256 



It is well known in a general way that in 

 one country malaria is more intense than in 

 another, but here we have a means of exactly 

 measuring this difference, and, moreover, in the 

 different parts of any particular district. We 

 may illustrate this by the differences we found in 

 Bengal in an extent of country where, as far as 

 we could judge, the climatic conditions were 

 practically identical, yet we find in the environs of 

 Calcutta the endemic index is o, while in the 

 Duars (at the foot of the Himalayas) it is as high 

 as, seventy-two (Fig. 59). We found, however, 

 that there was one important matter in which 

 the Duars differed from Calcutta, and that was 

 in its Anopheline fauna. Whereas in Calcutta 

 M. rossii was the predominant species, in the 

 Duars M. listont was the commonest Anopheline. 



Again, in the Jeypore district (Madras), we had 

 a district of uniformly high endemic index, fifty 

 to one hundred, and here we found an Anopheline, 

 P. jeyporensis, which we had not encountered 

 elsewhere, so that the view seemed tenable that 

 the high endemicity of these districts was 

 dependent on their special Anopheline fauna. To 

 test to what extent species was concerned in 

 determining endemicity, we then made use of 

 atfother more exact method, viz., determining by 

 dissection whether any difference occurred amongst 

 the different species in the percentage of infected 

 specimens : we were able to carry this out in the 

 case of M. rossii and M. culicifacies. We caught 

 these species in the same huts in the same villages 

 at the same time, and determined by actual dis- 

 section the percentage of glands infected with 

 sporozoits. The results were most striking, and 



