2o6 

 II. ENNUR (MADRAS) 



Undoubtedly then, under natural conditions, the 

 species is here a very important factor. 



Again, under artificial conditions (feeding experi- 

 ments), we found that there was a difference in the 

 number of zygotes found in the stomach as the result 

 of feeding. 



The species which appeared to be most active 

 were : 



M. culicifacies 

 N. stephensi 

 N. theobaldi 



Those in which zygote formation seemed less 

 abundant were : 



M. rossi 

 M. turkhudi 

 M. barbirostris 



It should be noted, however, that in these experi- 

 ments M. rossi became infected, while in nature it has 

 never been found infected by us. 



There are, moreover, many considerations which 

 lead to the conclusion that in nature all species of 

 Anopheline are not equally concerned in the trans- 

 mission of malaria. 



We may have countless numbers of M. rossi, as 

 in Calcutta (environs), and yet a malarial index of o, 

 and this appears to hold good in Madras, Bombay, 



