1901) MICROSCOPICAL JOURNAL. 37 
best culture medium to be 2 per cent alkaline pepton so- 
lution with 1 or 2 per cent of gelatin, as recommended by 
Yersin and Wilson. .The bacillus develops under condi- 
tions of aerobiosis and anzrobiosis. In glucose-contain- 
ing media it does not form gas. No indol is formed. Or- 
dinarily the culture-medium is acidified by the develop- 
ment of an acid that persists for three weeks or more. By 
frequent passage through animals of the same species, the 
bacillus increases very much in virulence. Curiously 
enough, however, the observations of Knorr, substantia- 
ted by Yersin, Calmette, and Borrel, show that the bacil- 
lus made virulent by frequent passage through mice,is not 
increased in virulence for rabbits. Mice, rats, guinea-pigs 
rabbits, monkeys, dogs and cats are all susceptible to in- 
oculation. During epidemics, thé purely herbiverous an- 
imals usually escape, though oxen have been known to die 
of the disease. When blood, lymphatic pulp, or pure cul- 
tures are inoculated into them, the animals become ill in 
from one to two days, according to their size and the vir- 
ulence of the bacillus. Their eyes become watery, they 
begin to show disinclination to take food or to make any 
bodily effort, the temperature rises to 41.5°C., they re- 
main quietly in a corner of the cage, and die with convul- 
sive symptoms in from two to seven days. If the inoc- 
ulation was intravenous, there is no lymphatic enlarge- 
ment, but if it was subcutaneous, 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 has found that frogs are susceptible to the dis- 
ease. Wyssokowitz and Zabelotny 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 inaculture of the bacil- 
lus, the puncture being made in the palm of the hand or 
sole of the foot, the monkeys died in from three to seven 
