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structure; but doubts have latterly been thrown 
over his views by several accurate observers. M. 
Neyen says he never admitted the observations 
of M. Ehrenberg, because, in the first place, “I 
never could see the intestines which form the 
communication between the stomachs, and like- 
wise because I have observed, many years since, 
that the supposed stomachs were moving in the 
interior of the body of many species with great 
rapidity, in the same manner as the granules 
which circulate in the joints of the Chara. I 
have often seen Vorticellee with nine or ten large 
globules of indigo in the belly, which always 
moved round a centre, and thus showed in the 
most evident manner that they could not have a 
communicating canal between the stomachs pro- 
vided with an oral orifice and an extremity di- 
rected to the mouth.” M. Meyen considers that 
the inner surface of the first part of the canal 
is provided with cilia, which roll up alimentary 
and colouring matters into the form of a ball. 
When the ball has acquired the size of the stom- 
ach, it is expelled by its other extremity and 
pushed into the cavity of the animal. If solid 
substances do not exist in the surrounding liquid, 
then the balls are less solid; and appear in the 
forms which they present in the Infusoria exist- 
ing in colourless liquids. “ In this case the balls 
are composed of a small number of particles, and 
principally of a considerable mucous mass which 
unites them.” 
Of all the peculiarities by which animalcules 
are distinguished, those which respect their pro- 
pagation are the best deserving of attention. The 
concourse of the sexes is required to perpetuate 
the species among the larger animals; but, on 
descending the scale, some are found which in- 
dividually possess the characteristics of both sexes 
united in themselves, though their concourse is 
still required. In some, such as fishes, each pos- 
sesses the sexual organs of the male or female; 
but instead of their concourse, external fecunda- 
tion takes place; others again, such as the ani- 
mal-flower and polypus, are strictly hermaphro- 
dites ; and all produce their young without actual 
fecundation. The Infusoria propagate by eggs, 
by living foetuses, and by a portion of the body 
being detached from the body of the parent. 
Many species are undoubtedly hermaphrodite. 
Ehrenberg has calculated the fertility or capa- 
city of increase of microscopic animals to be so 
great that an imperceptible corpuscle can become, 
in four days, 170 billions, by gemmination or vol- 
untary division. 
There is a species of animalcule formed in in- 
fusions of hemp seed, which is described by M. 
Bonnet, as provided with a beak, or hook, at the 
anterior part. When an animalcule of this spe- 
cies. is about to divide, it seeks a convenient place 
at the bottom of its infusion,—commonly among 
that semi-transparent kind of mucilage which is 
formed in that of hemp seed. After searching 
and examining various places, it at last fixes on 
ANIMALCULE. 
one ; the body, which is naturally long, contracts; 
the curved beak is retracted or concealed, and 
the animal assumes a spherical figure. It next 
begins to revolve on itself, so that the centre of 
motion is fixed, or the sphere never changes 
its place. The motion is performed with the 
most perfect regularity, but the direction of ro- 
tation is constantly changing, in such a man- 
ner that the rotation may be first from right 
to left, then from before, and next from left to 
right; and all these changes are perfectly per- 
formed, without the animalcule or rotatory ma- 
chine changing its place. At length the motion 
accelerates, and at the point where the sphere 
seemed motionless, two cross divisions begin to 
be visible, exactly like the husk of a chestnut 
ready to burst. In a little longer, the animal 
appears agitated and making great exertions; at 
last it divides into four parts, each the same as 
the producing animalcule, but smaller. These 
grow larger, and each divides again into four, 
which in their turn increase and become equal 
to the parent,—if the word parent may be used 
in respect of this singular mode of generation. 
Propagation, by division of the body, is not 
confined to the more simple animalcules; it ex- 
tends to those of complicated structure, such as 
the Vorticelle, to which genus the one we have 
just described probably belongs. The Vorticellze 
are so denominated, from their power of creating 
a vortex in the fluid which they inhabit, by means 
of a circular row of fibrilli proceeding from the 
head or anterior period; and the floating parti- 
cles in the infusion, being absorbed, the animal can 
select its food from among them. The Vorticella 
hians, Plate II1., Fig. 4, propagates by a longi- 
tudinal division of the body. The figure of this 
animal resembles a ball, to which a filament or 
tail is attached. Previous to the commencement 
of division, the anterior part appears languid; 
then a small cleft is seen in it, which gradually 
increasing, each portion exhibits a mishapen ani- 
maleule. As the separation advances, the figure 
of each becomes more perfect, the division is at 
length completed, and both become entire and 
well-formed animals. The filament, however, be- 
longs only to one; the other acquires it. When 
the division is almost perfected, each part forms 
its own peculiar vortex, in points diametrically 
opposite. 
Several of the Vorticelle resemble a plant in 
miniature, consisting of a stem putting forth 
numerous branches and twigs, each terminated 
by a bell on its fibrille, which forms the active 
part of the animal. Every bell, with its filament 
and fibrilli, has a spontaneous motion indepen- 
dent of the rest; by alternate contraction and 
extension it can approach and recede from the 
stalk or branches, as in the Vorticella convalleria, 
Fig. 6. Sometimes the whole will instantane- 
ously close into a minute, round, white speck, at 
the root where it fixes, and again as instantane- 
ously expand into a perfect tree. The common 
