ANIMAL PARASITES. 129 



accomplished by giving, after a day of fasting, two 

 doses of thymol (gr. 30 each) in brandy or whisky two 

 hours apart, and two hours later a dose of castor oil. 

 If ova are still present in the stools a few days later, the 

 same treatment should be repeated. 



Prophylaxis consists in not going bare-footed in 

 regions where the disease prevails, in boiling the drink- 

 ing-water, and in scrupulous cleansing of the hands 

 before meals. The stools of persons harboring the 

 parasites should be disinfected, and treatment instituted 

 in all cases where eggs are found whether symptom.s 

 of the disease are present or not. 



FLAT WORMS. 



Parasitic flat worms are divided into two orders, 

 the trematodes or flukes, and the cestodes or tape- 

 worms. The former are distinguished by possessing a 

 partial digestive canal but no anus; the latter by a 

 complete absence of alimentary tract. 



TREMATODES. 



Distomiasis is the name applied to diseases resulting 

 from trematodes or flukes. Flukes are mostly small, 

 flat, leaf-shaped worms, which, as above noted, are 

 without anal orifices. Usually they possess one or 

 more suckers and occasionally booklets. They are 

 mostly hermaphroditic. Only the more important 

 varieties will be referred to. 

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