﻿IX. B, 6 Walker and Barber: Malaria in the Philippines 395 



In these cages the mortality of the mosquitoes was low, even 

 during the hot season. 



The cages were kept in a dark closet in the laboratory at 

 room temperature. In order to keep out the ants, the legs of 

 the closet were set in tins of petroleum. When not fed on blood, 

 split raisins, placed on the netting covering the top of the cages, 

 served as food for the mosquitoes. Every morning the cages 

 were gone over and fresh water and food supplied. The cages 

 were changed occasionally when they had become soiled. It 

 was found that the mosquitoes bit better if no food was supplied 

 before and between the feedings on blood. 



IDENTIFICATION OF THE SPECIES OF THE MOSQUITOES 



The species of each mosquito was determined when it was 

 removed from the cage for dissection. All of the males and 

 such females as died in every cage and the remains of every 

 female dissected were preserved for confirmatory identification. 

 These confirmatory identifications were made by Mr. Charles S. 

 Banks. 



THE SELECTION OF PATIENTS FOR INFECTING THE MOSQUITOES 



A routine blood examination was made of every patient en- 

 tering the hospital at the estate. In addition, large numbers 

 of blood slides were made of the laborers in the bunk houses 

 on the plantation and of the inhabitants of the outlying barrios. 

 Whenever a blood slide showed malarial parasites, it was 

 examined especially for the presence of gametes, and if they 

 were found in numbers that appeared to justify it a differential 

 count of the gametes and leucocytes was made to determine if 

 the gametes were sufficiently numerous for use in infecting the 

 miosquitoes. When a patient was found to be suitable for our 

 experiments, attempts were made at once to induce him to 

 submit to the bites of our experimental mosquitoes. This was 

 usually accomplished by a little persuasion and a small monetary 

 compensation. The hospital patients were available at any 

 hour for our experiments; gamete carriers from the plantation 

 or outlying barrios reported to us outside of their hours of 

 labor, either in the evening or early in the morning. Gamete 

 carriers from outside barrios were several times taken wholly 

 into our employ, and paid the same wages they would have 

 received if employed at their regular work. Such carriers were 

 not given treatment, unless they developed marked symptoms, 

 until we were through with them. 



