THE NATURAL HISTORY OF BOMBAY MALARIA. 397 



malaria parasites and M. rossi quite free of infection. It has also 

 been shown that the former anopheles is present not only in the 

 Frere Road area but in lesser numbers in very many parts of the 

 Oity, and wherever it occurs inquiry demonstrates the existence of 

 malaria among the population. This being so, it becomes neces- 

 sary to learn as much as possible about this particular species of 

 mosquito, in order that measures may be taken for its control, in 

 the hope that the spread of malaria in the City may be prevented. 

 But many people are sure to ask the question — " how can ive be 

 certain that by talcing steps to suppress or reduce the numbers of N. 

 stephensi ire may really influence malaria in Bombay?" The 

 answer to this question depends primarily upon the reply which 

 may be given to certain other questions : — 



(1) Whether or not malaria can be conveyed by any other 



agenc}^ than mosquitoes ? 



(2) Whether any kind of mosquito other than those belonging 



to the anopheles family can contract malaria and transit 

 it again to man ? 



(3) Whether all species of anopheles mosquitoes are danger- 



ous or whether only certain species can act as natural 

 carriers of malaria ? 



In reply to question (1) we may point out that we have conclu- 

 sive evidence that malaria parasites can be conveyed from an 

 infected person to a healthy one by the agency of anopheles 

 mosquitoes, and there is not one atom of evidence to show that 

 malaria is contracted in any other way than by the bite of an in- 

 fected anopheles. Thus it is a question of demonstrated fact against 

 pure speculation. 



In regard to question (2) it may be remarked that at present all 

 the evidence is in favour of the conclusion that anopheles mosqui- 

 toes alone are responsible for the spread of human malaria, no one 

 having as yet brought forward a single observation incriminating 

 any other family of mosquitoes. 



In regard to question (3) it may be pointed out that the balance 

 of evidence is in favour of the conclusion that different species 

 of anopheles mosquitoes are not equally dangerous ; and that 

 while some species carry malaria readily others do so with difficulty 



