108 INSECTS AND MAN 



munity and good health, and they watched our experiment 

 with keen interest; but when we advised them to adopt 

 our simple and easy method of protection, they shook their 

 heads and invariably answered, ' Wait till the rains come.' 

 The poor creatures spoke from cruel experience, because a 

 drenching is always followed by relapse in those who have 

 latent malarial organisms. More than once we were 

 thoroughly soaked by torrential showers, but no fever 

 ensued, because we had no malarial parasites in our system 

 that a chill might rouse into activity. 



" Long experience in the Roman Campagna and in other 

 malarial regions of Southern Europe has taught that the 

 most dangerous time for contracting malaria is during the 

 evening twilight and at dawn. This fact agrees perfectly 

 with the feeding habits of the mosquitoes of the genus 

 Anopheles peculiar to these regions. We proposed there- 

 fore to retire an hour before sunset, and not again to leave 

 our mosquito-proof hut until an hour after sunrise. But 

 we very soon found that it was not necessary to retire so 

 soon as an hour before sunset, because the Anopheles 

 appeared very punctually a few minutes after sunset and 

 disappeared again a few minutes after sunrise." 



During the whole of this time the two scientists and 

 their companion remained in perfect health ; by day they 

 went about the country quite freely, but always retired to 

 their hut in the evening, before the mosquitoes became 

 active. The hut (Plate IV.), which was made of yellow fir, 

 consisted of five rooms, one of them serving as laboratory 

 and mess room. The windows and double door were pro- 

 tected with copper wire gauze, whilst the whole of the 

 interior was painted white, so that stray mosquitoes could 

 be easily detected ; as a further precaution, each bed was 

 provided with mosquito curtains. 



So much for the proof of the mosquito malaria theory 

 by negative inference. With regard to the direct positive 

 proof, Dr Sambon says that " the mosquitoes were collected 



