395 



presented a miljd albuminuric attack after the inoculation, ever experienced 

 any subsequent attack of the disease. 



Nearly all our inoculations were performed upon persons who had 

 come to stay several years in Cuba; only 10 of the 102 left the island 

 before having completed their fourth year, the rest lived from four to 

 twelve years in Havana (a few spent part of that time in Cienfuegos or 

 Matanzas). Only 4 of the total number (less than 4 per cent.) died of yellow 

 fever; 2 of them five and eight months after their inoculations, the 2 

 others after five and six years; none of them had reacted after their in- 

 oculations. Among all the 102, during their entire residence on the island, 

 independently of the attacks attributed to the inoculations, 4 had fatal 

 hemogastric yellow fever, as previously sated; 19 had albuminuric yellow 

 fever, mostly of a mild type, but 4 of them severe with some hemogastric 

 tokens, all recovered; 17 had non-albuminuric yellow fever, and 9 had 

 abortive yellow fever, including 2 who only developed a suspicious 

 ephemeral fever. The remaining 53 never experienced any form of the 

 natural yellow fever during the years which they spent in Cuba after their 

 inoculations. 



I had thought of two ways by which more decided experimental results 

 would be obtained; one way was by applying several contaminated insects 

 at a time ; the other to consist in feeding the mosquito exclusively on sugar, 

 during two or three weeks after they had bitten a yellow fever patient, and 

 only applying them after the lapse of that time to a non-immune. From a 

 careful study of Melier's famous report of the epidemies of St. Nazaire, in 

 1861, I had come to the conclusion that it was in consequence of conditions 

 such as these that the contaminated mosquitoes which had sought shelter in 

 the hold of the Anne-Marie during its trip to St. Nazaire, must have 

 acquired the intense virulence which enabled them to inoculate with fatal 

 yellow fever every person who entered the hold of the vessel after its arrival 

 at that port. It was on these grounds that I wrote, in a paper dated 

 December 31, 1891, the following words: "It is my belief that, while one 

 or two stings from recently contaminated mosquitoes can only occasion in 

 susceptible persons a mild attack or simply confer immunity without any 

 pathogenic manifestations, a severe attack would result from a greater 

 number of such stings and the same might occur in consequence of one 

 single bite from a mosquito which had been fed exclusively on sweet juices 

 during several days or weeks after its contamination, before being allowed 

 to sting another person." 



At that time I still; attributed the increased virulence to the 

 multiplication of the germs which had been retained within the sucking 

 ¡apparatus of the mosquito ; but in 1898 I read before the Academy of 

 Sciences of Havana a paper in which I suggested, as the reason why only 

 the Culex mosquito, alone among its Cuban congeners, has the faculty of 

 transmitting yellow fever, that it has a pathogenic susceptibility for the 



