220 THE ECONOMIC IMPORTANCE OF ANIMALS 



in the Canal zone, where the mosquito (stegomyia) which carries 



yellow fever exists. 



This is due to the 

 experiments during the 

 summer of 1900 of a 

 Commission of United 

 States army officers, 

 headed by Dr. Walter 

 Reed. Of these men one, 

 Dr. Jesse Lazear, gave up 

 his life to prove experi- 

 mentally that yellow fever 

 was caused by mosquitoes. 

 He allowed himself to be 

 bitten by a mosquito that 

 was known to have bitten 

 a yellow fever patient, 

 contracted the disease, 

 and died a martyr to 

 science. Others, soldiers, 

 volunteered to further test 

 by experiment how the 

 disease was spread, so 

 that in the end Dr. Reed 

 was able to prove to the 

 world that if mosquitoes 

 could be prevented from 

 biting people who had 

 yellow fever the disease 

 could not be spread. The 

 accompanying illustration 

 shows the result of this 



Notice the difference in the number of yearly knowledge for the city of 

 deaths from yellow fever before and after TT TV,. TT 



the American occupation of Havana. Havana. For years Ha- 



vana was considered one 



of the pest spots of the West Indies. Visitors shunned this port 

 and commerce was much affected by the constant menace of 



