NEMATODA 



153 



The Trichina spiralis in its sexually-mature state is an ex- 

 tremely minute nematode helminth, the adult male measuring 

 only the T '^th of an inch, whilst the perfectly developed female 

 reaches a length of about i". The body is rounded and filiform, 

 usually slightly bent upon it- 

 self, and rather thicker behind 

 than in front, especially in the 

 males. The head is narrow, 

 finely pointed, unarmed, with a 

 simple, central, minute oral aper- 

 ture. The posterior extremity 

 of the male is furnished with 

 a bilobed caudal appendage, its 

 cloacal or anal aperture being 

 situated between these divergent 

 appendages. The penis consists 

 of a single spicule, cleft above, 

 so as to assume a V-shaped 

 outline. The female is stouter 

 than the male, bluntly rounded 

 posteriorly, having the genital 

 outlet placed far forward, at 

 about the end of the first fifth 

 of the long diameter of the 

 body. The eggs measure T ~" 

 from pole to pole. The mode 

 of reproduction is viviparous. 



As commonly observed in the 

 human body our young Trichinae 

 appear as spirally- coiLed worms 

 in the interior of small, globular, 

 oval, or lemon- shaped cysts, 

 which latter appear as minute 

 specks scarcely visible to the 

 naked eye. These specks resem- 

 ble little particles of lime, being 

 more or less calcareous accord- 

 ing to the degree of degenera- 

 tion which their walls have undergone. In shape and general 

 aspect they are not altogether unlike the eggs of certain nema- 

 toid worms, but their size alone sufficiently distinguishes them. 

 They measure on an average ^" in length by yjg" in breadth. 



FIG. 36. Larval Trichina coiled within its 

 capsule. After Bristowe and Rainey. 



