﻿EXPERIMENTS IN MALARIAL TRANSMISSION. 515 



LOCATION AND BUILDINGS. 



The navy-yard proper is located on a sand spit and is surrounded by 

 a wall built in Spanish times; all the offices and the quarters of most of 

 the naval and marine officers and the hospital are located within this 

 wall. Outside, and along the west beach of the island are the other 

 marine officers' quarters and eastward from these, at a distance of some 

 120 meters, are the five large buildings erected for barracks for the troops. 

 Four of these barracks are within a few meters of the swamp regions. 

 They are built on cement piers about 1 meter from the ground level and 

 are well ventilated. Sewage is carried into Subig Bay by pipe lines 

 and there is no stagnant water in the immediate vicinity. Each building 

 is provided with a tank on the upper veranda into which Avater is pumped 

 for bathing purposes and for flushing the closets. The ground area 

 beneath and around the barracks is kept in a scrupulously clean condition, 

 many of the posts and piers being frequently whitewashed and no weeds 

 are allowed to grow. The parade ground at the west and south of the 

 barracks is not yet finished and therefore it is cut in many places by 

 trenches and ditches into which tide water finds its way and where Culex 

 microannulatvs Theob., and Myzomyia ludlowii Theob., breed in great 

 numbers. Larva? of both the above-mentioned species of mosquitoes were 

 found at the Maquinaya rifle range, freely breeding in salt water less 

 than 60 meters from the camp, which consisted of tents for both officers 

 and men. 



According to regulations, all men are obliged to sleep under mosquito 

 nettings, but I am of the opinion that these do not completely serve their 

 purpose in preventing the men from being bitten, for few sleep so quietly 

 that at some time during the night their arms or legs do not come in 

 contact with the sides of the narrow nets, thus offering a ready mark 

 for mosquitoes. 



PLAN OF WORK AT OLONGAPO. 



It was decided that the first requisite was the discovery of all species 

 of mosquitoes which might play an important role in the transmission 

 of disease, as well as to study the conditions under which the insects 

 breed most readily. A considerable amount of time was consequently 

 spent in reconnaissance in the neighborhood both of Olongapo itself and 

 the rifle range at Maquinaya. During this period mosquito larvae were 

 collected and bred, and breeding grounds mapped out. This work enabled 

 me to narrow the species of Anophelince down to Myzomyia ludlowii 

 Theob., as the most probable transmitter of malaria. 



