ECHINOCOCCUS. 443 



troublesome to children ; and also the Strongylus gigas, a 

 worm sometimes attaining a length of two or three feet, 

 and of considerable thickness, have been often found in 

 the kidneys of swine, and in the same organ of the human 

 body. This worm, by destroying the part in which it takes 

 up its abode, frequently causes the death of its host. 



The dreaded " Guinea -worm" (Filaria medinensis, fig. 



Fig. 216. A lunch of Echinococci frrkenfrom the human liver, magnified 

 250 diameters. 



215 A), appears only in tropical countries, Africa, &c. The 

 worm lives in the cellular tissue beneath the skin of man, 

 confining its attacks principally, though not exclusively, to 

 the lower extremities, where it produces considerable pain. 

 It is said occasionally to attain a length of twenty or 

 thirty feet : but its average length is five or six. It is 

 extracted by winding it very slowly round, an operation 

 in which great care is said to be necessary, as if the worm 

 be broken, its fluids produce a very painful effect. 



The Echinococcus is found in cysts. Fig. 21 G represents 

 a bunch taken from the liver of a boy who died in Charing- 



