338 READINGS IN BIOLOGICAL SCIENCE 



throughout their entire attacks. They also remained perfectly well. The 

 experiment was repeated a third time with the same results. This experi- 

 ment explained why people had been able to wash the bedding and cloth- 

 ing of yellow fever patients without taking the disease. It absolutely cleared 

 the fomites of suspicion. 



HOW A HOUSE IS INFECTED WITH YELLOW FEVER 



Since it was proved that a house could not be infected with the yellow 

 fever by fomites, the question now arose: "How does a house become in- 

 fected?" To answer that question with certainty, a second building was 

 erected similar to the first, except that it was well ventilated. It was screened 

 so that mosquitoes could not get in or out. The room was then divided 

 by a wire netting that extended from top to bottom and allowed the air to 

 pass freely from one side to the other. Therefore, if there were any germs 

 or "miasms" floating in the air that could cause yellow fever they would 

 be found on both sides of the screen. To show that the building was un- 

 infected, four men slept in it for two weeks, two on each side of the netting. 

 They remained perfectly well. "Now," said Major Reed, "I am going to 

 infect one side of this room with yellow fever and not the other side." He 

 took out the two men from one side and set free there 15 Aedes mosquitoes 

 that had previously bitten yellow fever patients. John J. Moran then en- 

 tered the mosquito-infested space for a short time on three successive days. 

 Four days after his first visit John Moran came down with a well-developed 

 case of yellow fever, from which he recovered. During each of his visits 

 two other nonimmunes remained in the building on the other side of the 

 wire netting, and they slept there for 18 nights. They remained in perfect 

 health. Therefore Reed concluded that as the air on both sides of the wire 

 screen partitions was exactly the same, it must have been the presence of 

 contaminated mosquitoes that infected the side in which Moran contracted 

 yellow fever, and the absence of mosquitoes that made the other side per- 

 fectly healthful. 



HOW AN INFECTED HOUSE IS DISINFECTED 



Walter Reed then said: "Now that I have shown you a house infected 

 with yellow fever, I will demonstrate how it can be disinfected and ren- 

 dered safe." He caught the mosquitoes and put them back in their jars. 

 Then he said that the building was disinfected. The two men returned to 

 the side that had been infected and they and the two on the other side con- 

 tinued to live there in perfect health. 



PASSING SENTENCE ON THE VILLAIN 



The experiments of Camp Lazear proved beyond the shadow of doubt 

 that the Aedes aegypti mosquito is a carrier of yellow fever. Apparently 



