214 STITT. 



The soil conditions mentioned above probably to a great extent ac- 

 count for the low incidence of hookworm disease as brought out in our 

 examinations. Instead of a fine-grained, sandy soil which holds mois- 

 ture tenaciously "^ we have here a coarse-grainjed sand which dries up 

 completely almost as soon as the rain stops falling. Stiles attaches 

 importance to the consideration that a wooded location is favorable to 

 the development of hookworms because the shade of the trees counteracts 

 the injurious effects of drying on the larvae. There are practically no 

 shade trees in this section. The frequent flooding of low-lying sections 

 with sea water at the time of high tides must also influence the possi- 

 bility of infection. 



Our findings as regards Strongyloides (0.1 per cent) were far below 

 those reported l)y Garrison at Bilibid (3 per cent) and at Taytay (0.7 

 per cent) . Eissler and Gomez found 8.24 per cent infected in Las 

 Piiias, but no cases were encountered in Tuguegarao and Santa Isabel. 

 The same factors influencing hookworm infection in this locality may 

 be operative for Strongyloides. Garrison found 0.2 per cent of the 

 individuals examined at Taytay to be infected with ciliates, while Gomez 

 and Eissler failed to find such infections at Tuguegarao or Santa Isabel. 

 We found a single case in the 932 examinations. 



Our three cases of tapeworm infection were with Twnia saginata. 



' Views of Nicholson and Rankin as to favorable soil for hookworm develop- 

 ment. 



