68 



the temperature was not high enough all the year round 

 to let the parasite develop in the mosquito. In hot 

 countries, however, this means could not stamp out ma- 

 laria. 



Last year also Major Ross went as the leader of an 

 expedition to Sierra Leone, sent by the Liverpool School 

 of Tropical Diseases to investigate the malaria question 

 in that part of the world. Here he found that the local 

 species of Anopheles carried malaria, and that these species 

 bred in a few local puddles. He confirmed his previous 

 observations that the genus Culexdid not carry the parasite. 

 Now Culex sp. breed in tubs of water, cisterns, wells, etc., 

 all artificial collections of water ; while he found that 

 Anopheles sp. rarely occur in these, but usually in small 

 natural ponds and puddles. The possibility of eradicating 

 malaria in a locality by the extermination of the dangerous 

 mosquito thus depends on the simple question, Do these 

 mosquitoes breed in sufficiently isolated and rare spots to 

 be dealt with by public measures of repression ? This was 

 one of the points which it was Major Ross's design to 

 obtain information on. His report was to the effect that 

 most of the malarial fever could be got rid of at almost 

 no cost, except a little energy on the part of the local 

 authorities. 



In the barracks at Wilberforce, a suburb of Free Town, 

 Sierra Leone, out of four hundred men there was a daily 

 average of forty ill with malaria. The place was infested with 

 mosquitoes ; but only the genus Anopheles was found, and 

 of these one third contained Zygotoblasts. The larvae of 

 these insects occurred chiefly in small stagnant pools in 

 which green algae were growing. One drachm of kerosene 

 oil was put on the surface of one of these pools, one square 

 yard in area, and all the Anopheles larvae were found dead 

 after six hours. 



Already, as you will have seen, a great advance has been 

 made by those engaged in the work, but much more remains 

 to be done. 



The lines to be followed are plainly indicated. Before 

 we can rest satisfied we should have a collection of mos- 

 quitoes from all parts of the world, and have accurate 

 and trustworthy determinations of the species, and know 

 what is possible about their distribution and life-history. 

 This certainly should be the work of the entomologist. 

 The Natural History Museum authorities are alive to the 

 importance of this work, and they have issued instructions 



