106 



■capable without themselves directly having had access to a case 

 yellow fever, of giving the disease to a susceptible individual. Tl 

 explanation has now received the support of an experimental case 

 yellow fever induced by the sting of a Stegomyia fasciata apparent 

 hereditarily infected. This case is reported by Marchoux and Simoi 

 in a paper on "The hereditary transmission of the yellow fever vin 

 in the Stegomyia fasciata," a translation of which we give in appendi: 

 p. 114. 



Against this one positive case we submit the negative results i 

 inoculations attempted in 13 nonimmunes. 



In an endeavor to account to ourselves for the divergence of oi 

 results from that of the French workers we have considered sever 

 factors in the problem, failure to comply with any of which mig 

 readily be productive of negative results. We believe, howeve 

 that our work, so far as we can judge from the details in the 

 paper, closely parallels the work of Marchoux and Simond. Natu 

 ally the first factor which arises for consideration is whether tl 

 mothers of the Stegomyia fasciata used by us for the inoculation < 

 our nonimmunes were infected. Marchoux and Simond state that tl 

 mother of the insect whose sting produced the positive case 

 fever had been made to feed ori several (number not stated) a of the 



mosquitoes were experimentally proved to be infected. In the first the progeny 

 one mother were tried without results upon .three nonimmunes; in the other a lai 

 brood from several mosquitoes was kept in a, breeding jar and was fed upon noni: 

 munes with impunity. 



"During the progress of this bulletin through the press the second report of t 

 French Commission to Rio de Janerio (Marchoux and Simond, Annales de 1' Instil 

 Pasteur, Paris, XX, 2, Jan. 25, 1906, p. 16) came to our hands, giving full details 

 the positive experimental case of yellow fever produced by the sting of a 8tegom\ 

 fasciata apparently hereditarily infected, as follows : 



"Experiment. — A female Stegomyia fasciata born in the laboratory and arriving 

 ., the adult stage January 19 {probably means January 9), 1905, was paired from the £ 

 to the 11th. It stung a yellow-fever patient presenting a severe attack in the seco 

 day of the disease, on the 11th of January, and laid the first batch of eggs Janus 

 17. On the 25th of January it stung another patient in the. second day of the disea 

 who presented an attack of moderate severity, and laid the second batch of ej 

 January 28. This latter batch hatched out from the 3rd to the 4th of February, a 

 the larvse cared for in the laboratory produced perfect insects February 16. 



"Two females from this batch were isolated in tubes and fed with sirup up 

 March 2. At this date— that is to say, 14 days after completing their metamorphos 

 these mosquitoes, were made to sting subject A. This subject, a Portuguese, b 

 arrived in Brazil only a few days before and had never had yellow fever. He show 

 no reaction to this inoculation. After an interval of eight days, March 10, the sa 

 subject was stung a second time by one of the two mosquitoes, the other having ac 

 dentally died. Four days later, March 14, he presented symptoms of yellow feve: 



It will be noted, therefore, that the eggs giving rise to the progeny that apparen 

 caused an attack of yellow fever .were laid by the mother mosquito 17 days af 

 the first and 3 days after the second feed of yellow-fever blood. (Compare ( 

 mosquitoes Nos. 3 and 4, Group II, of Set 1, p. 107.) 



