﻿IX, B, 5 Walker and Barber: Malaria in the Philippines 437 



Philippine Islands can be accurately determined. These aspects 

 of the problem are now being investigated by one of us (Bar- 

 ber), and already interesting and important results have been 

 obtained, which will be published later. However, the impor- 

 tance of the 5 species of Anophelinse, investigated in the trans- 

 mission of malaria in the Philippines, can be roughly estimated 

 as follows: 



Anopheles maciilatns is probably a moderately susceptible, 

 semiwild species, with a moderate avidity for human blood; but 

 on account of its very local distribution it probably plays a verj^ 

 small part in the transmission of malaria in the Philippines, 

 especially in the lowlands. It is said to be primarily a highland 

 species, and if it should be found to be more prevalent in the 

 mountain provinces it might prove to be of importance in the 

 dissemination of malaria in those regions. 



Anopheles sinensis, has a low, if not negative, susceptibility. 

 It appears from the literature, as well as from our own observa- 

 tions, to be extremely localized in its geographical distribution 

 in the Philippines ; it is scare, and is a relatively "wild" species. 

 Therefore, while the few experiments made with it showed 

 this species to have a relatively high avidity for human blood, 

 it is probable that its part in the transmission of malaria in the 

 Philippines is negligible. 



Anopheles barbirostris stands the lowest in our experiments 

 in its avidity for human blood, and it is a relatively "wild" 

 species. It appears to have a wide but scattered distribution in 

 the Philippines, and its susceptibility to infection with malarial 

 parasites is rather feeble. On the whole, it is probable that this 

 species plays a subordinate part in the spread of malaria in 

 these Islands. 



Anopheles rossii is one of the most domestic of the anophe- 

 lines, with a relatively high avidity for human blood. It is very 

 widely distributed, especially along the coast and lowlands, and 

 is relatively prevalent. Its susceptibility to infection with the 

 malarial parasite is rather low. It is possible that this species 

 may play a certain role in the dissemination of malaria, espe- 

 cially along the extensive coasts of this Archipelago. 



Anopheles febrifer is both a "wild" and also a domestic 

 species in so far as shaded breeding places are afforded, with 

 a relatively high avidity for human blood. It is by far the most 

 susceptible among the 5 species investigated, and is probably 

 the most susceptible species in the Philippines. If investiga- 

 tions, which are now being carried on by one of us (Barber), 



