164 PARASITOLOGY. 



normal with a few dark flocculi. As many as a 

 hundred flukes have been taken from the ducts of a 

 single liver. The liver is unfit for food. 



Symptoms. — Distomiasis or liver rot appears 

 mostly among cattle in the United States on account 

 of the fact that cattle are grazed on the low lying in- 

 fested lands ; while the sheep come mostly from the 

 high table lands where conditions are not favorable 

 for their development into the larval stage. In Eng- 

 land the sheep are most often affected on account of 

 the reversed conditions to what they are in the 

 United States. The symptoms given us by observers 

 in that country are as follows : The malady is di- 

 vided into four stages or periods. 



First period is that of immigration; the flukes 

 are small and do not cause excessive disturbance. 

 This period lasts from four to thirteen weeks. 



Second period is that of anemia after the thir- 

 teenth week from infestation ; the sheep are less 

 lively, the mucous membrane is pale, the appetite 

 good and the sheep show a tendency to fatten ( as a 

 result of the stimulus to the liver which causes an 

 increased flow of bile). In the latter part of this 

 period the appetite diminishes, thirst increases ; 

 rumination irregular; mucous membrane yellowish; 

 may show edema ; wool is dry and brittle, and the 

 sheep show great weakness. The feces contain the 

 ova of the fluke. 



Third Period. — This is a period of loss of flesh ; 

 the sheep becomes gradually weaker and emaciated ; 

 the temperature is irregular, the respiration feeble 

 and frequent ; pregnant ewes abort ; the milk of 

 nursing ewes is poor in quality. Oedema is noted 



