CULICIDiE : THE ANOPHELES MOSQUITOES G5 



The Anopheline mosquitoes are of the utmost interest 

 to the medical officer because, so far as is known at present, 

 they include the only species that nurse the malaria parasite. 

 Though there is good reason to believe that in every malarial 

 region there are particular species that are specially con- 

 cerned in disseminating the parasite, it would be going far 

 beyond ascertained fact to assert at present that there is 

 any species which is everywhere and at all times, impotent 

 to carry infection. What has been conclusively established 

 so far, in places where Anophelines have been studied to 

 this end is (i) that the parasite in one or other of its forms 

 is found, naturally, in some species and not in others ; 

 (2) that even in the former species it is not found at every 

 season of the year, although the index of infection in the 

 human population may be constant ; and (3) that there are 

 certain species which can not be experimentally infected 

 with the parasite in the laboratory. Every district medical 

 officer, therefore, should endeavour to determine by actual 

 examination of the stomach for zygotes, and of the salivary 

 glands for sporozoites, what local species are naturally 

 infective. The examination should, if possible, be continued 

 through the round of the seasons, and need not be restricted 

 to Anopheline mosquitoes if the medical officer have the 

 proper " cross-bench " mind. 



The removal of the stomach is an easy matter. The 

 mosquito, deprived of unnecessary appendages, should be 

 laid upon a slide, in a drop of tepid saline solution. It is 

 held steady by the front end of its thorax with a needle, 

 while with another needle the dorsal and lateral integument 

 between the last two abdominal segments is scratched 

 through. By a steady pull on the loosened last abdominal 

 segment the greater part of the alimentary canal can be 

 drawn out. 



To remove the salivary glands the mosquito, prepared 

 as before, is held steady by a needle thrust through the 

 muscles in its back, and its head is drawn well forward so as 

 to make the most of its neck. With another needle the 

 dorsal integument of the neck is scraped through, close to 

 the thorax. By a steady pull in a curve forwards and 

 slightly backwards the salivary glands will come away with 



E 



