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Chapter XX 



THE RELATION OF SPECIES OF ANOPHELINAE TO 

 MALARIAL ENDEMICITY 



Species undoubtedly play an important part in 

 the development of blood parasites in the mosquito. 



Proteosoma, for instance, develops in certain 

 species of Culex, e.g., C. nemorosus was used by Koch 

 in Europe. It does not, however, develop in certain 

 species of Taeniorbyncbur (S. P. James). 



The malaria parasite does not develop in species 

 of Culex, Taeniorhyncbus, Stegomyia, or other blood- 

 sucking flies, e.g., Phlebotomus, Simulium, etc. In the 

 case of Culex fatigans placed under absolutely identical 

 conditions with Anophelines, no sign of zygote formation 

 occurs on the second or third day. 



Similarly with regard to Filaria, it is only in 

 certain species of Culicidae that certain species of 

 Filar ia will develop, thus Ce. ar gyro tar sis is an efficient 

 host for F. bancrofti, but inefficient for F. demarquaii. 



The malarial endemicity or endemic index may be 

 defined as the percentage of infected children (under 

 ten years of age) in any district, and represents the 

 liability of immigrants to contract malaria. 



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 differ- 

 ence, 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 



