CH. IX] OF DOMESTIC ANIMALS 309 



leaves of grass and other plants. The cysts are thus more 

 frequently swallowed by the close-cropping sheep than by 

 cows, which wrench off merely the upper portions of the 

 leaves at each bite. Watercress from infected districts, 

 especially if not thoroughly washed in salt water, is 

 a possible source of infection occurring to man. 



Symptoms. The symptoms and course of the disease 

 in sheep are as follows. The infected animal at first 

 appears to fatten. This appearance is not caused by any 

 real deposit of adipose tissue, but is due merely to serous 

 infiltration into the subcutaneous connective tissue. The 

 appetite then fails, great thirst is manifested and rumina- 

 tion becomes irregular. At the same time the skin and 

 mucous membranes of the mouth and nostrils become of 

 a whitish-yellow tint. Gradually the animal gets weaker, 

 and in from two to six months the disease proves fatal if 

 the parasites are present in any quantity. In severe 

 cases one sheep may have as many as a thousand flukes 

 in its liver. 



Precautions. The precautions to be observed are 

 (1) to avoid pasturing the flocks upon wet land or such 

 as is liable to be inundated by floods. In such situations 

 L. truncatula is likely to thrive in abundance. (2) To 

 apply top dressings of lime and of salt to the pasture: 

 by this means both the snails and any cercarise that may 

 be present are destroyed. Salt, even in comparatively 

 small quantities, is peculiarly fatal to the fluke in all 

 stages of its existence. (3) To supply dry food and 

 blocks of salt for the sheep to lick. (4) To destroy the 

 droppings of infected sheep, for it is in these that the 



