YELLOW FEVER. 439 



occur, shows that it contains epithelium from the 

 mouth and bacteria of various forms. This is not 

 surprising when we remember that every drop of 

 saliva swallowed is charged with a variety of these 

 minute plants. To decide whether any one of 

 these bears a causal relation to the disease, would 

 require extended culture-experiments, and the 

 administration of a pure culture to man himself, as 

 a test of specific pathogenic power, unless satis- 

 factory evidence can be obtained that some one of 

 the lower animals is susceptible to the disease. 



A more recent claim to the discovery of the 

 yellow fever germ is that made by Dr. Freire of 

 Brazil. 



I quote again from the " Medical News " (July 

 7, 1883, p. 13): 



" Dr. Freire recognizes in the blood of j^ellow fever 

 patients a cryptococcus to which he has given the specific 

 title of Xanthogenicus. In the phases of its development 

 it appears as minute points, or as large round cells with 

 grayish or fringed margins, and bright transparent 

 centres. Besides these there are occasionally seen trans- 

 parent granulations, aggregated in a yellowish matrix. 

 A gramme of blood charged with these organisms, from 

 a yellow fever patient, was injected into the veins of a 

 rabbit, which died in a quarter of an hour with tetanic 

 convulsions. ... At the autopsy visceral congestions 

 were found, similar to those seen in persons dead of 

 yellow fever, and the blood was found to contain the 

 cryptococcus which was present in that which had been 

 inoculated. 



" A gramme of the blood of this rabbit was injected 



