244 INFECTION AND IMMUNITY 



The question whether malarial fevers can be con- 

 tracted in any other way than through inoculation 

 by infected mosquitoes, or direct experimental inocu- 

 lation with the blood of one suffering from malarial 

 infection, has been submitted to experimental investi- 

 gation, and the answer is in the negative. Formerly 

 it was believed by many physicians that malarial 

 fevers might be contracted by drinking surface water 

 obtained in malarious localities, but there is no ex- 

 perimental evidence in favour of this hypothesis. 

 The first experiment of the nature indicated was 

 made in the summer of 1900, and the results were 

 reported by Manson in September of that year. 



Five healthy individuals lived in a hut on the 

 Roman Campagna since early in the month of July. 

 They were protected against mosquito bites by mos- 

 quito-netting screens in the doors and windows and 

 by mosquito-bars over the beds. They went about 

 freely during the daytime, but remained in their pro- 

 tected hut from sunset to sunrise. At the time Man- 

 son made his report all these individuals remained in 

 perfect health. It has long been known that labourers 

 could come from the villages in the mountainous re- 

 gions near the Roman Campagna and work during the 

 day, returning to their homes at night, without great 

 danger of contracting the fever, while those who re- 

 mained on the Campagna at night ran great risk of 



