INSECTS IN RELATION TO DISEASE 



325 



the slightest connection between the vomits and excretions of the 

 patients and the infection of new cases. 



In the other building a volunteer allowed himself to be stung by a 

 mosquito that had drawn blood from a patient some two weeks earlier. 

 The volunteer had been in quarantine for two weeks, to make sure that 

 he was not infected at the time he first came into the building. The 

 bedding and other utensils were thoroughly sterilized. On the fourth 

 day after being stung he developed symptoms of the disease. Other 



Fig. 154. Camp Lazear 



In this building was conducted that part of the yellow-fever experiments which proved 

 that the disease is not transmitted by infected clothing etc. The cabin consisted of 

 a room, 14 by 20 feet, with two small windows facing south, closed with wire screens. 

 Heavy wooden shutters excluded the sunlight. Entrance was through a small vesti- 

 bule on the same side as the windows, protected by a wooden door and a screen door 

 and separated from the main room by a screen door, to make perfectly certain that 

 no mosquitoes could get in. This house was kept closed during the daytime and had 

 a temperature of from 92° to 95° F. It was occupied for twenty nights by three 

 American volunteers, and the test was repeated twice 



volunteers, on the other side of the screen, breathing the same air but 

 not stung by mosquitoes, remained unaffected. Ten or more individuals 

 contracted yellow fever as a result of receiving bites from mosquitoes 

 that had previously bitten sick persons, but not one who stayed on the 

 other side of the screen was infected. In the course of the experiments 

 Dr. Carroll and Dr. Lazear also became sick, the latter dying as a result. 

 The parasite that causes yellow fever was discovered in 19 18 by the 

 Japanese scientist Noguchi, working at the Rockefeller Institute. 



