226 MOSQUITOES OF NORTH AMERICA 



De Vogel's paper has been criticised in that he produced no direct proof that 

 the Anopheles breeding in the sea-water pools are the ones responsible for the 

 malaria attributed to them. Furthermore, the species indicated, Anopheles 

 rossii, has been shown repeatedly to be incapable of transmitting malaria, the 

 parasites failing to develop within it. But recent investigations by Major Car- 

 ruthers in the Andaman Islands confinn de Vogel's conclusion that the Anoph- 

 eles breeding in the sea-water pools are responsible for malaria. The species, 

 however, is not Anopheles rossii, but J., ludlowii which greatly resembles it. The 

 question is clearly presented in a recent address by Surgeon-General C. P. Lukis, 

 Acting Sanitary Commissioner with the government of India, at Bombay, before 

 the General Malaria Committee. Speaking of the results of Major Carruthers, 

 he says : 



" The first thing that struck him was the remarkable fact that a large num- 

 ber of villages were quite free from malaria, in spite of the fact that many of 

 them were surrounded by riceland, swamp or jungle, whereas others showed a 

 considerable amount of malaria, the spleen rate varying from 25 per cent, to 

 50 per cent. Eventually it was noted that what determined the healthiness or 

 unhealthiness of a village was its proximity to the sea. Villages near the sea 

 were invariably malarious ; those remote from the sea healthy. Even a distance 

 of half a mile from the sea was sufficient to insure the endemic index being 

 per cent. This distribution of malaria was shown by actual measurement to be 

 exactly coincident with the occurrence of a particular species of anopheles, 

 namely Pseudomyzomyia Ludlowii, which appeared to breed chiefly in salt 

 swamps and brackish water, and which was undoubtedly the chief malaria carrier 

 in the Port Blair Settlement. 



" JSTow so closely does this mosquito, on casual examination, resemble M. Rossii 

 that, with reference to these two species. Professor Eysel has remarked upon 

 the folly of too nice distinctions in regard to the species of anopheles and the 

 transmission of malaria. Yet the existence of two distinct, though closely re- 

 lated species of anopheles is the explanation why, in the Andamans, the prox- 

 imity to ricelands and swamps is innocuous, provided that these are at a dis- 

 tance from the sea." 



According to these observations, the proposed destruction of Anopheles by the 



introduction of sea-water does not seem to be rational, at least with certain 

 species. At all events the specific identity of the Anopheles concerned must be 

 taken into account. It appears certain that while some species may breed either 

 in fresh or brackish water others occur exclusively in saline water. In certain 

 regions good tidal ponds prevent the breeding of Anopheles to some extent and 

 may in that affect the malarial rate. In others, where the species which breed 

 in salt or sea-water are present, and there are isolated stagnant pools, as has 

 been observed at Samarang and in the Andamans, such measures would have 

 little effect unless fish were admitted with the sea-water. 



According to C, S. Banks Anopheles ludlowii in the Philippines breeds in 

 both salt and fresh water. Banks gives an account of his observations in the 

 Philippine Journal of Science. In an earlier publication he had shown that 

 this species breeds in sea-water and claimed that it is a transmitter of malaria. 

 In his first paper he stated that this mosquito had never been found in the 

 Philippine Islands breeding in fresh water. Lfater, however, he took a trip to 



