PARASITES OP ANIMALS. 



85 



that are worth keeping, or are necessary, in order to expel 

 their parasitic worms, of which there are generally many 

 kinds. There are numerous drugs that are efficacious for this 

 purpose, some of which are mentioned under the beef tape- 

 worm (page 191). But the principal difficulty is this — those 

 who keep the most dogs, the worst dogs, and the dogs most 

 likely to harbor parasites in abundance, are the very persons 

 who are least likely to adopt such measures, either not know- 

 ing or not caring for the consequences. 



Tcenia coenurus Kuch., of the Dog ; and its young, the ^^ water- 

 brain'^ of Sheep. 

 In the substance of the brain of sheep there is often found 

 a soft tumor, often as large as a pigeon's egg, and sometimes 

 larger than a hen's egg, which is filled with a watery fluid. 

 Such tumors would go on increasing in size indefinitely, until 



Figure 62. 



death ensues. But even long before the result becomes fatal, 

 the health is seriously impaired. The brain is often found 

 much diseased, and in part quite disorganized — a state of 

 things which in man would produce incurable insanity. In 

 sheep, it causes " staggers," " gid," "vertigo," or " sturdy," 

 and other cerebral derangements. This disease is, in most 



Figure 62. — Ccenimts or water-brain of sheep. Natural size. Hearth and 

 Home, after Thudichum. 



