﻿IX, B, 5 Walker and Barber: Malaria in the Philippines 397 



INFECTING THE MOSQUITOES 



The mosquitoes have, in most cases, been kept from twenty- 

 four to forty-eight hours without food after emerging before 

 use in our experiments. While at times they would bite well 

 on the same day that they emerged, on the whole they bit 

 better if kept without food until the second day. The time 

 of feeding the mosquitoes on the malarial patients was for the 

 most part in the early morning. The advantage of feeding the 

 mosquitoes in the early morning, rather than in the evening, 

 is that good light, necessary for separating the females that 

 sucked blood from the empty females and the males, is available. 

 Some attempts were made to induce them, by darkening the 

 cage, to bite during the daytime, but with little success. 



In the biting experiments, the lantern-chimney cage was 

 removed from the Petri plate and netting placed over the lower 

 end. The sides and bottom of the cage were wrapped with 

 black cloth, and the top, covered with netting, was applied to 

 the moistened skin of the patient. By holding the gauze-covered 

 end toward the light before applying it to the patient, most of 

 the mosquitoes could be induced to collect on the netting, which 

 was then applied to the skin of the patient. In most cases the 

 arm, but in some cases the body, of the patient was used for 

 biting. It was found convenient to place several cages in a 

 row in a valise or box not deeper than the height of the cages 

 to hold them in position, and then have the patient rest his 

 arm on the tops of the cages. Three or four cages and some- 

 times more were fed at one time on the patient. The cages 

 were left in position until the patient felt no more bites or until 

 it was considered that no more of the mosquitoes would bite. 

 This was usually from fifteen to thirty minutes. 



After the feeding, the gauze on the lower end of the cage was 

 removed and the cage replaced over the Petri dish. Our lots 

 of mosquitoes were allowed to bite the malarial patient on one, 

 two, or three, or even more successive nights or mornings as 

 circumstances or the purpose of our experiments demanded. 

 During this period they were given no other food. After the 

 feedings on infected blood were completed, the mosquitoes were 

 supplied with raisins and sufficient water and were kept in the 

 dark closet until ready for dissection. 



In the preliminary experiments to determine the capabilities 

 of the different species of mosquitoes to become infected with 

 the malarial parasites, no attempt was made to separate the 



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