A CHAPTER ON INSECTS 135 



These methods have cleared malarial regions of 

 the sources of infection and, in particular, in the 

 Panama zone, conditions were established that made 

 possible the construction of the Panama Canal. 



Yellow Fever. There is no more interesting and 

 inspiring chapter of biological achievements than 

 that of the struggle and the triumph of demon- 

 strating the nature and the means of conveyance of 

 yellow fever. This is one of the greatest medical 

 discoveries of any century. It is usually designated 

 the greatest American medical discovery but, it 

 stands in parity with another medical advance orig- 

 inating in the United States, viz., painless surgery, ac- 

 complished by means of the administration of ether. 



Yellow fever is a rapidly spreading, most dreaded 

 and very fatal disease of tropical and sub-tropical 

 climates. Havana and Gulf ports have repeatedly 

 been the scene of this great scourge. Up to 1898 it 

 was believed to be communicated by infected articles 

 of clothing, bedding, furniture, etc., and, further, 

 that it was commonly introduced into the body 

 through respiration. But, thanks to the investiga- 

 tions of Walter Reed and his associates, it is now 

 thoroughly demonstrated that yellow fever is trans- 

 mitted through the bite of a mosquito and in no 



