38 Proceedings of the First Convention 



during the malarial season, — enjoying complete immunity from 

 attack though nearly every one unprotected in the villages 

 about them was ill. 



(B) Practical Proofs are briefly (i) that the Anopheles 

 mosquito is coextensive in geographical distribution with mala- 

 ria ; that is, while Anopheles mosquitoes may exist in non- 

 malarial regions, indigenous malaria has never or hardly ever 

 been found when Anopheles was proved by repeated search to 

 be absent. 



(2) That standing water which has long been associated 

 with malaria is dangerous simply because it breeds mosquitoes. 



(3) That excavations and upturned soil are dangerous 

 because they favor standing water. 



(4) That the eradication of Anopheles mosquitoes from 

 a neighborhood by effectual drainage of the breeding pools, 

 or other methods, has been found again and again to eradicate 

 malaria. 



Finally, to the question, Are there other modes of producing 

 malaria besides actual inoculation by infected blood or the bite 

 of an infected Anopheles mosquito? Science at present can not 

 definitely answer No. But there seems every reason to believe 

 that Anopheles is, at least in 99 per cent, of the cases, the only 

 practical source of the disease. 



How many species of Anopheles are inculpated is also not 

 yet fully known. In G. M. Giles's last monograph (just out), 

 on the Anophelincc, he announced some thirty new species of 

 Anopheles besides the forty-four or forty-five so far described. 

 Of these seventy odd species, only about fifteen, or, at most, 

 twenty, have been rigidly connected by scientific experiment 

 with malaria. The ten or twenty mentioned, however, are far 

 the commonest, and are practically the source of all the various 

 types of malarial disease. 



No other genus of the CiiUcidcc, except Anopheles, has 

 been experimentally connected with human malaria at all. 

 Immense numbers of experiments with many species of Culex 

 were always negative. A few experiments with the very rare 

 giant mosquito, Psorophora, by myself two summers ago, were 

 also negative. 



The balance of scientific authority tends to show that 

 Anopheles is the definitive host, and the only definitive host, 

 of the parasites of human malaria. 



40 East 58 Street. 



