52 THOMAS L. BANCROFT. 



were afterwards made with filarise from mosquitoes that had been 

 dissected whilst alive to insure no injury to the filarise they 

 contained ; it made no difference however, for the young filarial 

 always died after three or four hours' immersion in water. In 

 mosquitoes that had died a natural death, when examined twenty- 

 four hours afterwards, the filarise were dead ; this occurred 

 whether the mosquito died on water or not. The filarise never 

 escape naturally from the mosquito's body. 



In order therefore, for the young filarise to reach the human 

 subject, it would appear that the mosquito must be swallowed. It 

 is not uncommon to meet people, who have accidentally swallowed 

 one of these insects, and it seems possible enough that such might 

 occur, especially in those who sleep with the mouth open. In the 

 act of killing mosquitoes with the hand their bodies are ruptured 

 and any young filarial, that might be present, would be extruded 

 on to the fingers and afterwards transferred to the mouth. 

 Mosquitoes when aged frequently get bogged in jam and honey,, 

 and by such food it is possible, although somewhat improbable, 

 they could gain entrance into the human stomach. To be infected,, 

 some may imagine that there must be an easier way than by 

 swallowing mosquitoes ; they must remember, however, that 

 Nature has not ordained that the life-cycle of entozoal parasites 

 shall be easily attained ; obviously for the reason that were it 

 easily accomplished, gross infection would occur causing the 

 death of the host and with him the parasites. 



Leuckart in his work 1 makes the following reference to Manson's 

 discovery, p. 64, footnote : — " From the observations of Manson 2 

 there can no longer be any doubt that the few embryos which can 

 pass without danger to themselves through the intestine of the 

 mosquito undergo further development in the body-cavity, in 

 consequence of which they now differ in size and in the structure 

 of the mouth parts from the embryo at an earlier stage. Manson 

 is of opinion that embryos, having thus reached a certain stage in 



1 Parasites of Man by Eudolph Leuckart — Young J. Pentland, 1886. 



2 Trans. Linn. Soc, Load., pp. 367-8, 1884. 



