284 



ZOOLOGY 



SECT, 



specially interesting variation in the structure of the intestine 

 that occurring in Trichina, one of the Nematodes parasitic 

 in Man, in which this part of the enteric canal consists of a single 





FIG. 229. Dochmius duodenalis. 



cv. gl. cervical glands ; ph. pharynx, 

 bursa. (After Leuckart). 



A, male and female in coitu. B, anterior end, showing, 

 C, mouth with spines ; D, posterior end of male, with 



row of perforated cells : the lumen is therefore not inter- but 

 w?Y&-cellular, like the gullet of an Infusor. In the sexual stage 

 of Gordius the enteric canal undergoes more or less complete 

 degeneration. There are never any digestive glands, but in 

 Dochmius a pair of pear-shaped bodies of unknown function, the 

 cervical glands (Fig. 229, B, cv. gl.\ lie one on either side of the 

 pharynx and probably open externally near the mouth. 



In Nematoidea the coelome or body-cavity is always a single' 

 continuous chamber crossed in various directions by delicate fibres, 



FIG. 230. Transverse section of Gordius. l>m. ventral nerve-cord; c. cuticle et. ccelom 

 epithelium ; /<?/. epiderrn ; Ut. ccelome ; Im. muscular layer ; md. intestine ; mcs. mesentery; o 

 ovary ; u. uterus. (From Lang, after Vejdovsky.) 



but in Gordius sheets of coelomic epithelium or mesenteries (Fig. 

 230, mes.) extend longitudinally through it, dividing it into several 

 compartments. The most important of these are a median ventral 



