A CHAPTER ON INSECTS 131 



shelters after sundown was sufficient to protect 

 against infection. Experiments on a large scale were 

 also carried on in the most infected districts of the 

 swampy campana of central Italy. Camps were 

 constructed in these unhealthy districts and the 

 persons experimented upon were divided into two 

 groups that lived under similar conditions except 

 that one group was protected in well-screened rooms, 

 though freely exposed to the fogs and vapors from 

 the marshes. The other group was unprotected by 

 screens. The results were spectacular. Those pro- 

 tected from the bites of mosquitoes contracted no 

 fever while those that were exposed to mosquito bites 

 were stricken with malaria. 



As a further experiment infected mosquitoes were 

 sent from Rome to London and there allowed to bite 

 healthy person who were by this means infected with 

 malaria fever. Thus was forged the last link in the 

 chain of evidence connecting the Anopheles mosquito 

 with the transmission of malarial fever. 



This was the first demonstration of direct connec- 

 tion between insects and the transmission of a 

 specific disease. Although suggestions that insects 

 act as disease carriers are found scattered through 

 scientific literature for a number of years, neverthe- 



