172 



TROPICAL MEDICINE AND HYGIENE 



Development is simple. The itching and irritation 

 caused by the worms round the anus, especially at night, 



FIG. 68. A, male, 

 and B, female, of Oxy- 

 uris vermicularis. 5/1. 



FIG. 69. On the left, female; 

 on the right, male; greatly en- 

 larged. A, anus ; M, mouth ; 

 V, vulva. (After Claus.) 



leads to scratching or rubbing of that region. The eggs 

 are then transferred to the fingers; from these they are 

 transferred to the mouth or nose, and so reintroduced 



