( clx-xv ) 



thai after residing for some time in a hot climate the relative 

 proportions of various waste products secreted internally and 

 externally alter. The composition of the perspiration alters 

 and the individual becomes less attractive to mosquitoes than 

 when newly arrived. In spite of the fact that new-comers 

 perspire more freely than natives, who take things more 

 gently, I believe that mosquitcei are not attracted by such 

 differences in quantity but in the quality of the secretion. I 

 admit nine-tenths of this is conjecture, but it is the only 

 working hypothesis that I can get that will explain the facts. 

 1 have tested it for two years now. There seems to be no 

 doubt whatever that a new arrival to the tropics is more 

 worried and more bitten by mosquitoes. It is not a matter 

 of suffering more from the bites. I still swell and suffer from 

 any bite, but there are places where I can now sit in comfori 

 where 1 was continually bitten on my first arrival; and I 

 find that new-comers still suffer when sitting alongside me at 

 these same places, so that there has been no reduction in 

 the number of mosquitoes. 



" Of course I know that the mosquito goes to get blood 

 and not perspiration as in the case of the butterflies discussed 

 in the P.E.S., but still it must be the scent of the perspira- 

 tion that originally attracts them to their prey. Tabanids 

 are blood-suckers, yet I have seen them attracted to a pair 

 of socks just removed after a hot walk. 



I wonder if some Bio-Chemist could be persuaded to take 

 up the study of the composition of perspiration in relation to 

 climate and mosquito attraction. It seems to me that it 

 might lead to the discovery of some attractive baits for 

 mosquitoes and possibly even for tsetse flies, to which the 

 reasoning' might also apply. 



" I was particularly pleased with the remark in the Pro- 

 ceedings about gout accounting for the non-attraction of 

 butterflies to the perspiration of one individual. I believe 

 gout is due to faulty kidney action, and this would of necessil y 

 have a direct effect on the composition of the perspiration. 



" I should be very glad if you would let me know what 

 you think of this idea. Quite possibly it- has been proposed 

 before, but if so I have not heard of it. If you think it of 



