﻿IX. B, 5 Walker and Barber: Malaria in the Philippines 425 



the same day that they emerged, but in general they bit better 

 on the second day after emergence. With reference to the sev- 

 eral species, while the differences are not pronounced, Anopheles 

 sinensis shows the largest percentage of individuals taking a 

 meal of blood, followed in order by Anopheles rossii, Anopheles 

 fehrifer, Anopheles maculatus, and Anopheles barbirostris. 



MALARIA PATIENTS USED TO INFECT THE MOSQUITOES 



Seventeen different malaria patients whose blood contained 

 gametes were used for infecting the mosquitoes in our experi- 

 ments. Of these, 8 were suffering with subtertian, 7 with ter- 

 tian, and 2 with quartan malaria. More experiments were made 

 with subtertian malaria, because this type was most frequently 

 met with and because the gametes persist in subtertian malaria, 

 while they quickly disappear from the blood in tertian mala- 

 ria, especially if the patient is on quinine treatment. Quartan 

 malaria was found only rarely, and consequently only a few in- 

 fection experiments were performed with this type of malaria. 

 Thirteen of the patients were Filipinos, of whom 11 were males 

 and 2 females; and 4 were Japanese, all males. The number 

 of cages of mosquitoes fed on one patient varied from 1 to 32, 

 and depended upon the persistence of the gametes in the blood 

 and the ability to keep the patient in our service. 



NUMBER OF FEEDINGS ON INFECTED BLOOD 



The mosquitoes were allowed to feed from 1 to 6 times on 

 the infected patient in the different experiments. In the earlier 

 experiments the number of feedings depended upon the supply 

 of mosquitoes and the availability of a gamete carrier ; in experi- 

 ments 95 to 227a, the mosquitoes were fed only once, when 

 those containing blood were separated from the empty females 

 and males. It is probable that a greater number of feedings 

 on infected blood would increase the proportion of infections; 

 but in these later experiments it was our purpose to obtain 

 comparable results, and this was possible only under uniform 

 conditions of experimentation. 



THE GAMETE COUNT IN MALARIA PATIENTS USED IN THE EXPERIMENTS 



In experiments 1 to 10, 17 to 19, and 29 to 33, the gametes 

 were not counted but were estimated as +, -! — |-, -| — 1-+; in 

 experiments 11 to 16, 20 to 28, and 34 to 55, inclusive, a differ- 

 ential count of gametes and leucocytes was made in thin blood 

 smears, from 200 to 600 leucocytes being counted; in experi- 

 ments 56 to 227a, the differential counts of gametes and leuco- 



