106 Mosquitoes 



posedly infected clothing, bedding, or other articles 

 can not possibly convey the disease, that only the bite 

 of an infected mosquito or the subcutaneous injec- 

 tion of blood taken from the general circulation dur- 

 ing the first and second days of the fever can possibly 

 transmit the infection and in the face of recent demon- 

 strations of the fact in New Orleans and elsewhere, 

 there actually remain physicians who still cling tena- 

 ciously to the notion — I almost said superstition — 

 that the disease may be carried otherwise than by the 

 mosquito. Not long ago I talked with one who still 

 insists, though he admits the mosquito theory, that 

 it may also be conveyed after the manner of typhoid. 

 He is a fine physician, but he never studied zoology. 

 In the light of recent scientific developments, it seems 

 to me that a short course in invertebrate zoology, 

 with particular reference to parasitic forms, is an es- 

 sential to the making of an up-to-date doctor. 



Yellow fever has never been contracted, so far as 

 experiment goes, from air, soil, water, or any other 

 infected media, nor even from dead bodies. This all 

 agrees with the protozoan theory, and it is conclu- 

 sively proved that yellow fever is not contagious. 



The work of the French Commission at Petropolis, 

 a town at an elevation of three thousand feet at a 

 distance of twenty-five miles from Rio de Janeiro, is 

 a good illustration of the case. Nobody can find 

 Stegomyia in Petropolis, and nobody ever developed 

 yellow fever there spontaneously. The French 

 Commission produced it there, however, by the bites 

 of infected insects brought from Rio. There is yellow 

 fever continually in Rio, and also plenty of the mos- 



