YELLOW FEVER. 521 



ments lactose, more actively ferments glucose and sac- 

 charose, but is not capable of coagulating milk. In the 

 cultures a small amount of indol is formed. It strongly 

 resists drying, dies in water at 6o° C, and is killed in 

 seven hours by the solar rays. It can live for a consider- 

 able time in sea-water. 



The bacterium is pathogenic for the majority of the 

 domestic animals. All mammals seem more or less 

 sensitive to the pathogenic action of the bacillus; birds 

 are often immune. Guinea-pigs are invariably killed by 

 either intraperitoneal or subcutaneous injection of o. 1 

 can. White mice are killed in five days; guinea-pigs 

 in eight to twelve days; rabbits in four to five days. 

 The morbid changes present include splenic tumor, hy- 

 pertrophy of the thymus, and adenitis. In the rabbit 

 there are, in addition, nephritis, enteritis, albuminuria, 

 hemoglobinuria, and hemorrhages into the body-cavities. 



The dog is the most susceptible animal. When it is 

 injected intravenously the disease-process that results is 

 almost immediately manifested with such violent symp- 

 toms and such complex lesions as to recall the clinical 

 and anatomical picture of yellow fever in the human 

 being. The most prominent symptom in experimental 

 yellow fever in the dog is vomiting, which begins directly 

 after the penetration of the virus into the blood and con- 

 tinues for a long time. Hemorrhages appear after the 

 vomiting, the urine is scanty and albuminous, or there is 

 suppression, which shortly precedes death. Once grave 

 jaundice was observed. 



At the necropsy the lesions met are highly interesting, 

 and are almost identical with those observed in man. 

 Most conspicuous is the profound steatosis of the liver. 

 The liver-cells, even when examined fresh, appear com- 

 pletely degenerated into fat, this appearance correspond- 

 ing to that found in fatal cases of yellow fever. The 

 same result may be obtained by injecting the liver di- 

 rectly or through the abdominal wall. The kidneys are 

 the seat of acute parenchymatous nephritis, sometimes 



