principle, which, the more it is inquired into, the more it will be
found to accord with the general operations in nature, namely, that
there is always a pre-existent principle of life necessary to the
organization both of animals and vegetables; that the alimentary and
other particles which are added to, or apparently belong to them,
produce nothing of themselves; they are incapable of forming the least
fibre, but they are able to become constituent parts of one organical
whole, together with the instruments whereby the forming principle is
manifested, and rendered capable of acting upon certain orders of
creatures.
VORTICELLA.
Animal calyce vasculoso; ore contractili ciliato, terminali. Stirps
fixa.
A small animal, with a vascular cup; the mouth is at one end ciliated,
and capable of being contracted, the stem fixed.
VORTICELLA ANASTATICA.
Plate XXI. Fig. 13, 14, 15, and 16*.
Vorticella anastatica, composita, floribus campanulatis, stirpe
multiflora rigescente.
Vorticella anastatica, compound, with bell-shaped flowers, and a rigid
stem.
Cluster polype, second species. Trembley, Philos. Trans. vol. xliv.
part. 2. p. 643.
These polypes form a group resembling a cluster, or more properly an
open flower; this flower or cluster is supported by a stem, which is
fixed by its lower extremity to some of the aquatic plants or extraneous
bodies that are found in the water; the upper extremity forms itself
into eight or nine lateral branches, perfectly similar to each other;
these have also subordinate branches, whose collective form much
resembles that of a leaf. Every one of these assemblages is composed of
one principal branch or nerve, which makes with the main stem of the
cluster an angle somewhat greater than a right one; from both sides of
this nerve the smaller lateral branches proceed; these are shorter the
nearer their origin is to the principal branch.
At the extremity of the principal branch, and also of all the lateral
ones, there is a polype or vorticella. There are others on both sides of
the lateral twigs, but at different distances from their extremity.
These polypes are all exceeding small, and of a bell-like figure; near
their mouth a quick motion may be discerned, though not with sufficient
distinctness to convey an adequate idea of its cause; upon the branches
of these clusters are round bodies, which will be more particularly
described presently.
Every cluster has eight or nine of these branches or leaves; they do not
all proceed from the same point, but the points from whence they set out
are not far asunder; each of these branches is bent a little inwards, so
that all of them taken together form a kind of shallow cup. If the eye
be placed right over the base of this cup, the appearance of the whole
eight or nine branches is like unto that of a star, with so many rays
proceeding from the center. If the cluster be slightly touched, all the
branches instantly fold up, and form a small round mass. The stem which
supports the cluster contracts also at the same time, folding up like a
workman’s measuring rule, that consists of three or four joints. This
extraordinary assemblage constitutes one organized whole, formed of a
multitude of similar and particular ones. A new species of society, in
which all the individuals are members of each other in the strictest
sense, and all participate of the same life.
A few days after one of these clusters is formed, small round bodies or
bulbs may be perceived to protrude in several places from the body of
the branch; these grow very fast, and arrive at their greatest growth in
two or three days. The bulbs detach themselves from the branches out of
which they spring, and go away, swimming till they can settle upon some
substance which they meet with in the water, and to which they fix
themselves by a short pedicle; the bulbs are then round, only a little
flatted on the under side, the pedicle continues to lengthen gradually
for about twenty-four hours, during the same time the bulbs also change
their figure, and become nearly oval. There are in a cluster but few of
these bulbs, compared with the number of the vorticellæ, neither do all
the bulbs come out at the same time. The bulb then divides lengthways
into two smaller ones, but which are still much larger than the
vorticellæ themselves. It is not long before these are separated like
the first, and thus form four bulbs on the same stalk; these again
divide themselves, and form eight; which again subdivide, and
consequently make sixteen. They are all connected with the stalk by a
proper pedicle, but they are not all of an equal size; the largest
continue to divide, and the smallest begin to open, and take the
bell-formed shape. Trembley observed from one round bulb, in about
twenty-four hours, by repeated divisions, one-hundred and ten vorticellæ
to be formed.
It has been asked with propriety, what plant or what animal could have
led us to expect an existence and mode of propagation similar to that of
the vorticella anastatica?
Fig. 13 represents one branch of the vorticella anastatica; on this
branch, besides the vorticellæ which are of a bell-like form, some of
those round bodies from which they first spring, and by which they are
so remarkably distinguished from any other species, may be seen.
Fig. 14 represents one of the globular bodies after it has parted from
the cluster, and has fixed itself to some other body, and after the
globule itself and its pedicle have begun to lengthen.
Fig. 15 represents the two bodies that were formed by the parting of
that which is shewn at Fig. 14.
Fig. 16* represents four that were formed by the separation of the two
bulbs, exhibited in the foregoing figure.
VORTICELLA PYRARIA.
Plate XXII. Fig. 25, 26.
Vorticella composita, floribus muticis obovatis; tentaculis bigeminis,
stirpe ramosa. Compound, with beardless oval florets, two double arms,
the stem branched.
It is somewhat of a pear shape, the base is pellucid, the top truncated,
the lateral arms, which are a pair on each side, cannot be distinguished
without some attention; they are sometimes to be seen disengaged from
the pedicle, and rolling swiftly in a kind of circle.
VORTICELLA CRATÆGARIA.
Plate XXII. Fig. 40.
Vorticella composita, floribus muticis globosis; tentaculis binis,
stirpe ramosa. Compound, with globous naked florets, two tentacules, and
a branched stem.
These vorticellæ are to be found in the month of April, both in the mud,
and upon the tail of the monoculus quadricornis; they are generally
heaped together in the manner in which they are represented in the
figure; they are of a spherical form, and united to one common stalk.
They are also often to be found without any pedicle. The body is rather
contracted; the aperture is circular, and surrounded with a marked
margin; it has two small arms. With a deep magnifier, a vehement
rotatory motion may be seen. They sometimes separate from the community,
and go forwards in a kind of spiral line, and then in a little time
come back again to the rest.
The figure represents a parcel of these vorticellæ united together.
Among the other authorities for this animal, Linnæus refers to Baker’s
description of the mulberry insect, “Employment for the Microscope,” p.
348, which, as it differs a little from the preceding account, we shall
insert here. That from which his drawing was made, and which he has
described, was found in a ditch near Norwich; he called it the mulberry
insect, from the resemblance it bore to that fruit; though the
protuberances that stand out round it are more globular than those of a
mulberry. It is to be seen rolling about from one place to another, and
is probably a congeries of animalcula; they are to be met with in
different numbers of knobs or protuberances, some having fifty or sixty,
others more or less, down to four or five. The manner of moving is the
same in all. They are generally of a pale yellow.
VORTICELLA OPERCULARIA.
Plate XXII. Fig. 29.
Vorticella composita floribus muticis ovalibus, stirpe ramosa. Compound,
with naked oval florets, and a branched stem.
These vorticellæ are of a lemon shape, and are generally found in
clusters, branching out from a stem, which mostly adheres to some
convenient substance.
That species of them which is described by Baker had a very short
pedicle, and the animals were much longer than those which are
represented at Fig. 29. There was no main stem, but all the pedicles
were joined in one center, round which the animals extended themselves
as so many radii, forming a very pleasing figure.
The mouths of these animalcula are not ciliated, but they are furnished
with a round operculum or cover, connected by a long ligament or muscle,
which extends downwards through the body, and is affixed withinside of
it, near the tail. This ligament may be contracted or dilated, so that
the cover can be removed to some distance from the mouth; in this
situation several short hairs maybe found to radiate from it; these have
a vibratory motion, by which they excite a current of water, most
probably to draw in the proper nourishment, after which they shut or
pull down the cover, which they again extend at pleasure: when the cover
is pulled close down, the mouth contracts, and no hairs are to be seen.
Fig. 29 represents the vorticella opercularia; ſ, the operculum removed
at some distance from the mouth, at t; it is nearly close at r, the
mouth contracted, the cover drawn in, and no hairs to be seen; u, a part
of the stalk, from which some of the animalcula are separated.
VORTICELLA UMBELLARIA.
Plate XXII. Fig. 30.
Vorticella composita, floribus ciliatis globosis muticis, stirpe
umbellata. Compound, with ciliated globous naked florets and an
umbellated stem.
Vorticella acinosa, simplex, globosa, granis nigricantibus, pedunculo
rigido. Müller Animal. Infus. p. 319.
We frequently find in divers places, upon water-plants, and other bodies
in the water, a whitish substance that looks like mould; plants, pieces
of wood, snail shells, &c. are often entirely covered over with this
substance. If we examine any of these minute bodies by the microscope,
we shall find such motions as will induce us to think them an assemblage
of living animals, severally fixed to the extremities of small stems or
pedicles, many of which are often so united as to form together a sort
of branches or clusters, from whence they have been termed clustering
polypes, or des polypes en bouquet.
These clusters are larger or smaller, according to the species of the
vorticellæ which form them, as well as owing to the concurrence of many
other circumstances. To obtain a clear idea of the figure of these
animals, it is best to observe the smaller clusters, as in the larger
they are often rendered less distinct on account of the number.
The length of those which are represented at Fig. 30, is about the 240th
of an inch; they are of a bell-shape. The anterior part a c generally
appears open, the posterior part is fixed to a stem or pedicle, b e; it
is by the extremity of this pedicle that the vorticella fastens itself
to any substance. It appears in the microscope of a brownish colour,
excepting at the smaller end b, where it is transparent, as well as the
whole pedicle b e. When the anterior part a c is open, a very lively
motion may be perceived about its edges; and when it presents itself in
a particular manner, something very much resembling the little wheels of
a mill, moving with great velocity, may be discovered on both sides of
the edges of this anterior part.
These vorticellæ are able to contract themselves suddenly. They may be
made to do this, either by touching them, or moving the substance to
which they are fixed. When they contract, the edges of the anterior
parts are drawn quite into the body; on resuming their former posture,
the edges may be seen to come forth, and put themselves in motion as
before. Minute substances that float in the water are often forced down
into these openings, and sometimes are thrown out again.
They are capable of swimming about singly, but their form is in that
case considerably different from that which they have when they are
fixed. To see regularly in what manner the clusters are formed, and in
what way these little creatures multiply, it is best to observe one that
is fixed by itself.
The pedicle of a single vorticella is at first short, but it soon grows
longer, and then begins to multiply, that is, to divide or split itself
into two lengthways. To effect this, the lips are first drawn into the
body, the anterior part closes and becomes round, and loses its bell
shape, the motion about the lips ceases, though a small degree of motion
may be perceived within the body. The anterior end flattens gradually,
and spreads wider in proportion as it grows smaller. It then gradually
splits down the middle, that is, from the middle of the head to the
pedicle, so that in a little time two separate round bodies appear to be
joined to the end of the pedicle that before supported but one.
The mouth or anterior part of each of these bodies now opens by degrees;
and in proportion as they open, the lips of the new vorticella begin to
display themselves. The motion before spoken of may then also be
perceived. Indeed it is the best time of observing it; it is at first
slow, but more rapid in proportion as the mouth opens, when it is as
swift as that of the vorticella before it began to divide, and we may
now look upon it as completely formed. A vorticella is generally about
one hour in dividing itself.
The lower of the three drawings, Fig. 30, represents two vorticellæ
joined by their posterior extremity to one pedicle; soon after the
division, each vorticella begins to shew a pedicle of its own.
Fig. 30 represents a cluster of eight vorticellæ; by this figure we may
form some idea in what manner the pedicles are disposed as their number
increases. There were at first only two at b, whose branches lengthened
to d, and then each of them was divided into two, now forming four;
these again lengthened and reached i; when they were again subdivided,
as in the figure.
The reader will join with Bonnet in admiring the group of wonders
afforded by a single spot of mouldiness. What unforeseen, varied, and
interesting scenes are presented within so small a compass! what a
theatre is exhibited to a thinking mind! But our abode is so recluse,
that we have but a glimmering view of it: how great would our
astonishment be, if the whole spectacle was disclosed to us at once, and
we were enabled to penetrate into the interior structure of this
wonderful assemblage of living atoms! Our eyes see only the gross parts
of the decorations, whilst the machines that execute them remain in
impenetrable darkness! Who shall enlighten this profound obscurity, or
dive into an abyss where reason is lost; or draw from thence the
treasures of wisdom concealed within it? Let us learn to be content with
the small portion that is communicated to us, and contemplate with
gratitude the first traces of human understanding that are imparted to
us in these discoveries.
VORTICELLA BERBERINA.
Vorticella composita, floribus ovalibus muticis, stirpe ramosa.
Compound, with oval beardless florets.
This is a species of the vorticellæ, which resembles the preceding one
in many respects, particularly in being multiplied in the same manner,
that is, by dividing or splitting, according to its length.
They are more slender than the vorticella umbellaria; the branches of
the clusters are transparent. When many of them are together, they
appear of a changeable violet colour; the clusters are not unlike a
sprig of spun glass. The motion of the lips is not so easily
distinguished as in the foregoing species, though it may be observed in
these whilst they are opening and completing their formation. For at
these times the motion is but slow, whereas it becomes afterwards very
quick in those that are arrived at a state of perfection.
All the cluster vorticellæ detach themselves from time to time from the
stem, and from these they swim about till they fix again upon some
convenient substance; the branches, when deserted, bear no more
vorticellæ.
VORTICELLA DIGITALIS.
Plate XXII. Fig. 31.
Vorticella composita, floribus cylindricis, unisulcatis semiclausis,
stirpe ramosa. Compound, with cylindrical florets.
Vorticella composita, cylindrica, crystallina, apice truncata et fissa,
pedunculo fistuloso ramosa. Müller Animal. Infus. p. 327.
This species of the vorticella is very scarce, it seems only to have
been seen by Rösel, who found it on the monoculus quadricornis, till it
was discovered in the year 1784 by Müller, who had sought for it several
years before, but in vain.
The body is cylindrical, crystalline, and appears almost empty; it has
three pellucid points disposed lengthways, the apex is truncated in an
oblique direction, the margin bent back. The upper part contracts
itself, and the margin then assumes a conical shape, with a convex
surface; there are in general but few branches from the principal stem,
and these are short and thick. It excites an undulatory motion, but no
hairs, nor any rotatory motion, have been discovered. Fig. 31, o and n,
represents the vorticella adhering to the monoculus quadricornis.
VORTICELLA CONVALLARIA.
Plate XXII. Fig. 39.
Vorticella simplex, gregaria, flore campanulata mutico; tentaculis
bigeminis, stirpe fixa. Simple, but gregarious, the florets bell-shaped,
with two pair of little arms, and a fixed stem.
Vorticella simplex, campanulata, pedunculo rotortili. Müller Animal.
Infus.
These vorticellæ, or bell-animals, as they are termed by Baker, are
generally found adhering to some substance in the water; they are
represented here as found by Rösel, fixed to a curious cornu ammonis,
with points projecting from the back. To the naked eye they appear only
as so many little white points, but under the microscope, as little
bells, agitating the water to a considerable distance. The stems of
these have a particular motion, they draw themselves up and shorten all
at once, taking the form of a spiral wire or screw; in a moment after
they again resume their former shape, stretching themselves out straight
as before. Many of them may be seen at times adhering to each other by
their tails; the cilia, which are two on each side of the mouths, are
very seldom to be perceived.
VORTICELLA URCEOLARIS.
Plate XXII. Fig. 33, 34, 35, 36, 37, 38.
Vorticella simplex, pedunculata, ore dentato. Single, with a short tail,
and toothed mouth.
Brachionus capsularis testa ovata apice sexdentata basi incisa, cauda
longa bicuspi. Müller Animal. Infus. p. 356.
To the naked eye it appears as a white moveable point; but when examined
by the microscope, a tail projecting from the lower part is discovered,
and a double rotatory instrument is seen, which it can conceal or expose
at pleasure. It has been seen and described by most microscopical
writers; but as Baker’s seems to be the most perfect description, I
shall principally follow his account of it.
He discovered three species of them, two of which are included under the
vorticella urceolaris. Fig. 33, 34, 35, are of the first species; Fig.
36, 37, 38, are of the second kind. The first sort, when extended, is
about twice as long as it is broad. It is contained in a shell; the fore
part of this is armed with four sharp teeth or points; the opposite side
has no teeth, but is waved or bent in two places, like the form of a
Turkish bow. At the bottom there is a hole, through which it pushes the
tail. It fastens itself by this tail to any convenient substance when it
intends to use its rotatory organs; but when it is floating in the
water, and at all other times when not adhering to any body, it wags the
tail backwards and forwards something like a dog.
We may consider it as divided into a head, thorax, and abdomen; each of
which may be extended and contracted considerably: it can, by dilating
all three, protrude the head beyond the shell, or by contracting them,
draw the whole body within the same.
The head, when extended, divides itself into two branches, between
which, another part, a kind of proboscis, is pushed out; at the end of
this are two fibrils, that appear when they are at rest like a broad
point, but which can be moved to and from each other very briskly with a
vibratory motion, see Fig. 33.
The form and situation of the two branches are sometimes changed, the
ends thereof becoming more round, and the vibratory motion is altered to
a rotatory one: this alteration is represented at Fig. 34: the head also
appears in this figure. The thorax is annexed to the lower part of the
head; it is muscular: within it there is a moving intestine, which has
been supposed to be either the lungs or the heart of the little
creature, see b, Fig. 33 and 34.
A communication is formed between the thorax and the abdomen by means of
a short vessel c, whose alternate contractions and dilatations occasion
the abdomen to rise and fall alternately, having at the same time a sort
of peristaltic motion. The food is conveyed through this vessel into the
abdomen, where it is digested; it is then discharged by the anus, which
is placed near the tail.
The tail has three joints, and is cleft or divided at the extremity, by
which means it can better fasten itself to suitable objects. It is in
general projected from the lower end of the shell, moving nimbly to and
fro, serving the animal as a rudder when it is swimming, to direct its
course.
When the water in which the little animal is placed is nearly dried
away, or when it has a mind to compose itself to rest, it contracts the
head and fore-part of the body, brings them down into the shell, and
pulls the tail upwards, so that the whole of this minute creature is
contained within the shell, see Fig. 35. The shell is so transparent
that the terminations cannot be easily distinguished when the animal is
extended; but whatever is transacted within the shell, is as plain as if
there was no substance between the eye and the interior parts.
Fig. 36, 37, 38, exhibit the appearance of another species of these
animals, which differs from the foregoing kind. This has also a head, a
thorax, and abdomen, but then they are not separated by a gut or
intermediate vessel, as in the former, but are joined immediately
together, and at the place where in the first kind a moveable intestine
was seen; in this a muscle, most probably the heart, may be discovered;
it has a regular systole and diastole: this part is intended to be shewn
at a, Fig. 36, 37, 38. Like the other, it draws the head and tail within
the shell, which then appears to have six teeth or spikes on one side,
and two on the other. It very seldom protrudes its head so far out as
the other; sometimes the fibrillæ may be seen within the margin of the
shell.
Both species carry their young in an oval integument or bag, fastened
externally to the lower part of the shell, somewhere about the tail;
these bags are sometimes opake at one end, and seemingly empty at the
other, see d, Fig. 34: sometimes the middle is opake, with a transparent
margin, see b, Fig. 36.
It is highly entertaining to see a young one burst its integument, and
gradually force its way out; in performing this operation, it is much
assisted by the motion of the tail of the parent. The head part comes
out first, it then sets its rotatory organ in motion, by which it is
completely disengaged, leaving the integument behind, which the
vorticella freed itself from by repeated strokes with its tail. A young
one almost disengaged is seen at b, Fig. 38; another embryo, c, was left
adhering to the shell.
There are four more species of the vorticellæ mentioned by Linnæus,
which are, the vorticella encrinus, the vorticella polypina, the
vorticella stellata, and the vorticella ovifera; which, being marine
animals, do not come properly within our plan. The vorticella polypina
will be described hereafter.
TUBULARIA CAMPANULATA.
Plate XXII. Fig. 32.
Tubularia reptans, tubis campanulatis. Creeping, with campanulated
tubes.
It is called by Baker the bell-flowered, or plumed animal.