104 



CCELELMINTHA. 



very simple. In Ascaris lumbricoides, 

 (Jig. 44, a,) when highly magnified, 

 is seen to be surrounded by three 

 minute rounded tubercles ; into each 

 of these, fasciculi, derived from the 

 longitudinal muscles of the body, 

 are inserted in such a manner as to 

 cause the separation of the tuber- 

 cles, and consequent opening of the 

 mouth, which is again closed by a 

 sphincter muscle provided for the 

 purpose. To the mouth succeeds a 

 short 03sophagus, (Jig. 44, 1 & 2, &,) 

 which is separated by a constriction 

 from the rest of the alimentary 

 canal, and would seem, from the 

 muscularity of its walls, to be an 

 agent employed in sucking in the 

 liquid food upon which the crea- 

 ture lives. The true digestive ca- 

 vity (Jig. 44, 1 & 2, c, c) is a sim- 

 ple and extremely delicate tube, 

 which arises from, the oesophagus, 

 and without presenting any appear- 

 ance indicative of separation into 

 stomach and intestine, gradually en- 

 larges as it proceeds backwards, 

 until it terminates at the hinder 

 extremity of the body by a narrow 

 aperture (Jig. 44, 1 & 2, d.) 



It would seem that the food of 

 these entozoa being already ani- 

 malized by having undergone a pre- 

 vious digestion, requires little further 

 preparation ; and we are little sur- 

 prised at finding in the generality of 

 the Coelelmintha no accessory glan- 

 dular apparatus appended to the di- 

 gestive canals for the purpose Lof 

 furnishing auxiliary secretions. In 

 two species only have tributary 



the aperture of the mouth, 

 Fig. 44. 



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