. Animal physiology. Physiology, Comparative; Physiology, Comparative. POLYGASTRIC ANIMALCULES. 115. given by Fig. 74; although the number of different forms there represented is very small. They are beings of extreme minuteness, distin- guishable only with the microscope; their bodies seem to be of jelly-like Softness, though FlG- Animalcules. ° i. Monads; ir. Trachelis anas. in. Enchelis, discharging they are Sometimes fscal matter; iv. Paramecium; v. Kolpoda; vi. Trachelis covered by a sheath asci° anb* of horny or even siliceous (flinty) matter; and their transpa- rency is suc
. Animal physiology. Physiology, Comparative; Physiology, Comparative. POLYGASTRIC ANIMALCULES. 115. given by Fig. 74; although the number of different forms there represented is very small. They are beings of extreme minuteness, distin- guishable only with the microscope; their bodies seem to be of jelly-like Softness, though FlG- Animalcules. ° i. Monads; ir. Trachelis anas. in. Enchelis, discharging they are Sometimes fscal matter; iv. Paramecium; v. Kolpoda; vi. Trachelis covered by a sheath asci° anb* of horny or even siliceous (flinty) matter; and their transpa- rency is such, that everything which goes on in their interior can be distinctly seen. Yet there is considerable difference of opinion amongst observers as to their internal structure. It is admitted on all hands that they have a mouth, or aperture, for the admission of food; and in general a second aperture for the rejection of that which has to be cast out: and that food is conveyed into the mouth by the action of the cilia which surround it. But there is considerable doubt, whether it then passes into a regular intestinal tube, from which a series of little bags or stomachs open off; or whether it floats loosely in the general cavity of the body. The former is the view adopted by the celebrated Prussian naturalist, Ehrenberg, who has devoted several years to the study of animalcules; and who has on this account named the class Polygastrica, or many-stomached Ani- malcules. The latter is the doctrine more generally entertained; and the question still remains to be decided. 137. These animalcules afford objects of never-ending inte- rest to the microscopic inquirer. The variety of their forms, the rapidity of their movements, (which are accomplished by the action of their cilia,) their vast numbers, their quickness of mul- tiplication, and the facility with which they may be studied, (for there is not a ditch, a stagnant pool, or a vessel of water in which organic matter has remained fo
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