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body of the non-immune is intended for the accomplishment of its sexual 

 reproduction, and also that the analogy between it and the malaria parasite 

 holds good, with the difference only that the latter accomplishes this act 

 in the anopheles mosquito while the yellow fever germ does so in the 

 human host, the following important inferences may be drawn. 



The minimum number of days (estimated at 10 or 12 by the Yellow 

 Fever Army Board) which must elapse, after the stegomyia has bitten 

 a yellow fever patient, before the infected insect is able to inoculate the 

 disease through its bites, must represent a series of tranformations in the 

 body of the contaminated mosquito, including : 



(a) Introduction of young sporozoits sucked up with the blood of 

 the patient. 



(b) Growth of the sporozoits to adult age. 



(c) Formation of sehizonts and merozoits. 



(d) Formation of gametes. 



While, in the body of the non-immune, counting from the moment of 

 his inoculation by the infected stegomyia, the following stages are likely 

 to take place during the period of incubation : 



(a) Localization of the gametes in appropriate sites. 



(b) Fecundation of the macrogametes by the microgametes of the 

 yellow fever germ. 



(c) Formation of the ookinet and development of the oocyst in 

 appropiate cells (endothelial?). 



(d) Discharge of free sporozoits of yellow fever into the circulating 

 blood (perhaps too small to be recognized with the microscope). 



(e) Development of the toxemic symptoms characteristic of the 

 invasion of yellow fever, in the inoculated non-immune. 



In calling your attention to this correlation of ideas, my object is not 

 to make a display of fanciful conceptions, but simply to comply with my 

 belief that unless we map out for ourselves some working hypothesis of this 

 kind we shall continue groping in the dark, with little hope of completing 

 our knowledge of the yellow fever etiology. 



