MxVNSON^S EXPERIMENT 35 



contains. Such translation was, in my opinion, a first 

 and necessary step for the parasite to take when it 

 would quit one human body and get into another. 

 Now, the agent which occurred to me as being the 

 most likely to effect the necessary step in the translation 

 of the filaria was the mosquito." 



JNlanson's suspicion that the mosquito was the 

 transmitting agent was soon strengthened by the dis- 

 covery that the filaria? increased in the blood during 

 the night — this fact he discovered himself after the 

 examination of the blood of 1,000 Chinamen whilst 

 in Amoy. He argued, was this great development of 

 the parasite in the blood dunng the night in any way 

 an adaptation to the nocturnal habits of the mosquito ? 

 Stimulated, as he says, by this further coincidence, he 

 . determined to make a practical test — just as, later, Ross 

 did in the case of malaria, and Reed, Carroll, Agra- 

 monte and Lazear in the case of yellow fever. For 

 this purpose Manson placed a Chinaman who had the 

 parasites in his blood under a mosquito net with hungry 

 mosquitos. The latter took their usual meal of blood, 

 and then INlanson set about dissecting them. 



" I shall not easily forget the first mosquito I 

 dissected so charged. I tore off its abdomen, and by 

 rolling a pen-liolder from the free end of the abdomen 

 to the severed end, I succeeded in expressing the blood 

 the stomach contained. Placing this under the micro- 

 scope, I was gratified to find tliat, so far from killing 

 the filaria, the digestive juices of the mosquito seemed 

 to have stimulated it to fresh activity." 



