MALARIA AND THE MALARIAL PARASITE. 313 



occurred only when the blood had been removed from and was outside 

 the human body. I reasoned that if this exflagellation occurs only 

 outside the body, the purpose of the flagellated body must lie outside 

 the human body, and that therefore the flagellated body must be the 

 first phase of the malarial parasite outside the body, must be the first 

 step that the malarial parasite takes in passing from one human host 

 to another. There seemed to me to be a sort of logic in this. But 

 how was the malarial parasite to pass from one human being to another? 

 It was not provided while inside the human body with any organs of 

 locomotion or penetration; as far as we know the parasite is never 

 extruded in the excreta, neither does it habitually escape in hemor- 

 rhages. Therefore, the idea of a spontaneous escape of the parasite 

 from the human body had to be dismissed. I therefore concluded that 

 some extraneous agency must remove the parasite from the human 

 body, so as to afford the opportunity for this flagellation which I had 

 concluded must constitute the first step in its extra-corporeal life. In 

 casting about for an organism which could effect this removal I, for 

 many reasons similar in some respects to those that influenced the 

 savage African, the Italian peasant, King, Laveran and others, came 

 to the conclusion that the medium of removal and transit must be 

 the mosquito. I was so impressed with the probabilities of this double 

 hypothesis and with its extreme practical value, should it prove to be 

 correct, that I endeavored to leave England for a time and to visit 

 British Guiana or some such suitable malarial country where I might 

 work out the idea. Unfortunately, that could not be accomplished, 

 so I published my theory in the hope that it would appeal to someone 

 who might enjoy the opportunities denied to me. At that time 

 Surgeon-Major Eoss was at home from India and we had many con- 

 versations on the subject. I described to him my hypothesis, the 

 probabilities of which and the possibilities of which powerfully appealed 

 to his highly logical and practical mind. He undertook, when he re- 

 turned to India, to do his best either to establish or confute it. Accord- 

 ingly he set to work in India experimenting with mosquitoes and 

 malaria. 



Eoss was stationed in Secunderabad, in the south of India, where 

 there was abundant opportunity for experimental work — plenty of 

 patients and plenty of mosquitoes. He got patients with crescent 

 parasites in their blood and he got mosquitoes to bite them. He found 

 that in the course of a few minutes after the blood had entered the 

 insects' stomachs the crescent parasites proceeded to the formation of 

 sphere and flagellated body. But he got no further. This experiment 

 was repeated hundreds of times. Many of his preparations were sent 

 to me, and I could confirm from them the accuracy of his statements 

 on the subject. Ross was encouraged, for obviouslv we were on the 



