250 ENTOZOA. 



depends upon a correct appreciation of the relative structure, 

 chemical constitution, and disposition of the calcareous corpuscles 

 as observed in the various groups of Entozoa in which they are 

 known to abound, I have investigated the characters of these 

 singular bodies with very considerable care. In the Gysticercus ex 

 Potamochoero penicillato (as I originally termed it) I did not detect 

 any of these bodies within the walls of the caudal vesicle ; but 

 they were extraordinarily abundant within the head and neck, and, 





\0 





■■% 



£ ff L i Jf 



'Q 



dm m 



Fio. 55. — Enlarged view of the head of Ct/sticercus tenuicollis from the Bed Biver Hog {Potamo- 

 chcerus penicillatus) ; a, i, o, d, e, isolated calcareous corpuscles of various shape, andjf, g, h, i, 

 Ic, I, m, one of the corpuscles gradually dissolying under the action of liquor poiassa (X 220 

 diam.) — Original. 



by their highly refracting properties, imparted to the tissues (when 

 viewed by transmitted light) a dark pigment-like hue, almost 

 obliterating the hmiting membranes of the inverted head. They 



