18 ENTOZOA FOUND IN MAN. 



invaginated in the caudal vesicle, which is then 

 generally destitute of any external appendage, and 

 presents at one pomt of its surface a sHghtly percepti- 

 ble foramen. 



As the cysticercus gets older it undergoes con- 

 siderable changes ; a black pigmentary deposit mvades 

 the suckers, and especially the rostellum, which 

 becomes of a firm consistence ; the hooks fall off, or 

 are destroyed ; the foramen of the vesicle is con- 

 tracted or entirely closed, and no longer permits of 

 the extrusion of the head ; besides these changes, 

 the vesicle becomes altered in form, and acquires an 

 abnormal size, or is divided into segments, but it 

 does not produce any new heads. 



Cysticerci exist in serous cavities, and in paren- 

 chymatous organs ; in the latter case they are always 

 enclosed in a cyst. These worms are peculiar to the 

 mammiferas. 



Cysticercus Cellulosce^ (Rudolphi). — This is an 

 elhptic vesicle, upon which no external appendage is 

 usually seen, provided with a very small and scarcely 

 visible foramen : the head is almost quadrangular ; 

 this parasite possesses a double circlet of hooks, 

 amounting to 32 in the cysticercus observed in man ; 

 the neck is very short, and larger in front than 

 behind ; the body is cylindrical, and longer than the 

 vesicle ; the large diameter of the vesicle is about 

 one-third of an inch. The longitudinal furrows upon 

 the head are strongly marked ; calcareous corpuscles 



* The word telce, with which the adjective cellulosiB agrees, is 

 understood. Its name is derived from its being found in the 

 cellular, now called areolar, tissue. 



