ECHINOCOCCOSIS OF THE LIVER. 



285 



Young animals are most exposed to this disease ; in adults or aged 

 animals the migration and development of the embryo are more difficult. 



Fig. 126. — Diagram of an echinococcus hydatid, cu, Thick external cuticle ; 

 jja, parenchym (germinal) layer ; c, d, e, development of the heads, 

 according to Leuckart ; /, g, h, i, h, development of the heads accord- 

 ing to Moniez ; I, fully-developed brood capsule with heads ; m, the 

 brood capsule has ruptured, and the heads hang into the lumen of 

 hydatid ; n, liberated head floating in the hydatid ; o, _^, q, r, s, mode of 

 formation of secondary exogenous daughter cyst ; t, daughter cyst with 

 one endogenous and one exogenous grand- daughter cyst ; u, v, x, forma- 

 tion of endogenous cyst, after Kuhn and Davaine ; y, z, formation of 

 endogenous daughter cysts, after Naunyn and Leuckart ; y, at the 

 expense of a head, z, from a brood capsule ; evag^ constricted portion 

 of the mother cyst. (After R. Blanchard, 1886.) 



These embryos perforate the tissue of the liver, become fixed in it, 

 and derive from it the nourishment necessary for their conversion into 

 cystic bladders of varying size, either sterile or fertile. 



The number of vesicles is rarely large, and when only one or two are 



