DISCOVERIES 9 



collected in tubs and pots in the garden. On his 

 retirement from the Indian Service, the matter was 

 taken up by the Liverpool School of Tropical Medi- 

 cine, which had just been established, and expeditions 

 to West Africa were organised. This was the be- 

 ginning of a movement which has resulted in the 

 clearing of many unhealthy spots and districts in 

 warm climates. Reduction of domestic mosquitos 

 is a branch of this movement. 



The discovery of the transmission of malaria by 

 mosquitos was rapidly succeeded by that of the 

 transmission of yellow fever in a similar manner. At 

 the end of last century, Reed, Carrol, Lazear, and 

 Agramonte, working in Cuba, found that the ultra- 

 microscopic virus of yellow fever is conveyed from 

 one human being to another by the domestic species 

 of mosquito, Stegomyia calopus. This was followed 

 by the work of Graham of Beyrout, and of Ashburn 

 and Craig in the Philippines, which showed that the 

 similar virus of dengue fever is conveyed by the 

 domestic mosquito that is so common, Culex fatigans. 



In the meantime, measures against malaria and 

 yellow fever had been started in many places. For a 

 full description of these, " The Prevention of Malaria " 

 quoted above, and " Mosquito or Man," by Sir Rubert 

 Boyce (London, Murray), should be consulted ; there 

 is only space to mention shortly some of these cam- 

 paigns here. 



The first suggestion, that the best way to extirpate 

 mosquito-borne disease is to reduce the number of 

 breeding-places of the insects, was made in the letter 



