40 GENEEAL HISTOKT OF 



and diaphanous, save in the cases where the surface appears reticu- 

 lated fi'om contraction. 



" The fleshy substance of the Infusoria, isolated by tearing, or by 

 the death of the animalcule, appears in the li(;[md as lenticular discs 

 or globules, which refract light but slightly, and are capable of form- 

 ing spontaneously, in their substance, spherical cavities, analagous, 

 in appearance, to the vesicles of the interior. 



The vesicles formed in the interior of the Infusoria are destitute 

 of a proper membrane, and can contract even to so gi'eat an extent as 

 to disappear, or, several may coalesce or unite together. Some are 

 produced at the base of a sort of mouth, and are destined to contain 

 the water swallowed with the aliments ; they then pursue a certain 

 course, in the interior, and conti^act, and leave nothing in the middle 

 of the fleshy substance except those particles not digested, or they 

 can evacuate their contents externally, by a fortuitous opening, 

 which may be reproduced several times, although not as the identical, 

 yet towards the same point, and which may load to the belief of the 

 presence of an anus. 



" The vesicles containing the aliments are independent, and 

 neither communicate with an intestine nor Avith each other, save in 

 those cases where two vesicles incorporate together. 



" The other vesicles, which contain nothing but water, are formed 

 much nearer the sm-face, and appear to be able to receive and expel 

 their contents through the meshes of the tegument. "We may, with 

 Spallanzani, consider them as respiratoiy organs, or, at least, as 

 intended to multiply the points of contact of the interior substance 

 and the surrounding fluids. 



" The external organs of motion are flagelliform filaments, or 

 vibratile ciHa, or cirrhi, of more or less size, or fleshy prolongations; 

 which, according, as they are more or less consistent, appear formed 

 of the same living substance, and are conti'actile themselves, through- 

 out the whole of their extent. None are dermoid or comeaceous, 

 or secreted by a bulb. Except some contractile integuments, the 

 pedicle of Vcrticellae, and the bundles of homy spicula, which invest 

 the mouth of certain species; all the li-ving portions of the Infusoria 

 decompose almost immediately in water, after the death of the animal. 



*' The eggs of the Infusoria, thcii- generative organs, their organs 



