166 PARASITOLOGY. 



Animals hdested. — The ox, sheep, pig, etc. 



Parts Infested — Liver, sometimes the lungs. The 

 writer has noted one case of Hepatic Distomiasis in 

 a pig ; four specimens of the Distoma Americanus 

 were found. 



Cojiditions Produced. — The larval fluke upon being 

 taken into the stomach on grass is liberated by the 

 dissolving of the gelatinous capsule enclosing it. 

 It finds its way to the liver through the hepatic duct 

 and finally becomes stationary in a small bile duct ; 

 or it may penetrate the duct and become lodged in 



'^^ 



Fiff. 64— Distoma Americanus. 



a, Oral sucker. 



b, Ventral sucker. 



c, Intestine 



the tissue outside. It here forms a cyst which varies 

 in size up to a hen's ^ZZ» The outer surface of the 

 liver presents the appearance of black prominent 

 elevations. Upon section of these tumefactions they 

 are found to contain a cavity within, which is filled 

 with a chocolate-colored fluid and some debris, and 

 in the older cysts some earthy material. 



One or more flukes are found in. each cyst. The 

 portal lymph glands, that lie against the posterior 

 surface of the liver at a point where the portal vein 



