168 SOME MINUTE ANIMAL PARASITES 



and the domestic water-supply, supplemented by 

 water in the rejected household "odds and ends," 

 becomes of great importance in propagating disease. 

 Why should so much importance be attached to 

 Stegomyia fasciata, which is but one of many tropical 

 mosquitoes ? The answer is twofold : Wherever this 

 particular mosquito abounds, " yellow jack " may 

 possibly occur. Where the fly is absent, the disease is 

 absent. But though yellow fever had been known for 

 a long time, it was not till the end of the eighteenth 

 century that the association of the mosquito with the 

 disease was suspected. Then several investigators in 

 America drew attention to the fact that numbers of 

 mosquitoes were present during the epidemics that 

 visited various districts. Towards the end of the nine- 

 teenth century attention was drawn again to the fact 

 that the incidence of yellow fever coincided with the 

 appearance of the mosquitoes, and that when cold 

 weather came and killed the insects, the human 

 malady also disappeared. In 1878 an epidemic at 

 Mobile was controlled by anti-mosquito measures. 

 In 1881, Finlay ag-ain emphasized his idea that yellow 

 fever was mosquito borne. In 1882 the case was 

 clinched, for Dr. Gerard allowed a mosquito that had 

 fed on a fourth day yellow fever patient to bite his 

 hand, and in consequence he had an attack of yellow 

 fever. The final proof of the transmission of the 

 disease by the mosquito, S. fasciata, was made by 

 Reed, Carroll, Agramonte, and Lazear, and the seal 

 was set on the mosquito, for the information was 

 gained by the death of one of the heroic experimenters 

 (Dr. Lazear) from yellow fever, following the bite of 



