252 



THE ANIMAL PARASITES OF MAN 



garian pigs, and i3'O9 per cent, of sheep were infected with Echinococcus ; 

 at the same time it was stated .that in regard to the native pigs the liver 

 was more frequently affected than the lungs (3-81 per cent, as compared 

 with 0-26 percent.); in sheep the lungs were more frequently infected (12-71 

 per cent, to 3-73 per cent.), whereas in the Hungarian pigs both organs 

 were almost equally infected (14-78 per cent, to 12-03 P er cent.). 



STRUCTURE AND DEVELOPMENT OF ECHINOCOCCUS 

 (CASEWORM). 



Echinococcus is represented by a spherical or roundish bladder 

 full of a watery liquid which originates from the oncosphere, and 

 in man may attain the size of a child's head, but remains smaller 



f* FIG. 177. Echinococcus veterinorum, natural size. The fibrous sac enclosing 

 the Echinococcus has been opened and laid back in five parts, so that the sur- 

 face of the bladder-worm may be seen with the brood capsules showing through 

 it. (After Leuckart.) 



in cattle (the size of an orange or apple). The thin wall of the 

 bladder is composed of an external stratified cuticle, and an internal 

 germinal or parenchymatous layer (endocyst). The latter again 

 exhibits two layers ; an outer layer of small cells that are 

 not very distinct, and an inner layer of larger cells. It con- 



r\ 



