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CHAPTER VIII. 



On the Conditions Influencing the Prevalence of Mosquitoes, 

 and on the Prophylaxis of Malaria. 



In the previous issue of this handbook, but httle space 

 was devoted to this subject ; but though no more than a 

 year has elapsed, so much has been observed and v^^ritten 

 on the subject, that it is impossible to give any adequate 

 idea of the present state of our knowledge in a few 

 paragraphs, incidental to the life history of the Gulicidce, 

 so that it has become necessary to devote a special chapter 

 to the subject. To-day it may be fairly asserted that the 

 question of the connection between malaria and Mosquitoes 

 has passed beyond the tentative stage, and is indeed no 

 longer a " question," but an ascertained fact. 



Not only has the casual connection between the Mos- 

 quito-carried parasite and malaria been proved beyond 

 question of reasonable cavil, but experiments on a large 

 scale in the practical application of our present knowledge 

 to the prevention of malarial disease have shown that, 

 given sufficient intelligent co-operation of the affected 

 population, and sufficient earnestness on the part of the 

 governing authorities, it is quite possible to so avail our- 

 selves of this newly gained knowledge as to greatly diminish 

 if not to actually " stamp out " the disease. Without this 

 co-operation, however, we are helpless, for science can only 

 help those who will consent to help themselves. The 

 primary discovery of Laveran has gradually been so followed 

 up by Marchiafava, Golgi, Plehn, Celli, Grassi, and many 

 other distinguished observers in Europe, as to place 

 Laveran's "epoch making" discovery on the soundest basis ; 

 establishing the fact that we have to deal with not one only, 

 but at least three distinct species of blood parasite and 



