FIGHTING THE INSECTS 



reason he did not attend. I was asked to make the opening 

 address. In deference to Mesnil, I spoke especially of the ad- 

 mirable work done by the Pasteur Institute, instancing particu- 

 larly the fundamental discovery of the malarial organism by 

 Laveran; also the work of Marchoux and Salimbeni against 

 Yellow Fever in Rio di Janeiro and of that of the brothers 

 Sergent on Malaria in Algeria. I spoke more or less historically 

 and wound up with some rather extensive remarks about the 

 housefly, as I had at that time only recently published my book 

 on this insect. Dr. Nuttall was the next speaker, and in the 

 intensive discussion that followed, the housefly was almost the 

 only creature mentioned. The last to speak was Dr. C. V. 

 Chapin, the health authority of Rhode Island, who rather threw 

 cold water on the importance of the housefly by stating that its 

 importance as a carrier of typhoid in well-sanitated cities was 

 by no means proved, and that we should have more laboratory 

 demonstrations. He further stated that a close mathematical 

 study of the spread of typhoid in cities should be made on the 

 same general lines as the mathematical studies on the spread 

 of malaria by Sir Ronald Ross. 



I was called upon to close the discussion, and I at once tried 

 to overcome the impression made by Dr. Chapin. I instanced 

 Washington as a well-sanitated city in which there could be 

 no doubt as to the importance of the housefly in the spread of 

 typhoid. I called attention to the human excrement deposited 

 in alley-ways during the hot summer nights in Washington, 

 and of the swarming upon these excreta by houseflies in the 

 immediate neighborhood of the open windows of kitchens and 

 dining-rooms, especially in the lower portions of the city. I 

 showed that it had been proved that a definite per cent, say five, 

 of persons who had recovered from typhoid were chronic car- 

 riers, and that therefore a certain definite proportion of these 



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