592 SUPPLEMENT 
which is a consequence of their littleness, and their not being 
developed for the most part, except in vegetable or animal 
infusions, which, however, is as yet but doubtful. Their ge- 
neral and particular form, the only thing which an observer 
can seize, confirms the differences in their organization. In 
fact, there are some whose form is truly binary and symme- 
trical, not only in their body, but also in the appendages at- 
tached to it, and which, besides, are clothed with a true cor- 
neous envelope. Some have the body elongated, vermiform, 
or depressed symmetrically, without any trace of appendages, 
as the vibrio, &c. Others, on the contrary, have a form evi- 
dently radiated, with a mouth or cavity apparent, as most of 
the vorticelle which we have seen are transferred by the 
Baron to the preceding class. Finally, there are some whose 
body is amorphous, or without any determinate form suscep- 
tible of definition, without buccal aperture, or trace of appen- 
dages, as the proteus, the volvox, and the monads. Those 
of the first sort are true animals, and even very elevated in the 
scale, since we find in them locomotive appendages, very 
distinct, which have been denominated wheels, filaments, &c. ; 
a tail composed of several articulations, and often terminated 
by appendages, variable in form and number; a true cepha- 
lothoracic buckler, covering a trunk more or less distinct; 
even a heart, eyes, and ovaries, have been remarked, and con- 
sequently we cannot doubt that these animals are provided 
with an intestinal canal. These animals thus exhibit some 
relations with those crustacea called entomostraca, by 
Miiller, and it is no very improbable conjecture, that some of 
these infusoria of this first section, may be only degrees of 
developments of species of entomostraca, well known in the 
adult state, for some of them are susceptible of very distinct 
metamorphoses, as has been proved by M. de Jurine, in the 
nauplia and amynome. As for the second form in the infu- 
soria, which is seen in the vibriones, we may conceive that it 
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