ii4 



Mosquitoes 



did not transmit the infection. But Simond and 

 Marchoux did actually transmit yellow fever to a 

 voluntary patient with the aid of 

 a mosquito produced from an egg 

 laid by a virulent mosquito. They 

 say that the mosquitoes can thus 

 be infected at birth, and the germ 

 passes through the different stages 

 of the insect's life cycle in a virulent 

 condition if the egg is laid by a 

 mosquito which, after having been 

 infected, but before ovipositing, 

 goes through the twelve days nec- 

 essary for the proper incubation of 

 the fever organism. 



The French doctors do not fail 

 to make about this very important 

 Fig. 23.— Egg of experiment the reservation that it 

 Stegomyia calopus, is the only one, and, in conse- 

 quence, cannot be considered as 

 definitely demonstrative. But even 

 if such infection happened only 

 rarely, the knowledge of its 

 possible occurrence is nevertheless important as ex- 

 plaining the sudden epidemics of yellow fever which 

 break out mysteriously with no imaginable importa- 

 tion of cases or of infected mosquitoes. While an 

 isolated test, made in an infected locality, does not 

 absolutely satisfy the very exacting demands of 

 science, the known ability of the scientists, the high 

 character of their previous work, and the caution with 

 which the experiment was conducted, all go to sup- 



(enlarged about 114 

 times). Originally 

 published in Boys 

 and Girls. 



