20 6 
II. Ennur (Madras) 
Number 
dissected 
Number 
with sporozoits 
Percentage 
M. culicifacies 
- 
69 
6 
8*6 
M. rossi 
- 
364 
0 
0 
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, 
