﻿IX, B. 5 Walker and Barber: Malaria in the Philivpines 427 



From this table it is apparent that given a malarial patient 

 whose blood contains gametes above the limits of infectious- 

 ness, the percentage of infections and the intensity of infections 

 do not depend alone upon the number of gametes ingested, but 

 some other factors must be involved in their determination. 



James (1902) calls attention to the question of the maturity 

 of the gametes as bearing on the infectiveness of the blood for 

 the mosquito. He believes that the maturity of the gametes 

 should be determined at the time of every infection experiment, 

 by drawing some of the patient's blood on a microscopical slide 

 under conditions that induce exflagellation of the microgameto- 

 cytes in order to estimate the proportion of the mature gametes. 

 We have not attempted this, believing that if the blood contained 

 gametes in number well above the limits of infectiousness at 

 least a part of them would be mature. Variations in the matur- 

 ity of the gametes may be one of the factors that would account 

 for the irregularities in Table VII. 



THE AMOUNT OF QUININE ADMINISTERED TO THE MALARIAL PATIENTS USED IN 

 OUR EXPERIMENTS AND ITS EFFECT ON THE INFECTION OF THE MOSQUITOES 



Darling (1910) states that in his experiments the routine 

 ward treatment with quinine, grains 10 ter in die, in solution 

 apparently had no effect on the parasites and their develop- 

 ment in the gut of the mosquito. However, he cites one experi- 

 ment in which the patient had received no quinine for several 

 days before the mosquitoes were fed and none during the experi- 

 ment. In this experiment, one mosquito of the very suscep- 

 tible species. Anopheles albimanus, showed a very large number 

 (168) of zygotes in its mid-gut and 2 mosquitoes of the very 

 unsusceptible species. Anopheles pseudopunctipennis, became 

 infected. Therefore, he thinks that quinine may have a slight 

 inhibitory effect on the parasite in the mid-gut of the mosquito. 

 It would seem possible, although the gametes of the malarial 

 parasite are resistant to quinine, that if the patient was saturated 

 with the drug sufficient free quinine might be taken up with 

 the blood into the stomach of the mosquito to injure or kill 

 the delicate microgametes or the zygotes developed in the gut 

 of the mosquito. 



In Table VIII are given the total amounts of quinine received 

 by each of the patients during the period they were used in 

 our experiments, the average amount per day, the percentage 

 of infected mosquitoes obtained, and the average number of 

 oocysts in the mid-guts of the infected mosquitoes in each case. 

 The quinine was administered in the hospital, except in the 



