of Rotatoria, they now form a distinct class
of the Invertebrata or backbone-less animals.
The high organisation which they and their
allies display has raised them to a place not
far inferior to that occupied by the vermiform
tribes. Of course, all aquatic larvæ,
whether of crustaceans, mollusks, or small
insects, must be excluded from the society of
true-bred Infusoria.

And true-bred they are, beyond denial. A
common mode of their increase is by
spontaneous division into two portions, each of
which becomes a perfect individual, to divide
shortly into two in its turn. Suppose that a
pig were an infusory animalcule. When full
grown, it would first grow still a little
longer; it would then become slenderer
about the middle of the back, as if laced in
by a relentless corset, till its waist became
as slim as that of a wasp or an hour-glass.
Meanwhile, there would sprout, on each of
the two portions of the pig, a head, or a tail,
or legs, or whatever else was necessary to
make both complete animals. Certain
Infusories subdivide by division across; others,
as the bell-animalcules, lengthwise. In this
case, it is as if the pig had the power of
ceasing to be a single gentleman by splitting
himself along the backbone. With some
Infusories, it seems to be a matter of
indifference whether they subdivide transversely
or longitudinally. But whatever the way,
increasing thus in geometrical progression,
the multitude of Infusories is at once
explained. In summer, animalcules are often
to be seen in the course of both these
subdivisional processes. But if we are looking
out for instances of pure and unmixed
descent, it is here, assuredly, that we shall
find it. Such Infusories may be considered
as aliquot parts of a like parent Infusory
which existed ages and ages ago, whose
subdivisions into two, without cessation, endow
it with a sort of material immortality.

Another curious mode of reproduction is
by what is called the encysting process,
which is common also to many of the algæ.
An Infusory stands still, ceases to move,
draws itself up into a purse or cyst; and
sometimes covers itself with a glutinous
exudation. In this state it remains for a
certain number of hours or days, during the
course of which the interior of the purse
may be observed to become filled with a
crowd of minute creatures, all in the highest
state of excitement and activity. The inside
of the cyst is like an eating-house which is
pestered with flies in the month of August.
Or it looks like a hive swarming with bees;
and, on beholding it, you almost fancy you
can hear them hum. This continues till
some portion of the parent-cyst gives way,
when out stream the merry prisoners, diverging
in all directions, to seek their fortune in
the world of waters.

It is natural to ask, "With what degree
of sensation or consciousness are these simply-
constituted Infusories gifted?" It is difficult
for us to enter into the personal feelings,
into the will and individuality, of creatures
so differently constituted to ourselves. Many
of their most remarkable features—such as
their " vacuoles," or the variable empty holes
that spontaneously form themselves in the
substance of their sarcode, particularly when
they have undergone a fast; and the
"contractile vesicles," which may be seen to
execute rhythmical movements of contraction
and dilatation at tolerably regular intervals
—serve some purpose in the economy of the
animals which can only be vaguely guessed
at by us. Perhaps the vesicles may aid in
diffusing through their bodies the liquid
product of the digestive operation—a
surmise which seems in some degree justified
by their unusual complexity in the genus
Paramecium. Able writers have been
unwilling to allow the Infusories any organs of
special sense, and have doubted whether
their very remarkable and diversified actions,
—their dartings forwards and backwards
like an arrow, their crawlings like a leech,
their leaps, spinnings, and undulations, are
really indicative of consciousness. If,
however, they are so endowed, as their
movements certainly seem to imply, they most
likely receive their perceptions of external
things from the impressions made upon their
general surface, and especially upon their
filamentous appendages. In a former number
it has been already stated* that Eating
is the act which distinguishes the animal
from the plant. Hunger, therefore, would
be the first and only sense felt by the lowest
creatures in creation. Taste, or the feeling
of repletion, would precede sight, hearing,
and smell; and consequently, of the seven
deadly sins, gluttony is the lowest and the
most abject. The Infusories may at least
have a sense of appetite before, and of
satisfaction after, their repasts. That they have
a preference for certain viands, is visible;
they do not feed by any means indiscriminately;
particular kinds of them are attracted
by particular kinds of aliment. For instance,
the crushed bodies and eggs of Entomostraca
are so voraciously devoured by the Coleps,
that its body is quite altered in shape by the
distension; and certain monads will crowd
around the body of a dying or still-
conditioned Euglene, and nibble at it, with the
same apparent voracity that a gang of rats
would overrun and devour the carcase of a
dead horse. Although their range of sensations
may be narrow, it is still something,
it is even much, if the Infusories enjoy a
faint sort of feeling of well being, after their
kind. Happiness is often compared to
sunshine. It is probable that the Great Being
who has poured out on the human race such
a transcendent flood of bliss and light, allows
also a dim glimmer of conscious comfort to

See Border-Land, page 273, of the present volume.