Transmission 541 



patient suffering from typhus fever, and developed the disease 

 eighteen days later. In 1907 Otero* endeavored to induce the dis- 

 ease in human beings by inoculation. In one out of four attempts 

 he was successful. 



Experiments with a not infrequently fatal malady made upon 

 human beings being immoral and inexpedient, it became necessary 

 to find some animal susceptible to the disease, with which further 

 experiments could be prosecuted. 



In 1909 Nicolle f succeeded in producing the disease in a chim- 

 panzee by inoculating it with human blood. Later { he was able to 

 transmit the disease from the chimpanzee, and still later from human 

 beings, to Macacus sinicus by inoculating with human blood. In 

 1909 Anderson and Goldberger were successful in transmitting 

 the disease to monkeys, by inoculating them with human blood. 

 Other workers corroborated these results, and thus it became clear 

 that the suspicion that the disease was infectious was correct, 

 and that the infectious agent was in the blood with which it could 

 be carried over to new men and animals and reproduce the disease. 

 Later Nicolle, Couer and Conseil|| were able to transmit the disease 

 to guinea-pigs. 



In Mexico, Gaveno and Girard** were able to carry the infection 

 through 1 1 transplantations from guinea-pig to guinea-pig, and still 

 find it infective for monkeys. 



Still, however, the micro-organism could not be found. Two 

 additional problems therefore became important for solution. 

 First, what was the nature of this virus that could not be found, 

 second, how did it naturally pass from patient to patient? 



In October, 1910, Nicolle, Couer and Conseilff instead of working 

 with artificially defibrinated blood, permitted the blood to coagulate 

 spontaneously, then passed it through the most porous kind of a 

 Berkefeld filter, and successfully infected one out of two monkeys 

 injected with the filtrate. After other series of experiments, these 

 investigators came to the conclusion that the serum of artificially 

 defibrinated blood, when filtered, was always without infective 

 power, and that of spontaneously coagulated blood, commonly 

 so, and that hence, though the virus of the disease is a filterable virus, 

 it consists of organisms so large as to be commonly held back by the 

 coarsest Berkefeld filters. It may be too small to be visible never- 

 theless, at least to such methods of observation as are now in vogue. 



In regard to the transmission of the disease the investigators had 

 before them the usual exemption of physicians, nurses, attendants 



*"Mem. pres. a 1'Acad. de Med. de Mex.," 1907. 



f "Ann. de 1' Inst. Pasteur," 1910, xxiv. 



J"Compt.-rendu Acad. d. Sciences de Paris," 1910. 



"Public Health Reports," 1909, xxiv, p. 1941. 



|] "Ann. de 1'Inst. Pasteur," 1910, xxv, 97. 

 **"Publ. de 1'Inst. Bact. Noc. Mex.," 1910, Nov. 9. 

 ft "Ann. de 1'Inst. Pasteur," 1911, xxv, 97. 



