BUBONIC PLAGUE. 557 



the bacillus made virulent by frequent passage through 

 mice is not increased in virulence for rabbits. 1 



Mice, rats, guinea-pigs, rabbits, monkeys, dogs, and cats 

 are all susceptible to inoculation. During epidemics the 

 purely herbivorous animals usually escape, though oxen 

 have been known to die of the disease. When blood, 

 lymphatic pulp, or pure cultures are inoculated into 

 them, the animals become ill in from one to two days, 

 according to their size and the virulence of the bacillus. 

 Their eyes become watery, they begin to show disinclina- 

 tion to take food or to make any bodily effort, the tem- 

 perature rises to 41. 5 C, they remain quietly in a corner 

 of the cage, and die with convulsive symptoms in from 

 two to seven days. If the inoculation was intravenous, 

 there is no lymphatic enlargement, but if it was sub- 

 cutaneous, the nearest lymph-nodes are always enlarged, 

 and, in cases with delayed death, suppurated. The 

 bacilli are found everywhere in the blood, but not in very 

 large numbers. 



Devell 2 has found that frogs are susceptible to the 

 disease. 



Wyssokowitz and Zabolotmy 3 found monkeys to be 

 highly susceptible to plague, especially when inoculated 

 subcutaneously. When so small an inoculation was 

 made as a puncture with a pin dipped in a culture of the 

 bacillus, the puncture being made in the palm of the 

 hand or sole of the foot, the monkeys always died in 

 from three to seven days. In these cases the local edema 

 observed by Yersin did not occur. They point out the 

 interest attaching to infection through so insignificant a 

 wound and without local lesions. 



According to Yersin, an infiltration or watery edema 

 can be observed in a few hours about the point of inocula- 

 tion. The autopsy shows the infiltration to be made up 

 of a yellowish gelatinous exudation. The spleen and 



1 Ann. de V Inst. Pasteur, July, 1895. 



* Centralbl. f. Bakt. u. Parasitenk., Oct. 12, 1 897. 



3 Ann. de I Inst. Pasteur, Aug. 25, 1897, xi.,8, p. 665. 



