58 ENTOZOA FOUND IN MAN. 



At about the age of two years entozoa become 

 common ; but the question of the frequency of worms, 

 in relation to the age of the individuals affected by 

 them can only be considered in a general manner. 

 Certain entozoa are more frequent at a particular 

 period of life, as is the case with the oxyuris and the 

 ascaris lumbricoides, which are most usually met 

 with in childhood, whilst other species are observable, 

 in nearly equal proportion, at all ages. 



Sex exercises a remarkable influence upon the 

 frequency of taenia, and this singular fact has been 

 remarked by many helminthologists, the cases of 

 taenia occurrmg in females being as three to two, 

 when compared with the cases occurring in males. 



The constitution, or the actual state of the 

 health, of an individual is commonly looked upon 

 as one of the predisposing causes of the existence 

 of worms ; and, from the fact that certain epizoa 

 (parasites affectmg the external parts of the body) 

 attack the mteguments of diseased and badly 

 nourished animals, it may be inferred that something 

 analogous occurs with regard to the entozoa. The 

 term helminthiasis is applied by some writers to this 

 constitutional predisposition, when it is strongly 

 marked. 



