658 TKANSMISSION OF YELLOW FEVER BY MOSQUITOES. 



from A^cllow-fever patients or recent eadavers into various culture 

 media for the purpose of cultivating any germ that might l)e present. 

 Extended researches of this kind also gave a negative result, which in 

 my final report I stated as follows: 



The specific cause of yellow fever hav« not yet been demonstrated. 



It is demonstrated that micro-organisms capable of development in tlie culture- 

 media usually employed by bacteriologists, are only found in tlie l)lo()d and tissues 

 of yellow-fever cadavers in exceptional cases, when cultures are made very soon after 

 death. 



Since this report was made various investigators have attacked the 

 question of yellow-fever etiology, and one of them has made very 

 positive claims to the discovery of the specific germ. I refer to the 

 Italian })acteriologist, Sanarelli. His researches were made in Brazil, 

 and, singularly enough, he found in the blood of the first case exam- 

 ined by him a bacillus. It was present in large numbers, Imt this case 

 proved to ])e unique, for neither Sanarelli nor anyone else has since 

 found it in such abundance. It has been found in small numbers in 

 the blood and tissues of yellovr-fever cadavers in a certain niunberof 

 the cases examined. But carefully conducted researches by competent 

 bacteriologists have failed to demonstrate its presence in a consider- 

 able pro})ortion of the cases, and the recent researches of Reed, Car- 

 roll, and Agramonte, to which I shall shortly refer, demonsti'ate 

 conclusively that the bacillus of Sanaielli has nothing to do with the 

 etiology of yellow fever. 



So far as I am aware. Dr. Carlos Finla}', of Havana, Cuba, was the 

 first to suggest the transmission of yellow fever by mosquitoes. In a 

 comnmnication made to the Academy of Sciences of Havana, in Octo- 

 ber, 1881, he gave an account of his first attempts to demonstrate the 

 truth of his theory. In a paper contributed to the Edinl)urg jNIedical 

 Journal, in 1S1>4. Doctor Finlay gives a summar}' of his experimental 

 inoculations up to that date, as follows: 



A sunnuary account of the experiments performed by mj^self (and some also by 

 my friend Doctor Delgado) during the last twelve years will enable the reader to 

 judge for himself. The experiment has consisted in first applying a captive mosquito 

 to a yellow-fever patient, allowing it to introduce its lance and to fill itself with 

 blood; next, after the lapse of two or more days, ap plying ,the same mosquito to the 

 skin of a person who is considered susceptible to yellow fever, and, finally, observ- 

 ing the effects, not only during the first few weeks, but during periods of several 

 years, so as to appreciate the amount of immunity that should follow. 



Between the 30th of June, 1881, and the 2d of December, 1893, 88 persons have 

 been so inoculated. All were white adults, uniting the conditions which justify the 

 assumption that they were susceptible to yellow fever. Only 3 were women. The 

 chronological distribution of the inoculations was as follows: Seven in 1881, 10 in 

 1883, 9 in 1885, 3 in 1886, 12 in 1887, 9 in 1888, 7 in 1889, 10 in 1890, 8 in 1891, 3 in 

 1892, and 10 in 1893. The following table will show the length of time during 

 which the "inoculated" resided in Havana (as also some ten or twelve who resided 

 most of the time in Cienfuegos). During this time the inoculated were under obser- 

 vation, so far, at least, as to obtain information about any attack of yellow fever that 



