56 ENTOZOA FOUND IN MAN. 



tropical cotintries may give rise to actual epidemics 

 of the Guinea-worm ; amongst animals, the influence 

 which a humid character of the pastures exercises 

 upon the frequency of the distomum hepaticum in 

 sheep is well known, and it is stated that, in India, 

 the filariae observed in the eye of the horse become 

 much more common in the cold season, after the 

 abundant rains. 



A considerable relative degree of importance in 

 the production of worms has been assigned to the 

 manner of living. Sailors, for instance, are very 

 rarely affected with hydatids ; Dr. Budd thinks that 

 this exemption may be attributed to the circiunstance 

 that their diet, which consists chiefly of salt meat, is 

 probably unfavourable to the development of cystic 

 worms. 



It is a generally received opinion that it is the 

 mode of hviiig which renders the oxyu rides and 

 lumbrici more common amongst children than 

 amongst adults ; and this opinion seems to be con- 

 firmed by the fact that children residing in large 

 towns are less frequently attacked by these species 

 of entozoa than those who hve in the country. 

 Dr. Davaine states, however, that his own observa- 

 tions have led him to the conclusion that the greater 

 relative frequency of intestinal worms in the country 

 is due not to the use of fruits, of green leguminous 

 plants, and of farinaceous substances as articles of 

 diet, but to the quality of the water which is employed 

 for drinking and for culinary purposes. 



The common occurrence of the tsenia in adults 

 does not appear to depend so much upon a good or a 

 bad diet, as was formerly supposed, but rather upon 



