist of corpuscles that were always in tremulous motion.
These bodies would sometimes spread out very consi-
derably while under view, and the corpuscles were
then more distinct and less closely aggregated. These

* There will be found considerable discrepancy between the descrip-
tion in the text, and the figures of Stephanoceros Eichornii given by
M. Ehrenberg, and repeated by M. Mandl, {Traite pratique du Mi-
croscope. Paris, 1839). The Clapham Stephanoceros is probably either
a different species or variety. If it should prove to be specifically dis-
tinct from the Prussian Stephanoceros, I would propose to name it -S*.
Ehrenhergi, as a tribute of respect to the illustrious philosopher, whose
labours have so largely contributed to the advancement of physiological
science.

OVA OF THE STEPHANOCEROS. 67

organs probably perform the function of gills, or hran-
chicB.

There are visible muscles, by which the motions of
the body are effected. The stomach is ample, and situ-
ated immediately beneath the mouth: it generally
contains Monads and other minute Infusoria, (pi. ix,
fig. 1, d). There are two jaws, armed at their ex-
tremities with four free teeth, the action of which is
very discernible, (pi. ix, fig. 1, c, and lign. 7, p. 56),
and it is amusing to watch the movements of these
dental organs when tearing the food. Ehrenberg men-
tions having seen a Stentor grasped by the tentacula ;
and I once witnessed a similar capture.

The Stephanoceros is ovo-viviparous ; that is, it
increases by eggs which are hatched ere they escape
from the sheath. A cluster of eggs may generally be
seen in the ovisac, and one or two advancing to ma-
turity, (pi. x).

Thj: Development of the Young in the Ste-
phanoceros.— As the progressive development of the
eggs and young of the Stephanoceros has not, I believe,
been made the subject of accurate observation, I shall
here introduce a few particulars which came under my
notice when investigating the organisation of this ani-
malcule in the spring and summer of 1843.

f2

68 THOUGHTS ON ANIMALCULES.

In several individuals one or two enlarged ova were
perceived, and these were situated on the side of the
body, (pi. X, e, e). The first perceptible change was the
gradual appearance of a dark nucleus in the largest
^&o' (pi. X, fig. 1, e\ which increased till it occupied
the whole of the cavity, except a narrow pellucid
border, (pi. xi, fig. 4, /). A slow semi-rotatory mo-
tion now became manifest in the inclosed embryo,
which in a few hours assumed a definite shape, appear-
ing like a soft, elongated, coiled up body, the head
being bent over the other extremity, (pi. xi, fig. 4, g).
The movements of the embryo soon became more
frequent and powerful, till at length the ^gg burst, and
the young animalcule escaped into the cavity of the
sheath, (pi. x, fig. 2, K), In this stage it was of an
elongated conical figure, having the largest extremity
fringed with cilia, and might readily have been mis-
taken for a Stentor, or similar polygastrian. The
young one, in the instance described, made its way to
the bottom of the sheath, from which, at the expiration
of three hours after its liberation from the ^gg^ it
escaped, and swam freely in the surrounding water*.

* In another individual, according to the observation of Mr. Lee,
the young one (from the uppermost egg, pi. x, fig. 1, c) escaped
from the upper extremity of the sheath, near the base of the rotatory
organ.

YOUNG OF THE STEPHANOCEROS. 69

Thirty hours after its liberation from the sheath of the
parent, the young Stephanoceros maintained the same
general appearance: but it had increased in size, the
cilia were larger, and their action more powerful ; and
a cluster of four (or five) sub-conical papillae was per-
ceptible within the body, (pi. xi, fig. 1, a) ; these were
probably the rudimentary rotatory organs. Eighty
hours after birth the young creature, when partially
contracted, appeared as in pi. xr, fig. 2, The five mam-
millated projections fringed with cilia, (four only are
shewn in this aspect), on the upper margin, are evi-
dently the rudiments of the tentacula. The position of
the stomach is indicated by the green colour of the food
that has been swallowed.

The development of this individual was traced no fur-
ther ; but in another, observed from its exclusion from
the egg to the eighty-fourth hour, the arms were more
produced, (pi. xi, fig. 3, a), and the digestive organs
very distinct, (pi. xi, fig. 3, b). In this example the
young one did not escape from the sheath : the parent
died about ten hours after the egg burst, and its body
soon decomposed. The young one continued to grow,
though inclosed in the sheath, till the eighty-fourth
hour, as shewn in pi. xi, fig. 3, when it expired. No
traces of a sheath or mantle were observable in any of
these specimens, nor was the red eye, described by M.

70 THOUGHTS ON ANIMALCULES.

Ehrenberg, detected in the young upon which the pre-
ceding observations were made.

I was unable to watch the further progress of the
young Stephanoceros. It is probable, that, after a short
term of freedom, it becomes fixed by the base, and
passes through successive stages of development to ma-
turity*.

* The observations described in the text were made while suffering
under a severe indisposition, which ultimately compelled me to abandon
the investigation. It was my intention to renew it under more favourable
circumstances, but, as this has hitherto been impracticable, this imperfect
notice is inserted, in the hope of inducing other observers to follow up the
inquiry.

THE WHEEL- ANIMALCULE . 71

XIII.

THE ROTIFER VULGARIS, OR COMMON WHEEL-
ANIMALCULE.

Plate XII.

In the water first examined may be noticed several
elongated leech-like animalcules, swimming about in
every direction, now winding their way among the
swarms of lesser beings, then fixing themselves by one
end, and protruding from the other extremity two cups
fringed with ciUa, which appear to whirl round and
round like a pair of wheels on their axes; or sud-
denly drawing in these organs, shrinking up the entire
body into a globular opaque mass, and leaving no
part of their internal organisation visible. These crea-
tures are the Wheel-animalcules, commonly so called,
and were the first species of the Rotifera that attracted
the attention of the early observers*.

* The Rotifer vulgaris was first figured and described by Leeuwen-
hoek in 1702 ; and more fully by Baker in 1744. See *' Employment
for the Microscope," pi. xi, p. 288, ed. 1785.

72 THOUGHTS ON ANIMALCULES.

The family to which they belong* comprises the Roti-
fers which are furnished with a pair of simple, nearly
circular, wheel-like rotators. The body is either cylin-
drical, fusiform (spindle-shaped), or vermiform, with-
out a case or sheath, but capable of contracting into a
globular mass by the involution or withdrawal of the
upper part of the body into the lower, somewhat after
the manner of a telescope. There are many species,
which are arranged in seven genera; most have eyes,
and discernible internal muscles. The species before
us (pi. xn) will suffice to afford a full illustration of
the organisation of this interesting group of animal-
cules ; and as it is abundant in every pool and stream,
in every phial containing water with decomposing vege-
tables, and may even be obtained from the dry sedi-
ment in leaden troughs, the reader, whose curiosity is
awakened by the following remarks, may readily pro-
cure specimens for examination.

The Common Wheel-animalcule, {^Rotifer vulgaris,
pi. XII, fig. 3), is from one-quarter to one-half of a line in
length: its body is of a whitish colour and fusiform shape,
that is, largest in the middle, and tapering towards the
ends, the tail part being the smallest. In the middle of

* Philodinea of Ehrenberg.

THE WHEEL-ANIMALCFLE. 73

the upper extremity of the body there is a protuberance,
or trunk, on which are two round red eyes placed on
ganglions, and a soft eye-speck. On each side this
trunk is a rotator, consisting of a semicircular cup
fringed with strong cilia: these organs are commonly
called the wheels. There is a respiratory tube, for the
free passage of water to the interior. The lower ex-
tremity of the body is furnished with a tail having six
points when expanded. The upper part of the aliment-
ary canal has a constriction or pharynx, which is sur-
rounded by four hemispherical muscular masses, placed
opposite to each other in a crucial position ; and these
are very manifest when in action. The pair of jaws,
with teeth, are of the type figured and described in
p. 5Q, and may be distinctly seen even in the em-
bryo. The nature and relative situation of these se-
veral parts will be best understood by reference to a
highly magnified view, by Ehrenberg, of a Rotifer
with the wheels displayed, and of which pi. xii, fig. 3,
is a reduced figure.

a, The trunk or proboscis on which the eyes are placed.

b, b, The rotatory organs, or wheels. The spiral course of the eddies in-
duced in the water by the action of their cilia is indicated by t^e-.
arrows . /^ ^' ^ ^ '^ -c\.

c, Tiie respiratory tube. /Ov'^ ^\^ \

fi!^/^ ^^-m^ \A€^^*

ujI library]^!}

74. THOUGHTS ON ANIMALCULES.

d, The jaws, armed with teeth.

e, The digestive organs coloured by a solution of carmine swallowed

by the animal. The direction of the currents to and from the
mouth, occasioned by the ciha around the entrance of the ali-
mentary canal, is shewn by the colour.

/, Four bundles of long internal muscles, by which the body is con-
tracted and extended.

g, An eg^ in the ovisac, containing an embryo, in which the eyes and
jaws are discernible.

A, The tail, or pedicle.

Of the organs above pointed out, the rotators are
those wliich always excite most surprise ; for, notwith-
standing what has been stated in explanation of their
true nature and action, the inexperienced observer will
find it difficult to divest himself of the idea that they
actually do move round like wheels, for they appear to
revolve continuously in one direction, because one set
of the vibratory movements of the rows of cilia is alone
perceptible, (see lign. 1, page 35). Each rotator has
from fifty to sixty fine cilia, which when vibrating form
twelve or fourteen groups: each cilium swings round
on its base, producing a motion like the rotation of the
human arm. When any colouring matter is introduced
into the water, the directions of the currents caused by
the cilia are very manifest. Those produced by the
rotators are gyratory ; those by the orifice of the mouth

THE WHEEL-ANIMALCULE. 75'

(indicated by the colour, pi. xii, fig. 3) are seen passing
down to the stomach ; and at the constriction, or neck,
the particles may be traced in a continuous line from
the mouth to the internal cavities. The motion of the
rotators is voluntary : it can be instantly arrested, and
the organs drawn out of sight, and again protruded, at
the will of the animal. When the wheels are drawn
in, while the body remains extended, and its trunk pro-
jecting, they appear like two flat semi-elliptical disks,
immediately above the jaws, (pi. xii, fig. 4, b, h).

An individual fixed by its tail, and having its body
much contracted, is shewn in pi. xii, fig. 7.

The Rotifer is oviparous, and eggs in progressive
stages of development may generally be seen within the
body. A young one just escaping from the ego^ is re-
presented in pi. XII, fig. 5. The increase of this species
is in a ratio almost incredible. Ehrenberg has ascer-
tained, by direct observation, that from a single indi-
vidual a million may be produced by the tenth day,
four millions by the eleventh, sixteen millions by the
eighteenth, and so on.

Such is the organisation of the Rotifer, as seen
under a good defining power. ' The mode of obtain-
ing these animalcules, and the varied appearances, and
diversified shapes and attitudes which they assume, are

76 THOUGHTS ON ANIMALCULES.

graphically described by Baker in the following ex-
tract : —

** If the water standing in lead gutters, or the slimy sediment it leaves
behind, has anything of a reddish colour, one may almost be certain of
finding the wheel-animals therein ; and if, in summer, when all the water
is dried up, and nothing but dust remains, that dust appears red, or of a
dark brown, one shall seldom fail, on putting it in water, to disclose multi-
tudes of minute reddish globules, which are, indeed, the animals them-
selves, and which will soon change their appearance ; for in the space of
half an hour a languid motion begins, the globule turns itself about,
lengthens by slow degrees, and becomes in the form of a transparent ca-
terpillar ; and appears lengthening out its body considerably at some
times, and contracting it as much at others. Its motion from place to
place is likewise then performed in the manner of such creatures : fixing
first its tail, and extending its whole body; then fastening its head, and
drawing up its tail to it, {see pi. xii, fig. 6) ; and so on, by which it gets
along pretty nimbly. But one shall often behold it changing this ap-
pearance in an instant, and assuming a form extremely different ; for its
snout being pulled somewhat inward, the front end becomes clubbed, and
immediately dividing, exhibits most surprisingly to view a couple of semi-
circular instruments before unseen, round the edges whereof many little
fibrillce (cilia) move themselves very briskly; sometimes with a kind of
rotation, and sometimes in a vibrating or trembling manner. An opening
or mouth also appears in the middle between these two semicircles.
When in this condition the animal is often seen to unfasten its tail, and
swim along with a great deal of swiftness, seemingly in pursuit of prey.
When the fore part of the creature first appears to open or divide, the in-
struments above described, which, when fully protruded, resemble a pair
of wheels having a quick rotation, coming then but a little way beyond
their tubular cases, and being in that condition like round pieces of paper
folded in the middle, or funnels whose sides are flattened almost together,
seem only like a couple of semicircular parts, about the edges whereof
what are seen afterwards like the teeth of wheels appear only as little

THE WHEEL-ANIMALCULE. 77

spicula, having a nimble and continual vibrating motion upwards and
downwards ; whereby the water becomes greatly agitated, and is brought
to the animal from several times the distance of its own length. As the
creature is capable of thrusting out these wheels, or drawing them in as
snails do their horns, the figure of them is different in their several degrees
of extension or contraction, or according to their position to the eye of
the observer*."

Resuscitation of the Infusoria. — Allusion has
already been made to the extraordinary tenacity of life
with which certain species of Infusoria are endowed, —
a phenomenon which did not escape the notice of the
early microscopists. That the eggs of the oviparous
kinds should be found capable of development for a
long period after their exclusion, would not excite
much surprise ; but that adult animals, possessing eyes,
muscles, nerves, organs of respiration, &c., should revive
after being dried up to dust, is a phenomenon so start-
ling, as to require the most satisfactory evidence, before
the possibility of such a resurrection could be admitted.
The statement, with some limitation, is however un-
questionably true ; for though it is not to be supposed
that any animal could revive if it were quite dried up,
yet it is certain that some species of the Infusoria will
remain in a dormant state for years, if buried in earth
or sand apparently dry. Some Kotifers were alter-

* Baker on the " Employment for the Microscope," pp. 269^ — 277.

78 THOUGHTS ON ANIMALCULES.

nateiy dried and rendered dormant, and then revived by
the addition of water, twelve times, appearing at each
successive resuscitation as active as at first*. Pro-
fessor Owen mentions having witnessed the revival of
an animalcule, (a species of Arctiscon), which had been
preserved in dry sand four years f.

* In this respect these animalcules resemble certain plants, whose te-
nacity of life is such, that they preserve their vitality, like seeds, for many
years. Mosses that had been dried for a century have revived after im-
mersion in water for a few hours.

f Hunterian Lectures for 1843, p. 40.

ANIMALCULES WITH SHELLS. 79

XIY.

ANIMALCULES WITH SHELLS.— THE BRACHIONUS, OR
SPINE-BEARING ANIMALCULE.

There is yet one kind of animalcule nnclescribed^
in the drops of water which have afforded us so many
interesting objects for investigation. This belongs to
the group of Rotifera which have their bodies pro-
tected by a firm sub-cylindrical shell, or carapace. Its
form is that of a vase, with a retractile forked pedicle
proceeding from the base. There are two species un-
der view, (pi. XII, figs. 1, 2).

I. The Pitcher-shaped Brachionus, {B. urceolaris,
pi. XII, fig. 1). — This species has a smooth shell, with
six short horn-like processes, or spines, on its front part,
and the lower end rounded. The body is white, from
one-sixth to one-eighth of a line in length, and fur-
nished on the upper part with a pair of lobed rotatory
organs, composed of five portions. The jaws have five
teeth at the free extremity, and may be regarded as
dental hammers divided into sharp spines, which crush

80 THOUGHTS ON ANIMALCULES.

the food upon the little block or anvil beneath, (pi. xii,
fig. 1, «, and p. 55, lign. 5, fig. 2). This creature has
one eye, which is quadrangular, a respiratory tube,
and trembling organs (hrancMcB) in the interior. It is
oviparous, and the eggs are attached to the body till
the young are hatched.

II. Baker's Brachionus, {B. Bakeri, pL xii, fig. 2).
— The shell of the other species is scabrous or rough,
with six unequal spines on the upper, and two very
long lateral ones on the lower end ; its jaws are shewn
in p. 55, fig. 2, a.

These minute beings aggregate together in number-
less myriads, so as to form whitish masses that float in
the water; after the death of the animals the shells
retain their form, and accumulate in layers at the
bottom of pools, lakes, &c.

Strata of Lime and Flint formed by Infusoria.
— In many families of the polygastric Infusoria, the
cases, or shells, consist either of lime, silex (flint), or
iron; and these retain their form and structure for un-
limited periods of time. From the inconceivable num-
bers of these sheU-animalcules which swarm in every
body of water, whether fresh or salt, and the immense
rapidity with which the species increase — by spon-

ANIMALCULES WITH SHELLS. 81

taneous fissuration, gemmation, and ova — extensive de-
posits or strata of their cases are constantly forming at
the bottom of lakes, rivers, and seas. Hence have
originated the layers of white calcareous earth common
in peat-bogs and morasses, — the tripoli, or polishing
slate of BiHn, consisting wholly of the siliceous cases of
animalcules, — and the bog-iron, composed of the ferru-
ginous shields of other forms of Polygastria. In short,
the extensive and important changes that have been
produced on the earth's surface by tliis agency, in the
earlier ages of the physical history of our planet, and
those of a like nature which are going on at the present
tmie, are in the highest degree interesting, and have but
lately become the subject of scientific investigation*.

* For an account of fossil animalcules, see ''Wonders of Geology,"
vol. ii, p. 798 ; " Medals of Creation," p. 215 ; and " Thoughts on a
Pebble," 7th edition. Vide Appendix,

82 THOUGHTS ON ANIMALCULES.

XV.

REFLECTIONS.

All the different kinds of animalcules contained in
the water placed under the microscope at the commence-
ment of our investigations having been examined, we
will remove the glass slide between which they are
confined, from the field of view; and now, a small
twig, and two or three minute leaves, with a fevf
flakes of mucu?, and a turbid condition of the water
from the presence of earthy particles, are the only
objects the eye can discern. All the diversified forms
of life that were sporting in the apparently wide waste
of water have vanished from our sight, and are as
though they were not; yet what a world of wonders,
what a marvellous display of Infinite Wisdom, are there
concealed! Within that narrow space, the microscope
has shewn us the mysterious principle of vitality em-
bodied in structures of which we had previously no
conception; and under conditions, which, if estimated
according to our . experience of the visible creation,
would appear incompatible with animal existence.

REFLECTIONS. 83

Were we to describe the facts that have come under
our notice to persons unacquainted with the optical
powers of the microscope, and tell them, that the seem-
ingly particles of earth in the water, are creatures of
various forms and structures, endowed with life, and
the capacity for its enjoyment; that those flakes of
mucus, are aggregated thousands of animals in the shape
of flowers, which increase, like plants, by buds and by
self-division; that some of these creatures are carni-
vorous, feeding on li\dng atoms more infinitesimal than
themselves ; that others are herbivorous, and nourished
by particles of decomposed vegetables, too minute to
be visible till accumulated in the internal organs of
the animalcules; that we selected some of these ani-
mals, and caused them to swallow carmine, and thus
imparted a red colour to their digestive organs, and
rendered their structure more obvious; that some are
free, and roam through the water at pleasure, — others
always sedentary, — others locomotive in youth, and
fixed to one spot in after-life ; that many have eyes, the
number and colour of which can be distinguished ;
that the difference in the relative magnitude of these
creatures is as great as that between a mouse and an
elephant ; that if the water in which these beings are
now immersed be allowed to evaporate, and the sedi-
ment become as dry as dust, and this be moistened

g2

«

84 THOUGHTS ON ANIMALCULES.

three or four years hence, many of the individuals at
this moment sporting through the water will be re-
suscitated and appear in full activity, although, had they
remained in their native element, the term of their ex-
istence would have extended but through a few days, —
thus realising one of the beautiful fictions of Arabian
story; would not this statement be deemed unworthy
of belief? would it not be regarded as improbable and
as extravagant, as the wildest chimeras of the imagina^
tion? And yet such a narrative would be but the
simple truth ; an unexaggerated, unadorned, matter-of-
fact summary, of the phenomena that have come under
our observation!

GENERAL REMARKS — CONCLUSION. 85

XVI.

GENERAL REMARKS ON THE INFUSORIA.—
CONCLUSION.

The Infusoria, like animals of higher organisation,
suffer and perish from sudden transitions of tem-
perature. They die in ice ; but, when the water first
congeals, each animalcule is surrounded by a moist
space, caused by the caloric liberated from its own
body*. A high temperature also destroys them: Vor-
ticellae often die under the microscope, if exhibited in
a hot room. Atmospheric air is as necessary for the
Infusoria, as for the warm-blooded animals. They are
killed by substances which affect the chemical composi-
tion of the water ; but the strongest poisons, if only in
mechanical suspension in the fluid, exert no influence
upon them. Fresh-water species instantly die if sea-
water be suddenly added, though the latter may swarm
with marine species ; but they survive if the mixture
be gradual, and many kinds inhabit brackish waters.

* Ehrenberg.

86 THOUGHTS ON ANIMALCULES.

Infusoria always appear in vegetable infusions, simply
because their ova or germs, being everywhere present,
find in such fluids a proper medium for their develop-
ment : hence the same kinds of infusions do not always
contain the same species of animalcules.

The atmosphere, which is always charged with in-
finitesimal particles of matter, both organic and inor-
ganic, wafts in every breeze immense quantities of the
sporules of plants*, and of the ova of animalcules.
The rapid increase of the Infusoria yields a never-
failing supply of their germs, and countless myriads are,
therefore, everywhere ready to burst into life, and go
through their assigned phases of development, when
placed under the conditions specially required by the
type of organisation to which they belong f.

* The sporules of some Fungi are so minute, and occur in such im-
mense numbers, that in a single individual (of Reticularia) more than ten
millions have been counted ; and they are so light and subtle, that they
are dispersed by the slightest agitation of the air, and even by evapora-
tion. The germs of these minute and simple forms of vegetation must,
therefore, always be present in the atmosphere.

t The Acari observed by Mr. Cross in the fluids of his galvanic ap-
paratus, cannot justly be regarded as offering a valid objection to this ex-
planation of the phenomenon. The appearance of these Acari, notwith-
standing the precautions employed to exclude or destroy their ova, in the
experiments of Mr. Cross and Mr. Weekes, does not present the same dif-
ficulty as the occurrence of Entozoa in the chambers of the human eye,
&c. See Appendix,

GENERAL REMARKS — CONCLUSION. 87

Though the influence of light is favourahle to infu-
sorial life, it does not appear to be absolutely necessary,
for many kinds of animalcules abound in the waters of
deep mines, which are always in impenetrable dark-
ness.

The ordinary duration of life in the Infusoria varies
from a few hours to several days, or even weeks : Ro-
tifera have been traced to the twenty-third day of their
existence. The death of these animals is generally
sudden; but, in some of the larger species, convulsive
struggles attend their dissolution. Shortly after death,
the soft parts rapidly decompose, and all traces of their
beautiful structures disappear: the species which are
furnished with earthy cases or shells, alone leave durable
vestiges of their existence *. •

The exceedingly small proportion of solid matter
that enters into the composition of these animals is re-
markable: from aggregated myriads and myriads, a
few atoms of dust alone remain! If it be supposed
that the bodies of the Infusoria are too minute to afford
any conclusive evidence on this point, it may be re- '
marked that the same phenomenon appears in certain

* The oceans that deposited those ancient sedimentary strata, in which
no traces of organic remains have been observed, (and are therefore called
by some geologists azoic), may, consequently, have been as densely peo-
pled with gelatinous organisms as the existing seas. See Appendix.

88 THOUGHTS ON ANIMALCULES.

other animal structures ; for example, in the Meduscs *,
many of which are of considerable bulk, some a yard
in diameter, and several pounds in weight, yet, after
death, their entire structure rapidly melts away, and
the only solid residuum is a thin film of membrane,
weighing but a few grains. The Physalia, so famihar
to voyagers by the common name of " Portuguese Man-
of-war f," and which skims along the surface of the sea
at pleasure, using its little crest as a sail, and often ap-
pearing in mimic fleets of thousands on the cahn expanse
of the ocean, consists only of an oblong bladder wrinkled
into a crest above, and sending off numerous attenuated
filaments from below. When taken out of the water,
it shrinks into a shapeless mass of jelly, and all its
substance evaporates, leaving a portion of earthy mat-
ter, relatively as inconsiderable as the residual dust of
the innumerable hosts of the Infusoria. Thus, in the
Medusas, as in the animalcules, all the functions of

* The Medusm are those elegant hyaline cup -shaped gelatinous ani-
mals, commonly known by the name of JeUy-fish, or Sea-blubber ; and
which, in the warm days of summer, may often be seen swarming in
thousands in the sea near our coasts, as at Southampton, Portsmouth,
&c. If one as large as a saucer is caught in the hand, and taken out of
the water, it instantly collapses into a small mass of jelly. '' A Medusa
weighing two pounds when first taken out of the sea, dried up to only
thirty grains of solid matter." — Professor Owen.

f Physalia pelagica ; see Vignette of title-page.

GENERAL REMARKS COXCLUSION. 89

-sitality are performed by structures, Avliose constituent
substance is scarcely more dense than the surrounding
element in which they dwell ; yet, in these frail tene-
ments, these mere definite aggregations of globules, life
is for awhile enshrined, and confers the power of re-
sistinof the chemical and mechanical effects of external
agents, of traversing the ocean, of piu-suing live prey,
of taking cognisance of danger, and of escaping from
its approach. But the moment that life departs, the
materials of which these organisms are composed, re-
leased from the dominion of the laws of vitality, are
resolved into fluid molecules, and rapidly pass into their
original elementary condition.

Final Effects. — With regard to the consideration
of the general purposes in the economy of Xature which
these in^dsible beings are destined to effect, I would
leave the intelligent reader to draw his own inferences
from what has been advanced; being con\dnced, that
no well-regulated mind can rise from the contemplation
of the marvels revealed by the microscope, without
being so deeply impressed with a sense of awe, of
humility, and of dependence, as to be secured from the
arrogance and presumption of attempting to interpret
the final purposes of the Eternal, even in the minutest
of HIS works.

90 THOUGHTS ON ANIMALCULES.

We may, indeed, take cognisance of some of the ob-
vious results of the operations of these living atoms ;
such, for example, as their influence in maintaining the
purity of the atmosphere and of the water, by the
conversion into their own structures of the particles
liberated by the decomposition of the larger animals
and vegetables ; and, in their turn, becoming the food of
other races, and thus affording the means of support to
creatures of a hio-her oro^knisation than themselves.
We see, too, that many species, after death, give rise
to the formation of earthy deposits at the bottoms of
lakes, rivers, and seas, which, in after-ages, may be-
come fertile tracts of country, and the sites of large
communities of mankind. But in this, as in all at-
tempts to interpret the mysterious designs of Pro-
vidence, we are but as " beings darkly wise ; " for it is
probable that many of the most serious maladies which
afflict humanity, are produced by peculiar states of in-
visible animalcular life. From some periodical and ex-
aggerated condition of development, particular species,
too minute for the most powerful microscope to descry,
may suddenly swarm in the air or in the waters,
and penetrating the internal vessels and organs, exert
an injurious influence of a specific character on the
lining membranes, and fluids, of the human frame.
And from this inscrutable agency may, possibly, ori-

GENERAL REMARKS CONCLUSION. 91

ginate the Cholera, Influenza, and other epidemic dis-

I NOW take farewell of the " Courteous Reader,"
who has indulgently accompanied me through this im-
perfect attempt to illustrate some of the important
subjects, involved in the microscopical investigation of
the Invisible World of Being. Amply will my labours
be rewarded, should they induce any of the young
and intelligent to enter upon a department of science
so replete with interest and instruction, and which is in
the hio^hest deo-ree calculated to exert the most bene-
ficial influence on the character, by leading the mind
from frivolous and unworthy pursuits, and exciting in
it those aspirations after truth and wisdom, which ele-
vate the soul above the petty passions and prejudices of
common life. "For who can contemplate the mar-
vellousness of God's works, and not think his best and

* For a full and able consideration of this most important and inter-
esting question, the reader is referred to " Medical Notes and Reflec-
tions," (by Henry Holland, M.D., &c.; London: 1839), chap, xxxiv,
" On the Hypothesis of Insect Life as a Cause of Disease." In the
opinions of this eminent medical philosopher on this subject I entirely
concur.

92 THOUGHTS OX A^'IAIALCULES.

most adoiing thoiiglits on the subject*?" And this
salutarv tendency it pos^sses in common with every
other branch of natural knowledge : for such is the
consmnmate perfection of <\ll the works of the Creator,
that whatever path of inquiry we may select for our
especial investigation, if followed in a right spirit, will
conduct us to the *• Foimt:iin of living waters," — to the
source of all Truth and Wisdom.

From niTriads take thv choice.

In all that lives a guide to God is gireii ;
Ever thou hear'st some Angel -guardian's voice,

"When Nature speaks of Heaven I f

Thus, in the impressive Language of Dr. Chalmers,
while the Telescope enables us to see a system in every
star, the ^Horoscope unfolds to us a world in every
atom. The one instructs us that this mighty globe,
with the whole burthen of its people and its coimtries,
is but a grain of sand in the vast field of immensity —
the other, that every atom may harbour the tribes and
famih'es of a busy population. The one shews us the
insignificance of the world we inhabit — the other re-
deems it from all its insignificance, for it tells us, that
in the leaves of every forest, in the flowers of eyery

* Leigh Hunt' 5 •• Yiat to the Zoological Gardens," 1S36.
t "The Guardian Angel." bv Sir E. B. Lvtton. Bart.

GENERAL REMARKS CONCLUSION. 93

garden, in the waters of every ri\n.ilet, there are worlds
teeming with life, and numberless as are the stars of the
firmament. The one suggests to us, that above and
beyond all that is visible to man, there may be regions
of creation wliich sweep immeasiu*ably along, and carry
the impress of the Ahnighty's hand to the remotest
scenes of the Universe — the other, that within and
beneath all that minuteness which the aided eye of man
is able to explore, there may be a world of invisible
beings ; and that could we draw aside the mysterious
veil which shrouds it from our senses, we might behold
a theatre of as many wonders as Astronomy can unfold;
a Universe within the compass of a point, so small as to
elude all the powers of the miscroscope, but where the
Almighty Ruler of all things finds room for the ex-
ercise of HIS attributes, where he can raise another me-
chanism of worlds, and fill and animate them all with
e^ddences of his glory !

APPENDIX

Analogy not Identity, see note to page 24.

Since this note was written, the Author of the " Ves-
tiges of the Natural History of Creation " has published
his " Explanations," as a sequel to the former work, in
which he states, that he never intended to aver that the
embryotic condition of the mammal is to be regarded as
identical with the permanent state of the Monad ; and
declares that he simply meant to express the resemblance,
or analogy, which the mammal bears, in the various
stages of its development, to certain inferior types of
animal organisation. " Perhaps," he observes, " no part
of the arguments for the development theory has been
more misapprehended, or misrepresented, than this. It
is continually said, that the embryo, at any of its parti-
wilar stages, is not in reality the animal represented by

96 APPENDIX.

" that stage. The truth is, no one ever pretended

that there was such an identity. It is only said, that there
is a resemblance in general character between the parti-
cular embryotic stage of being, and the mature con-
dition and form of the appropriate inferior animal*."
He then adverts to a special charge brought against
him, that he assumes " not only that the organic germs
of all creatures are alike, but that they are identical,"
which he states was not his meaning; but simply, " that
the embryos of all animals are not distinguishably dif-
ferent from each other f; " a proposition which but few
physiologists will be disposed to impugn. In justifi-
cation of myself, and of those who, like me, have mis-
apprehended, (not misrepresented), this author's opin-
ions, I quote the following passage, which may be
regarded as a concise expression of his theory.

" The idea, then, wliich I form of the progress of
organic life upon our earth — and the hypothesis is
applicable to all similar theatres of vital being — is, that
the simplest, and most primitive type, under a law to which
that of like-production is subordinate, gave birth to the
type next above it, that this again produced the next
higher, and so on to the very highest, the stages of ad-
vance being in all cases very small — namely from one

* Explanations, p. 108. f Ibid, p. 109.

APPENDIX. 97

species only to another; so that the phenomenon has
always been of a simple and modest character *." The
"Explanation" first quoted appears to me irreconci-
lable with this doctrine.

It would be foreign to the object of the present work,
to notice other opinions advanced in " The Vestiges,"
which bear upon some of the phenomena described in
the text ; but I would strongly recommend those who
are interested in the subject, to peruse with serious
attention, and unprejudiced mind, the " Explanations "
of this able anonymous author. I venture to offer
one word of caution, namely, that the arguments in
proof of the development theory, derived from fossil
organic remains, should not, in the present state of our
knowledge of the ancient inhabitants of the globe, be
regarded as conclusive. The evidence hitherto ob-
tained is insufficient to warrant the assertion, that " the
remains and traces of plants and animals found in the
succession of strata, show that the earth gradually be-
came the theatre of organic being, — simple forms appear-
ing first, and more complicated afterwards. A time when
there was no life is first seen; we then see life begin, and
go on,^'' &c. t The hasty generalisationson this topic,
in which many eminent geologists and palaeontologists

* Vestiges of the Natural History of Creation, 4th ed., p. 231.
t Explanations, p. 30.

H

98 APPENDIX.

have indulged, are much to be regretted, for they have
been assumed from insufficient data, and can only be
regarded as shifting hypotheses, to be modified, con-
firmed, or rejected, with the progress of discovery.
The ingenious manner in which the shrewd author
of " The Vestiges " has brought these speculations to
bear in support of his own hypotheses, will, I trust,
prove a salutary caution.

Organic Cells, p. 25. — In examining animal struc-
tures with the highest powers of the microscope, a
primogenial nucleated cell suddenly terminates our ana-
lysis, and forms the extreme limit of our power of in-
vestigation. Cells, therefore, appear to constitute the
minute and marvellous laboratory, in which the essen-
tial changes of organic life are performed; all the
various processes of vitality being effected by the agency
of cells, not distinguishable from each other by any
appreciable physical characters. Thus, one system of
cells secretes the bile, another the adipose substance,
another the nervous matter, and so forth; but how
these special products are formed by cells, apparently
of similar organisation, from the same nutrient fluids,
we know not. Whether the special endowment be-
longing to the system of cells of a particular organ,
depends on the intimate structure of the walls or tissue

APPENDIX. 99

of such cells, and this structure be so attenuated
and infinitesimal as to elude observation ; or whe-
ther it results from the transmission of some peculiar
modification of that mysterious vital force we term
nervous influence, are questions, to which, in the pre-
sent state of our knowledge, no satisfactory reply can
be given.

Localities of Fresh-water Infusoria, p. 28. — The fol-
lowing remarks on the situations in which the differ-
ent kinds of fresh-water animalcules may generally be
found, offer some useful suggestions to the inexpe-
rienced observer*.

In stagnant and putrid water, the ordinary forms of
Infusoria only are met with ; but in clear pools and
streams the most elegant species abound, and are often
found clustering around, or attached to the stems and
under-sides of the leaves of aquatic plants. Twigs,
leaves, &c., that are beneath the surface of the water,
particularly such as appear to be coated with slime,
will be found to harbour myriads of Vorticellas, Roti-
fers, &c. The yellow, green, blue, reddish, and brown
mucus floating on the surface, generally swarms with
interesting and beautiful species.

* Translated from Mandl's ** Traite pratique du Microscope."

h2

100 APPENDIX.

In collecting Infusoria, several clear phials, with
wide mouths, and cork stoppers, are necessary; and
a good pocket magnifier, with three lenses of dif-
ferent powers, will be required, to examine objects on
the spot, that useless or uninteresting specimens may-
be rejected. The phials should be filled with fresh
water nearly to the top; and small portions of the
aquatic plants, to which animalcules are attached, should
be collected ; but the phials must not be crowded with
leaves or stems. The corks must be removed as soon
as possible, for if the air is long excluded, many of the
animalcules will perish. In winter. Infusoria may often
be found around the Confervae under the frozen water.
In searching for animalcules in a muddy pond, it is advi-
sable that some of the water should be poured through
a piece of linen, or silk, to get rid of the extraneous
matter; for the Infusoria will pass through the filter,
and thus be more easily detected.

To procure the Infusoria from vegetable infusions, it
is only necessary to put fruit, hay, grass, or other
vegetable matter, into water, and expose it in open
vessels for a few days : a pellicle or film of mucus will
soon appear on the surface, and be found to consist al-
most entirely of animalcules.

To select specimens for examination, a small quantity
of water from one of the phials should be poured into a

APPENDIX. 101

watcli-glass placed on a card, or board, half of which is
black, and the other white; by this means the dark-
coloured animalcules wiU easily be recognised on the
white surface, and the transparent ones, on the black
ground. The minutest kinds often congregate around
the margin of the water in the glass.

Particular species may be selected by means of
a glass tube, and placed on a glass slide under the
microscope : powers magnifying from 300 to 400 will
be required for their proper inspection. The larger
and isolated forms, as the Stephanoceros, Limnias, Meli-
certa, &c., should be taken up with a feather or camel-
hair pencil: by a little practice, an individual may
easily be isolated and placed in a live-box, or between
two slips of glass. If the animalcules are not at-
tached to any vegetable substance, a small fragment
of a leaf should be interposed between the two
pieces of glass, that they may not be compressed and
destroyed.

Fossil Infusoria, p. 81. — That those infinitesimal forms
of existence, whose presence in our lakes, rivers, and
seas, can only be made manifest by the aid of the
microscope, should be detected in a fossil state, and
their aggregated skeletons or shields constitute entire
chains of hiUs, and the subsoil of extensive tracts of

] 02 APPENDIX.

country, is one of the most interesting discoveries of
modern Geology*.

The peat-bogs and swamps, both of modern and an-
cient date, often contain masses of a white, marly,
siliceous paste, wholly made up of the shells of Infu-
soria. Such is the white earthy substance found in the
peat-bogs of Ireland, Yorkshire, &c. The polishing-
slate of Bilin, in Prussia, forms a series of strata four-
teen feet thick, and is entirely composed of the siliceous
shields of Infusoria, of such extreme minuteness, that a
cubic inch of the stone contains forty-one thousand mil-
lions of distinct organisms !

In Virginia there are extensive beds of siliceous
marls, that are largely composed of the durable shields
of various kinds of marine animalcules. When a
few grains of this earth are properly prepared for
the microscope, numerous species of the most ex-
quisite forms are visible: in fact, the merest stain
left by the evaporation of a drop of water in which
some of the marl has been mixed, teems with beau-
tiful infusorial structures. This aggregation of the
fossil remains of beings, so minute, as to be invisible
to the naked eye, forms strata several yards in thick-

* This subject is treated at length in my " Medals of Creation,'
chap. vii.

APPENDIX, 103

ness. ' The towns of Richmond and Petersburgh, in
Virginia, are built upon this infusorial sandstone.

All the species of animalcules found in the Richmond
earth are marine ; and many of them belong to genera,
(if not to species), that inhabit the present seas, al-
though the position of these American strata proves
that they are referable to a very remote geological
epoch. Some of the prevalent Richmond forms, (the
Coscinodisci, or sieve-like disks), live in the British
Channel ; and my son, (Mr. Reginald Mantell), de-
tected in the mud of the quicksands along the shore at
Brighton, the shields of numerous recent Coscinodisci,
associated with fossil Infusoria washed out of the neigh-
bouring chalk-cliffs.

Another interesting discovery in connexion with this
subject may here be noticed. The common scallops, as
well as other moUusks, feed on Infusoria, and their
stomachs often contain thousands of shells, which,
being sUiceous, have resisted the process of digestion.
A glass slide mounted with a few particles of the undi-
gested contents of the stomach of a scallop, presents an
assemblage of infusorial shells, apparently identical with
those forming the Richmond earth*. So close, indeed, is
the analogy, not only of the individual shields, but even

* Mr. Hamlin Lee first noticed this interesting fact.

104 APPENDIX.

of their collocation, that it would be difficult for an ex-
perienced observer to distinguish slides, mounted with
the respective organisms, from each other; although
one group is from deposits of unfathomable antiquity,
and the other from the British Channel*.

The guano from Ichaboe, when long digested in di-
lute hydrochloric acid, leaves a siliceous residuum, which
consists of shields of Coscinodisci and other marine
Infusoria, of exquisite beauty.

Entozoa, or internal Parasitical Animals'], note to p.
86. — Though the hypothesis enunciated in the text,
which is founded on the doctrine of the celebrated Her-
yey — "omwe vivum ah ovo^^ — satisfactorily accounts for
the presence of Infusoria and other minute organisms
under ordinary circumstances, and is sanctioned by
direct observation to an almost unlimited extent, yet
there are peculiar states and conditions under which
animalcular life becomes developed, that are inexpli-
cable in this view of the subject ; and are, indeed, in-
comprehensible in the present state of our knowledge.
Such, for instance, as the occurrence of the various

* See my " Notes of a Microscopical Examination of Chalk and
Flint," in the Annals of Natural History, August, 1845.

t The Entozoa live in the internal parts of other animals ; and some
of the Entozoa are themselves infested with parasites.

APPENDIX. 105

kinds of Entozoa, many of which are restricted to parti-
cular organs of particular species of animals, and are
themselves the theatre of existence to other parasitical
beings !

Here, as Dr. Holland emphatically remarks*, we
approach to speculations, which, though founded on the
most minute forms of existence, have yet a vastness in
their obscurity, and in the results to which their solu-
tion would lead. Hence the questions arise, whether
animal or vegetable life, (for the inquiry equally regards
both), is in any case produced, except from the eggs or
germs of prior individuals of the same species ? whether
there may not be matter so constituted, as to be capable,
from the influence of some unknown law, of assuming
an organic character, and giving rise to particular
species of living beings, whenever the conditions suit-
able to the development and continuance of such organ-
isms are present? The theory of the origination of
living beings from inorganic elements, or, to use the
expression of the author of the " Vestiges," " of organic
creation hy law,^^ offers a solution to these difficult
problems; but no certain evidence has yet been ob-
tained to substantiate, or even sanction this hypothesis.

* Medical Notes and Reflections, p. 579.

106 APPENDIX.

This, in fact, is the serious, and only legitimate ob-
jection to a doctrine, which would explain many obscure
physiological phenomena, and bring the laws of vitality
into harmony with those which preside over the in-
organic kingdom of nature.

Azoic sedimentary Strata, note to p. 87. — From the
absence of all traces of animal and vegetable structures,
or more properly from the non-discovery of organic
remains, in the most ancient sedimentary strata, (those,
for example, below the Lower Silurian), some eminent
geologists infer that the deposition of these rocks was
antecedent to the creation of organic beings. This
inference appears to me most unphilosophical; for nega-
tive evidence, as it is termed, in the present state of
geological science, is in fact no evidence at all, as we
are still but imperfectly acquainted with the entire
system of organic nature in any one of the grand epochs
of Geology.

If we endeavour to trace the order of succession of
animal and vegetable organisation upon our planet, as
demonstrated by fossil remains, we are at once impressed
with the insufficiency of the data hitherto obtained, to
present us with a true picture of the full development
of organic life, as it existed in the earlier ag6s of the

APPENDIX. 107

earth's physical history*. How little do we know of
the Faunas and Floras even of those countries whose
spoils now constitute the dry land of the south-east of
England ! For example, no traces of Infusoria have been
detected in the Wealden strata, though diligent search
has been made by competent observers; yet no naturalist
will doubt that the mollusks and crustaceans, ( Cyprides),
found in those fluviatile deposits, fed upon fresh- water
animalcules, like their recent congenors; and it is pro-
bable, that, sooner or later, fossil Infusoria will be dis-
covered in the Wealden formation. The following remark
of Mr. Lyell is in accordance with the opinions above
expressed: — "It is too common a fallacy to fix the era of
the first creation of each tribe of plants or animals,
and even of animate beings in general, at the precise
point where our present retrospective knowledge happens
to stop t-"

A similar fallacy pervades the ingenious speculations
as to the relative depths in the ocean in which certain
strata were originally deposited, as indicated by the
presence or absence of particular species of shells; the
geographical and vertical range of their presumed living
analogues being taken as the data upon which these

* See '' The Medals of Creation, Vol. II, p. 872.
f Lyell' s Travels in North America.

108 APPENDIX.

generalisations are based. Thus, in the absence of all
positive evidence, a considerable portion of the cre-
taceous formation is stated to have been formed by
deposits "not far from the zero of animal life^;^'' and this
startling assertion is deemed by the author of the " Ves-
tiges," f "a satisfactory explanation of the non-appear-
ance of forms intermediate to the reptiles and mammals
in the chalk "!

Change of Climate, note to p. 26. — To avoid misap-
prehension, I would observe, that it is not intended to
deny or imdervalue the great benefits to be derived
from a change of climate, and the selection of a suitable
air and residence, for persons labouring under pulmonary
affections, and which are so forcibly pointed out in the
classic work of that eminent physician Sir James Clark;
but simply to denounce the too common practice, of
neglecting the most effectual remedial measures in those
states of disease, which climatorial influence alone can
neither remove nor ameliorate.

* Ansted's Geology,
t Explanations, a Sequel to the Vestiges, p. 93.

APPENDIX. 109

MISCELLANEOUS NOTES.

Bacillaria.— Should tliis Volume meet the eye of
the naturalist, the omission of any notice of the nu-
merous family of Bacillaria, (the Stick-like Animal-
cules of Ehrenberg), some species of which are gene-
rally present in water containing Infusoria, will require
explanation. It has arisen from the opinion that not-
withstanding the observations of M. Ehrenberg, the
animal nature of these organisms is very doubtful. I
am more inclined, with the botanists, to refer them
to the vegetable kingdom, and consider them as Algae,
belonging to the order Desmidiacecs, than as being in
any way related to the Infusoria.

Microscopes. — -The microscope employed in the in-
vestigations described in the text, was an achromatic
made by Mr. Boss, the eminent optician, (Featherstone

110 APPENDIX.

Buildings, Holborn, London). Mr. Ross's Educational
Microscope is a cheap and good instrument.

Excellent microscopes are made by Mr. Smith, (Iron-
monger Row, St. Luke's), Messrs. Powell & Lealand,
(Clarendon Street, Somers Town), and other well-
known London opticians.

Mr. Andrew Pritchard, (162, Fleet Street), who by
his various works has greatly promoted the taste for
microscopic investigations in this country, has furnished
many of my friends with an excellent microscope, of
sufficient power for every useful purpose, at the price of
from 71 Is. to 12/. 12*.

Mr, Pritchard has published an abstract of Ehren-
berg's Classification of Infusoria, with numerous figures,
under the name of " A History of Infusoria, living and
fossil," 1 vol. 8vo. Whittaker & Co., London, 1845 ; it
may be had with the plates either uncoloured or coloured,
(price 305.); the latter is well worth the additional
price. This work is the best in the English language,
for those who desire to follow up this interesting de-
partment of natural history.

There is a cheap French work on the microscope,
which will be found an excellent manual; it is entitled
" Traite pratiqve du Microscope, et ile son Emploi dans
V Etude des Corps organises, par le Docteur L. Mandl ;
suivi de Recherches sur V Organisation des Animaux

APPENDIX. Ill

Infusoires, par D. C. G. Ehrenberg; accompagne de
14 Planches J^ A Paris, 1839 : Bailliere, Regent Street,
London; price 85. This volume explains the mecha-
nism of the best modern microscopes, describes the various
modes of examining organic and inorganic subjects, and
presents an abstract of Ehrenberg's arrangement and
nomenclature of Infusoria. The plates contain 188 un-
coloured figures of the principal genera; which, though
of very coarse execution, will enable the observer to
identify the usual forms.

Mr. Dancer (13, Cross Street, King Street, Man-
chester) supplies a good microscope and the necessary
apparatus, in a neat mahogany box, with the highest
power magnifying 250 linear, at 11. 155. ; and with an
additional power magnifying 400 linear, lOZ. I85. I am
informed by Mr. Williamson, surgeon, Manchester, (a
gentleman well known for his important microscopical
investigations), that these instruments are very excellent,
and are the only ones he has employed.

Objects for the Microscope. — My country readers
may find it useful to be informed that objects for ex-
amination, both recent and fossil, may be obtained of
Mr. Topping, 1, York Place, Pentonville, London.
The usual price is Is. 6d. a slide ; but very rare objects.,
and such as are difficult to prepare, are from 2^. to 3^.

112 APPENDIX.

each. Glass tubes, live-boxes, and all the usual re-
quirements for microscopical investigation, may also be
obtained of Mr. Topping.

Mr. Darker, Paradise Row, Lambeth, is an excellent
artist, and well known for the neatness and finish of
his microscopical preparations and instruments, objects
for the polarization of light, &c.

Instructions for the preparation of fossil teeth, bones,
wood, &c., for microscopical examination, are given in
my "Medals of Creation; or. First Lessons in the
Study of Organic Remains."

Drawings of microscopic subjects. — By means of
a Camera Lucida attached to the microscope, a person
accustomed to draw will be able, after a little practice,
to delineate any object. To those who require an artist
either to make the original drawing, or to transfer it to
stone, zinc, &c., I would recommend Mr. Lens Aldous,
(4, New Street, Surrey Zoological Gardens, London),
as an experienced and able artist ; the exquisite plates
in Professor Owen's " Odontography'''' justify this com-
mendation ; the lithotints of the present volume are
specimens of his skill in this branch of art.

DESCRIPTION

PLATES

114

DESCEIPTION OF PLATE I.

THE HYDR^, OR FRESH-WATER POLYPES.
( Page 12. )

\_The Figures are slightly enlarged, for the sake of distinctness. 1

Fig. 1. Three Green Polypes, {Hydra viridis), attached to the stem of an
aquatic plant, p. 13.
a, The base or pedicle of the Hydra.
h, The mouth and arms.
Fig. 2. The Common Fresh-water Polype, (/Zy^Zra vulgaris), partly con-
tracted, and the stomach distended with food.
Fig. 3. The Long-armed Polype, {Hydra fused), with the arms extended
in search of food, p. 15.

c, A small red worm seized by one of the tentacula, or arms.

d. An aquatic insect, caught by another of the arms.

Fig. 4. The Hydra vulgaris attached to a twig : two young ones are

seen sprouting from the sides of the body, p. 14.
Fig. 5. The Hydra vulgaris in a contracted state.
Fig, 6. The Hydra fusca moving to and fro in the water in quest of

prey, p. 15.
Fig. 7. The Hydra fusca, with a worm, which it has partly swallowed ;

the extremities hanging out of the mouth, and secured by

the tentacula of the Polype, p. 15.

m

^.>4^

fP^

,T

Lens A)d»u3 Hthotmi

The Hydrae or Fresh Watw Polypes.

DESCRIPTION OF PLATE I. 115

Fig. 8. A longitudinal section of a Polype magnified, p. 15.

e, The cellular structure of the substance of the body.

/, The arms, or tentacula, shewn to be hollow prolongations

from the body.
g, The lining, or villous coat, of the stomach or digestive sac.
Fig. 9. The Hydra viridis, in the various attitudes it assumes when
moving from place to place, p. 14.
fl. The base, or pedicle.
J, The mouth and arms.

i2

116

LESCEIPTION OF PLATE 11.

THE MONADS AND STENTORS.

( Page 36. )

[All the Figures highly magnified.'\

Fig. 1. The Vibriones, or Trembling Animalcules. Several groups of
these Monads united in filiform chains : the undulated form
is assumed when these creatures are moving through the
water ; p. 41.

Fig. 2. The Tablet Monads, (Gonium pectorale); a group of sixteen in-
dividuals ; p. 38.

Fig. 2a. Two detached animalcules of the Breastplate Gonium, {Goninm
pectorale), more highly magnified.

Fig. 3. A group of four individuals of the Cloaked Monad, {Chlamido-
monas), produced by the spontaneous division of two indi-
viduals ; p. 37.

Fig. 4. A group of the Terminal Monad, (Monas termo).

Fig. 5. The Viviparous Monad, (Monas vivipara); p. 37.

Fig. 6. A group of the Red Monad, (Monas vinosa, so named from its
colour) ; the originals extremely minute.

Fig. 7. Two detached individuals of the Dust Chlamidomonas, (C. pul-
visculus); p. 37.

a, A single animalcule.

b, A Monad, in which the fissuration into two individuals has

commenced.

PI u

%^' ^

m^

M^^

Lens AJd-ous "hftiotvat

Monads aiid bieuLO!

DESCRIPTION OF PLATE II. 117

iG. 8. The Monas vivipara; an individual dividing into two; p. 37.

Fig. 9. The Revolving Monads, {Volvox globator); representing the
young escaping from the parent globe; p. 39.

Fig. 10. The Globe Volvox, {V. glohator)-, five young globular clusters
are contained within the outer or parent globe; p. 40.

Fig. 11. A single Monad of the Globe Volvox, very highly magnified ;
shewing the red eye-speck, the horns, the six connecting
lateral filaments, and the globular sacs; p. 39.

Fig, 12. Part of the globe of a Volvoae, magnified 500 linear; shewing
in the centre several groups of the Monads produced by
self- division ; p. 39.

Fig. 13. The Blue Stentor, (Stentor ccBruleus); p. 44.

a. The lateral crest, only partially seen in this position.

Fig. 14. A group of the Multi-shaped Stentor, {Stentor polymorphus);
p. 43.

Fig. 15 Shews a Stentor polymorphus in a form it often assumes when
floating through the water.

Fig. 16. A twig, covered with thousands of the Stentor polymorphus,
which appear to the naked eye like an incrustation of
green jelljr ; from the lake in the garden of Dulwich Col-
lege. This twig was from a branch three feet long, that had
fallen into the water, and was literally covered with innu-
merable aggregations of these Infusoria; p. 44.

118

DESCRIPTION OF PLATE HI.

THE VORTICELL^, OR BELL-SHAPED ANIMALCULES.
( Page 42. )

[All the Figures highly magnified.']

Fig. 1. The Arborescent Vorticella, {Carchesium polypinum), seen with

a low power. This group is formed by the spontaneous

fissuration being incomplete. See p. 48.

a, fl, Two individuals thrown off from the parent stem. An

enlarged view of one of these liberated animalcules is

shewn in fig. 4.

Fig. 2. One of the Vorticellse of fig. 1, highly magnified, shewing the
process of fissuration, by which one animalcule becomes two
individuals, each supported by a stem, and continuing at-
tached to the parent trunk ; p. 48.

Fip. 3. A group of Vorticellse, {Vorticella nebulifera), representing the
animalcules in various attitudes. Some are single, others
have divided into two ; some are extended, others have
their pedicles or stems more or less spirally contracted ; in
several instances the pedicles are destitute of bodies, the
animalcules having broken the connexion, and swam off;
p. 44.

Fig. 4. An animalcule of the group fig. 3, separated from the pedicle,
and having a row of cilia at the base; p. 47.

TIJR.

,v^^

1

1

*

k' *'

c

1

1
1

: :

,.#

C

J'

J

1

♦ ^ •

•

iv

.

'^"^ ^.^orticdlae or Bdl-sliapedAiniiLalcLiles

TVaiaraZ Si/lt z^ 4 ofau Line-. )

DESCRIPTION OF PLATE III. 119

Ftg. 5. The appearance to the naked eye of thousands of Vorticellse sur-
rounding the roots of two or three leaves of the Lemna ;
p. 42.

Fig, 6. A group of three Vorticellae, {Vorticella camjjanulata), mxsinoxis
states of contraction. A foreshortened view of the body is
shewn in the left-hand figure.

These animalcules are represented as fed with carmine ; with the ex-
ception of the Vorticellae in the upper part of th€ group fig. 3, which are
shewn of their natural appearance, their globular sacs being filled with
green matter.

120

DESCRIPTION OF PLATE W.

THE LIMNiAS, OR WATER-NYMPH,
( Page 58. )

[The Figures highly magnified.l

A group of eight individuals of the Hornwort Limnias, (Limnias cera-
tophylli), is here represented.

a, The animalcule entirely withdrawn into its tubular case.

b, The rotatory organs and cilia fully expanded in the parent ani-

malcule, within the sheath of which several eggs, (e, e,), may
be distinguished.

The animalcules are represented in different states of protrusion and
expansion from their tubular cases, or sheaths.

PI IV

^h^• LirijQias or Water 2\vniph

122

DESCRIPTION OF PLATE V.

THE MELICERTA, OR HONEY FLOSCULARIA.
( Page 59. )

{The Figures highly magnified.']

Fig. 1. The jaws and teeth of the Melicerta, very highly magnified,
(copied from Ehrenberg).

Fig. 2. A very young individual of the Beaded Melicerta, {M. ring em),
with two rows of corpuscles on the sheath, coloured by
carmine.

Fig. 3. The same animalcule in an earlier stage, with only one ring of
corpuscles on the sheath, or case.

Fig. 4. The adult Melicerta, with the rotatory organs fully expanded.

Fig. 5. The individual figured above, (figs. 2 and 3), in a more advanced
stage. The granular case consists of several rows of corpus-
cles, of which the two upper and lower rows are coloured
by carmine ; p. 60.

Fig. 6. An adult Melicerta; the body but partially protrud§d.

}'i V

/^- ^^

. iMii^a

i^~^^^, ''<^r^^

.he readed Ivlelicert

7i'ilti/J<xl ,^VlC i of 4C hvii

124

DESCEIPTION OF PLATE VI.

THE FLOSCULARIA, OR FLOWER-SHAPED ANIMALCULE.
( Page 6L )

[The Figures highly magnified. 1

Two individuals of the Elegant Floscularia, {Floscularia ornata), at-
tached to a stem of Chara ; the natural size is from -^ to ^ of a line.
Fig. 1. The animalcule protruded from its transparent case.

a, The jaws and teeth.

b, The stomach, containing Monads, Naviculse, and other small

polygastrian animalcules.
Fig. 2. A Floscularia, with the body wholly withdrawn into its case, the
termination of the long cilia alone appearing externally,
e, An e^g in the ovisac, containing a young one, in which
the red eyes may be discerned.

l*^

()

126

DESCEIPTION OF PLATE VII.

THE FLOSCULARIA ORNATA, OR ELEGANT
FLOSCULARIA.

( Page 61. )

In this example, the upper part of tne body of the animalcule, with the
rotatory organs, is protruded, and bending over the margin of the tube, or
sheath.

Three ova, in various stages of development, are seen within the case.

*\

I

I

128

DESCRIPTION OF PLATE YIIL

THE FLOSCULARIA PROBOSCIDEA, OR HORNED
FLOSCULARIA.

( Page 61. )

This species of Flower-shaped Animalcule has a ciliated proboscis, or
horn, (fl), surrounded by the rotatory organs, which are furnished with
short cilia. In this example the animal is fully extended ; the jaws are
distinctly seen ; the stomach filled with food, and one egg within the
sheath, are also visible.

130

DESCRIPTION OF PLATE IX.

THE STEPHANOCEROS, OR CROWNED
WHEEL-ANIMALCULE.

( Page 63. )

Two individuals of the Stephanoceros, {Stephanoceros Ehrenbergi),
are here represented attached to the stem of an aquatic plant.

Fig. 1. The animalcule fully protruded from its transparent sheath.
The rotatory organs, composed of five long tentacula fur-
nished with rows of short verticillate cilia, are extended in
the form of an elongated dome, the extremities meeting in
the centre.
a, Small oval bodies, supposed to be nei-vous centres, {ganglia) '

to supply the tentacula, p. 66.
h, The trembling organs, p. 66.

c, The jaws and teeth, p. 67.

d, The stomach.

c, The transparent case.
Fig. 2. The animal shrunk down towards the bottom of the case. The
upper part of the arms, pressed together in an obtuse elon-
gated cone, alone appears above the margin of the sheath,
p. 65.

/

ft

k2

132

DESCRIPTION OF PLATE X,

DEVELOPMENT OF THE OVA OF THE
STEPHANOCEROS.

( Page 67. )

Two indivividuals of the S. Ehrenbergi, shewing the development of
the ova.

Fig. 1. In this example an Q^g, (e), is seen in an advanced steige of de-^
velopment. The same ovum, two hours latei*, is shewn in
pi. XI, fig. 4, e; p. 68.

Fig. 2. Two eggs, (e, e), almost arrived at maturity, wer'e observed in the
Stephanoceros here figured. The lowermost one, (e*), wa&
watched till it burst, and the young animal escaped into the
parent sheath. It is shewn at h, making its way towards
tibe bottom, from which it ultimately escaped; p. 68.

Aldoiis kthotaLt

'■ ■ ' '"^'"iopriiaii UL iiie Ova lu iLic ^ic^iidUv

134

DESCRIPTION OF PLATE XI.

ILLUSTRATION OF THE DEVELOPMENT OF THE YOUNG
STEPHANOCEROS.

( Page 67. )

Fig. 1. The young animalcule, represented in pi. x, (fig. 2, h), as it ap-
peared thirty hours after its exclusion from the parent
sheath; p. 69.
a, Apparently the rudiments of the arms.
c, The cilia.
Fig. 2. The same individual eighty hours after exclusion ; the body ap-
pears much shortened from being somewhat contracted ;
p. 69.

a, The arms, five in number ; but only four are seen in this

view.

b, The stomach.

Fig. 3. A young Stephanoceros eighty-four hours after exclusion from
the e^^, but still retained within the sheath of the parent,
which perished ; p. 69*.
a, The arms, or tentacula.
h, The jaws.

*, Remains of the sheath of the parent.
Fig. 4. A sketch of part of the body of a Stephanoceros, to shew the de-
velopment of the egg ; p. 68.

* The above three figures were drawn with the camera lucida; the magnifying
power employed was the i-inch object glass of Ross's Achromatic.

5j!J

'lie Deveiwu

/•

v

ii

DESCRIPTION OF PLATE XI. 135

s, The sheath.

e, The egg.

/, The pellucid zone, around the embryo.

gf, The nucleus, having a constant semi-rotatory motion.

h, h, Part of the body of the parent animalcule.
This egg was watched by Mr. Lee tiU it burst, and the young was
excluded into the sheath of the parent ; from whence, in four hours, it
escaped, from the upper part of the case ; p. 68.

136

DESCRIPTION or PLATE XII.

ROTIFERS, OR WHEEL-ANIMALCULES.
( Page 71. )

Fig. 1. The Pitcher-shaped Brachionus, {B. ureeolaris)-, p. 79.

a, The jaws.

b, The carapace, or shell.

c, The pair of rotators.

d, The pedicle, or tail.

e, e, Ova, or eggs, attached to the body of the animalcule.
Fig. la. The jaws and teeth of fig. 1, highly magnified.

Fig. 2. Baker's Brachionus, (5. Bakeri) ; p. 89 ; the letters have the

same references as above.
Fig. 2a. The jaws and teeth of Baker's Brachionus.
Fig. 3. The Common Wheel -animalcule, {Rotifer vulgaris) ; reduced

from Ehrenberg's figure ; p. 73.

a, The trunk or proboscis, on which the two red eyes are
placed.

b, b, The rotators, or wheels. The course of the eddies m-

duced by the cilia is denoted by the arrows.
e, The respiratory tube.

d, The masticatory apparatus, or jaws and teeth.

e, e, The alimentary canal coloured by carmine. The dii-ec-
tion of the currents occasioned by the vibration of the cilia
of the mouth is shewn by the coloured arrows.

nxii

Tke Plot iters or Wh^el-AnimaLcules

A

DESCRIPTION OF PLATE XII. 137

/, Four bundles of long internal muscles.

g, Eggs in the ovisac ; the red eyes of one of the young are

very manifest.
h, The tail, or pedicle.
Fig. 4. A Rotifer with the proboscis, (a), extended, and the wheels, {Jb, b),

withdrawn, appearing like two hemispherical radiated disks.

d, The jaws and teeth.

e. The stomach.
h, The pedicle.

Fig. 5. A young Rotifer just escaped from the egg ; p. 75.

Fig. 6. A Rotifer with the body bent over arch-wise, in the act of
moving along the surface of the stem of a plant. Loco-
motion is performed as in the Hydrse (see pi. i, fig. 9);
p. 76.

Fig. 7. A Wheel-aniiiuilcule with the body much shrunk down, and the
wheels drawn in ; a few cilia only appearing at the mouth,

(«); p. 76.

d, The masticatory apparatus.

g, The red eyes of an embryo in the ovisac.

h, The pedicle.

139

INDEX.

A.

Page
AcARi Crossii . . . .86
Aldous, Mr., microscopic artist . 112
Analogy not Identity . 24, 95

Animalcules, group of . 9, 28

cause of diseases . 90

fed with carmine . 46

with shells, or cases, 79

Azoic sedimentary strata . 87, 106

B.

Bacillaria

. 109

Baker on the Polype

. 20

. 76
20, 71, 76

, works of

Baker's Brachionus .

. 80

Beaded Melicerta

. 59

Bell-shaped Animalcules

42

Page
Bilin, Fossil Infusoria of . .102
'* Black Sea," Wandsworth

Common . . . .63
Brachionus . . , .79

Bakeri . . .80

urceolaris . .79

Branchiae . . 57, 67, 80

Brighton, marine animalcules of, 103

Bryozoa 65

Byron, Lord, quoted . . 3

C.

Carchesium . , . .49
Carmine, Vorticellee fed with . 45
Cells, the essential vital organs, 22, 98
— — , animals formed of . .25

, plants formed of . .23

, the seat of disease . « 25

140

INDEX.

Cellulosse

Chalmers, Dr., quoted

Chlamidomonas

CUia

of the Rotifers

Clapham Common,
from

Page
. 22
.^ 92
.' 37
30, 33, 47
. 35
Infusoria

Stephano-

ceros . . . .

Cloak-Monads

ConfeiTse . . . .

Consumption, benefits of Inhala-
tion in ... .

Coscinodisci . . . .

Crowned Wheel-animalcule

66
37
22

26

103

63

D.

Dancer, Mr., microscopes of .111
Darker, Mr., microscopic ob-
jects of . . . . 112
Development, theorj- of . . 95

of the egg in the

Rotifer . . . .75

of the egg in the

Stephanoceros . . .68

of the young of

the Stephanoceros . .67
Dick, Dr., quoted ... 5
Diseases caused by animalcules . 90
Drawings of microscopical sub-
jects . . . 112

E.

Page

Eggs of Infusoria . 59, 67, 75

Rotifer vulgaris . 75

Stephanoceros . . 68

Ehrenberg, M., works of . 29

Elegant Floscularia . . .61

Entozoa 104

" Explanation of the Vestiges "

quoted . . . .95
Eyes of Polygastria . . 51, 57

of Rotifera . . .57

F.

Fissuration, spontaneous
Floscularia

ornata .

proboscidea

Fossil Infusoria

of Bilin

f Brighton

of Ireland

of Virginia

of Yorkshire

Fresh-water Infusoria

Polype .

Fungi, sporules of .
Funsrus, Yeast

G.

Ganglia in Infusoria
Globe Volvox

37,47
. 58
. 61
. 6
81, 101
. 102
. 103
. 102
. 102
102
28
12
86
23

57
39

INDEX.

141

IPage

38

38

9

104

Gonium pectorale .

, self- division of .

Group of living animalcules
Guano, Infusoria in .

H.

Hall, Captain Basil, quoted . 8
History of Infusoria, Pritchard's, 110

Holland, Dr., quoted . 91, 105

Honey Floscularia . . 59, 61

Hornwort Limnias . . .58

Hydra 12

, arms of . . .16

capturing prey . .17

fusca . . . .14

' , gemmation of . .27

, mode of increase . . 26

■ , progression of . .13

, structure of . . .15

viridis . . . .13

, vivisection of . .18

vulgaris . . .14

' , young of . . .27

I.

Ichaboe, guano of . . .104
Ideal invisible world . . 1

Imperfect self-division of Infu-
soria . . . .49

JPage
Infusions, vegetable . .86

Infusoria . . . . 23, 30

, directions for collecting, 100

, fossil . .81, 101

, fresh-water localities of, 99

, general remarks on . 85

Infusorial earth . . .102

Jaws and teeth of Brachionus
Floscularia

garis

Notommata
Rotifera
Rotifer vul-

35, 56
Stephanoceros, 56

L,

Law of development . . 95

, creation by . . .105

Lee, Mr. Hamlin, observations

of . . . .63, 103
Leparia nivalis . , .23

Life in simple organisms . .11

, duration of, in Infusoria . 87

Limnias ceratophylli . . 58

Localities of Infusoria . . 99
Locke, quoted ... 5

Lyell, Mr., quoted . . .107
Lytton, Sir E. B., quoted 4, 92

142

INDEX.

M.

Mandl, M., on the microscope .
Masticatory organs of Infusoria,
Medical Notes, by Dr. Holland,

quoted . . . .
Medusae .....
Melicerta ringens
coloured by

carmine . . . .
Memoires sur les Polypes, par

Trembley
Microscopes . . . .

, Baker on the

, Mandl on .

, Pritchard on

Page

110

83

91
88
59

60

Milton, quoted
Monad of Volvox
Monads .
Monas crepusculum

grandis

termo .

. 21
. 109
. 71
. 110
. 28
. 2
. 39
29, 36
. 37
. 36
. 116

. vinosa . . . .116

vivipara . . .37

Muscular system of Infusoria 50, 53

N.

Nervous ganglia in Infusoria . 57
Notommata, jaws of . .54

Objects for the microscope . Ill

Ocellus, or eye-speck
Organic cells .

creation by law

Ova of Animalcules .
Owen, Professor, quoted

P.

Page

. 36
24, 98

. 105
59, 67
50, 78

Parasites on Rotifers

52

•Iv^ '^^r\4-r\rtf\n

105

Pedicle of VorticeUse

45

Physalia .

88

Physiological summary

49

Pitcher-animalcule .

79

Polygastria

32

,51

Polype, see Hydrce.

Portuguese man-of-war

88

Powell, Mr,, microscopes

of

.

110

Pritchard, Andrew, Mr.,

aiicro-

scopes of .

•

.

110

. works of

28,

110

R.

Reflections . . . .81
Respiratory tube . . .73*
Resuscitation of Rotifers . .77
Revolving Monads . . .39
Richmond, fossil Infusoria of . 103
Ross, Andrew, Mr., microscopes

of 109

Rotatory organs . . .52

INDEX.

143

Rotifera

-, eggs of .

-, jaws and teeth of

-, parasites on

Page
52,57
. 75
. 53
. 52
. 71

Rotifer vulgaris
■ , Baker's descrip-
tion of . . . .76

, cilia, highly

magnified view of . .35

, development of 75

, eggs of . .75

, resuscitation of 77

, rotators of . 74

, wheels of . 74

S.

Scallops, Infusorial shields from 103

Self-division of Infusoria .
Sliields of Infusoria
Smith, Mr., microscopes of
Stentor .

cseruleus

Mulleri

• polymorphus

Stephanoceros

37,

branchiae of
development

of

the eggs

the young

development of

ocellus of

47
79
110
43
44
43
43
63
67

67

67
66

Stephanoceros, sheath of

, teeth of .

, tentacula of

, Ehrenbergi

Strata, azoic
, infusorial

87

Page

65
56
64
66
106
81

38

111
23
49
19
21
41
57

T.

Tablet Monads

Topping, Mr., microscopic ob

jects of .
Torula cerevisise
Tree Vorticellse
Trembley, M., experiments of

, work of .

Trembling Animalcules
organs

V.

Vestiges of the Natural His-
tory of the Creation" 24, 94, 107
33
41
102
18
39
47
118

Vibratile Cilia
Vibrio ....
Virginia, Fossil Infusoria of
Vitality, divisibility of
Volvox globator
Vorticella convallaria
nebulifera

144

Vorticellse

-, arborescent

, fed with carmine

, stomachs of

Vorticellina

INDEX.

age

Page

44

W.

48

45

Water-Nymph Animalcule

. 58

46

Wealden strata

. 107

42

Wheel-animalcules .

35, 52

LONDON :

w. m'dowall, printer, pemberton row, GOUGH SaUARE.

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companion, not only of the geologist in his study, but also in the field ; while they
will also accompany the intelligent travellers of both sexes, as most instructive
and delightful Mentors in their journeyings among the grand and beautiful
scenes of our globe. The woi-k is, indeed, a classic of high excellence, of great
research, and formidable labom\" — American Journal of Science for January,
1845.

Thoughts on a Pebble; or, a First Lesson in Geology. The Seventh
Edition, with Eleven additional Illustrations. Just pii^blished. Price 3*.

" This elegant little book, primer-like in size, and illustrated by fine coloured
plates and wood engravings, serves still to convey some of the grandest truths in
Geology in the simplest guise. After what we know of its accomplished Author*
we might well expect, when he picks up and describes a pebble from the brook-
side, that we should find

books in the running brooks.

Sermons in stones, and good in everything.

It is almost superfluous to add, that the style is lucid, eloquent, poetical, and phi-
losophical, for all these attributes are combined in Dr. Mantell's works. The
elegant form of the little book, its snowy paper, excellent type, and rich illustra-
tions, I'ecommend it to the eye of taste; while to the philosopher, as well as to the
pupil, it presents truly a First Lesson in Geology, and cannot be perused without
pleasure and profit. It has passed through many Editions, and we wish they may
be repeated as long as the stars glow or the waters fiovi.^^— American Journal of
Science.

The Fossils of the South Downs; or, Illustrations of the Geology
of Sussex. 1 Vol. Royal 4to. ; with forty-two Engravings, Map, &c.
Price 3/. 3*.

WORKS BY DR. MANTELL.

The Fossils of Tilgate Forest; or, Illustrations of the Geology of
the South-east of England. 1 Vol. Royal 4to. ; with Twenty Plates of
the Fossils of Tilgate Forest. Price 11. \2s. M.

The Geology of the South-east of England. 1 Vol. 8vo. ; with
a Map, numerous Plates and Woodcuts. Price 1^. 1*.

PREPARING FOR PUBLICATION.

1. The Phenomena of the Nervous System; or, a Familiar Ex-
position of the nature and functions of the Nerves ; being the substance
of a course of popular Lectures, With numerous Illustrations.

2. A Geological Ramble round the Isle of Wight; illustrative of
the most interesting Geological Phenomena of the Island. With Map,
Sections, and numerous Illustrations.

ON

NATURAL HISTORY, SCIENCE, &c.,

PUBLISHED BY Mr. MURRAY.

GLEANINGS IN NATURAL HISTORY;

With Anecdotes of the Sagacity and Instmct of Animals, and Extracts
from the Unpublished Journals of Gilbert White, of Selborne. By
Edward Jesse, Esq. Sijcth Edition. Woodcuts. Fcap. 8vo. 66. 6</.

SCENES AND TALES OF COUNTRY LIFE;
With Recollections of Natural History. By Edward Jesse, Esq.
Second Edition. Woodcuts. Post 8vo. 12s.
" One of the most valuable additions that have been recently made to our prac-
tical knowledge in the Natural History of our own country."— Gentleman's
Magazine.

JOURNAL OF A NATURALIST.

Fourth Edition, with Woodcuts. Post 8vo. 9s. ^d.
*' A book that ought to find its way into every rural drawing-room in the king-
dom, and one that may safely be placed in every lady's hovL^oiv."— Quarterly
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MODERN BOTANY.

A Popular Introduction to the Natural System and Classification of

Plants, By Mrs. Loudon. Woodcuts. Fcap. 8vo. 8s.

" To any one who wishes to comprehend the names and nature of plants, this
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ELEMENTS OF GEOLOGY;
Or, the Ancient Changes of the Earth and its Inhabitants, con-
sidered as Illustrative of Geology. By Charles Lyell, Esq., F.G.S.
Second Edition. Woodcuts, &c. 2 vols. 12mo. 18«.

" Very interesting and amusing, and should be read by every one who takes an
interest in this rising branch of Natural History." — Jameson'' s Journal.
*' A Work that supersedes every other on geology." — New Monthly Magazine.

TRAVELS OF A GEOLOGIST IN NORTH AMERICA;

With ObseEvations on the United States, Canada, and Nova Scotia. By
Charles Lyell, Esq., F.G.S. Woodcuts. 2 vols. Post 8vo. U. l.y.

" We regard the work as one of the best books of travels that has appeared for
some year?,.''''— Spectator.

" Mr. Lyell visited America not merely as a man of science or a philosopher,
but as a man of sense and of the world, eminently imbued with qualifications to
constitute him an astute observer." — Literary Gazette.

RUSSIA IN EUROPE, AND THE URAL MOUNTAINS, GEO-
LOGICALLY ILLUSTRATED.

By Sir Roderick Murchison, G.C.S. With Coloured Map, Tables,
Woodcuts, Sections, &c. 2 vols, royal 4to.

"This work extends the Geological classification of strata, as determined by
modern investigations in the British Isles, France, and Germany, to European
Russia and the Ural Mountains — a region nearly twice as large as those districts
of Europe previously examined and described. It is thus an appeal to Nature on
a very grand scale, which, in confirming the sound inductions of the Geologist,
has elicited, it is hoped, new and important views."

TOUR THROUGH THE SLAVE STATES,
From the River Potomac, by Baltimore in Maryland, to Texas and the
Frontiers of Mexico. By G. W. Featherstonhaugh, Esq. With
Plates. 2 vols. 8vo. 1^. 6*.

*' His notices of the natural history, the mines, and other geological memo-
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THE GEOLOGY OF YORKSHIRE.
By John Phillips. Part I. — The Yorkshire Coast. Plates. 4to.
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4to. 2/. 12s. 6d.

PRACTICAL GEOLOGY AND ANCIENT ARCHITECTURE
OF IRELAND.

By George Wilkinson, Esq. Plates. Royal 8vo. II. 8s.

"The value of scientific knowledg-e, when applied to practical purposes, is strik-
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" The work is one which must be perused with profit by every architect and
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THE GEOLOGY OF CHELTENHAM AND ITS NEIGHBOUR-
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GARDENING FOR LADIES;

Being Practical Instmctions and Directions for the Pleasure and Kitchen
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HAND-BOOK OF NEEDLEWORK.

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PHILOSOPHY IN SPORT MADE SCIENCE IN EARNEST ;

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praise. " — Examiner.

JOURNAL OF RESEARCHES INTO THE NATURAL HIS-
TORY AND GEOLOGY OF COUNTRIES VISITED DURING
A VOYAGE ROUND THE WORLD.

By Charles Darwin, M.A., F.R.S. Second Edition, with Additions.
Post. 8vo. Is. M.

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YEAR BOOK OF NATURAL HISTORY;

Arranged for each Month. By Mrs. Loudon. With Forty Woodcuts.
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FACTS TO ASSIST THE MEMORY, IN VARIOUS SCIENCES.

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MEMOIR OF WILLIAM SMITH, LL.D., THE GEOLOGIST.

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"A fateful and gratifying recollection of the Father of Enghsh Geology."
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LIVES OF GALILEO, TYCHO BRAHE, AND KEPLER.

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"Gem-like portraitures of three extraordinary geniuses."— Z,«7er«rj/ Gazette.

LIFE OF JAMES WATT.

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which are pretty generally looked upon as abstruse and unattractive. These he
has illustrated by a train of acute and delicate thinking, ever imbued with the
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CHEMICAL MANIPULATION ;

Being Instructions to Students in Chemistry, on the Methods of per-
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KOSMOS ; or, a PHYSICAL SURVEY of the WORLD.

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HISTORY OF PAINTING— ITALY;

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DUTCH SCHOOLS.
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VOYAGE OF DISCOVERY AND RESEARCH, IN THE SOUTH-
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1839—43.
Comprising an Account of Kerguelen Island, Van Diemen's Land, Camp-
bell and Auckland Islands, New Zealand, the Falkland Islands, Cape Horn,
and New South Shetland ; the Discovery of an extensive Southern Con-
tinent, named Victoria Land, and the Determination of the South Mag-
netic Pole. By Captain Sir James Clark Ross, Knt., R.N. With
Plates and Maps. 2 vols. 8vo. Nearly ready.

FAVOURITE HAUNTS AND RURAL STUDIES ;

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Tlie following Works have already been Published.

BORROWS BIBLE IN SPAIN.

" There is no taking leave of a book like this."
— AthencBum.

BISHOP HEBER'S JOURNAL IN INDIA.

" One of the most delightful books in the lan-
guage."— Quarterly Review.

IRBY AND MANGLES' TRAVELS.
" By far the most welcome of the series." —
Literaiy Gazette.

DRINKWATER'S SIEGE OF GIBRALTAR.
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tion."— United Service Magazine.
HAY'S MOROCCO AND THE MOORS.
"Anew and highly interesting work."— G»eew-
ock Advertiser.

LETTERS FROM THE BALTIC.
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THE AMBER WITCH.

" Worthy of De Foe."— Quarterly Review.
SOUTHEY'S CROMWELL AND BUNYAN.
"Admirably written \i\e?.:'—Yorkshireman.

NEW SOUTH WALES.
"A pleasantly written account, by a lady." —
'Newcastle Courant.

LIFE OF SIR FRANCIS DRAKE.
«*This interesting and instructive volume has
enriched our biographical literature." — Edinburgh
Review.

FATHER RIPA'S MEMOIRS.
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not excepting ' Sorrow's Bible in Spain.' "Spec-

LEWIS'S WEST INDIES.

" These highly amusing stories of actual Ja-
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MALCOLM'S SKETCHES OF PERSIA.

" The Persians, as a nation, are here presented
with all the interest of our amusing friend Hajji
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ALGIERS AND ABD-EL-KADER.

•' A narrative more romantic, or of more ab-
sorbing interest, we have seldom met." — North-
ern Whig.

BRACEBRIDGE HALL.

" The most charming work ever written by
Washington Irving." — Cambridge Chronicle.

VOYAGE OF A NATURALIST.

♦' Mr. Darwin is a first-rate landscape painter,
and the dreariest solitudes are made to teem
with interest." — Quarterly Review.

THE FALL OF THE JESUITS.

" Written in a candid and moderate tone."—
Cheltenham Journal.

LORD MAHON'S LIFE OF CONDE.

" A very skilful and interesting narrative." —
Quarteiiy Rveieiv.

BORROWS GYPSIES OF SPAIN.

'« Evidently the work of a man of uncommon
and highly interesting endowments." — Quarterly
Revieiv,

MELVILLE'S RESIDENCE IN THE

MARQUESAS.
" Another • Robinson Crusoe.'" — Dublin Post.

JOHN MURRAY, Albemarle Street.

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;'^'