ORGANS OF DIGESTION. 



307 



tious residue of digestion. This simple form of digestive 

 apparatus found in the monads appears to belong to about 

 forty other genera of this class, which, from this circum- 

 stance of having no intestine passing through their body, 

 have been formed into a group designated anentera. In the 

 monas termo which is only about the two-thousandth of a 

 line in diameter, four to six of these small round stomachs 

 have been observed filled with colouring matter, although 

 they did not appear to be half the number which might be 

 contained in its bodyj each of these stomachs, of about the 

 six-thousandth of a line in diameter, appears to open, as in 

 other anentera, by a narrow neck into a wide funnel-shaped 

 mouth, surrounded by a single row of long vibratile cilia, 

 which attract the floating organic particles, or minuter 

 invisible animalcules, as food. This anenterous form of the 

 digestive apparatus, constituting almost the entire organiza- 

 tion, is found both in the sheathed or loricated and in the 

 naked forms, belonging to the lowest genera of this class, 

 many of which, however, have been found to be only the 

 young of supposed higher genera. 



The intestine which traverses the interior of the body in 

 all the higher forms of polygastrica, and communicates with 

 all the internal stomachs, presents very different forms in 



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