CONTRIBUTION TO THE STUDY OB' SWINE PLAGUE, ETC. 333 
The cultures and the virulent blood are sterile after 
being exposed from one hour to an hour and a half to the tem¬ 
perature of 58° in a water bottle. I name a length of time a 
little longer, because Thave sometimes obtained cultures of 
hog cholera in sowing blood rich in clots, sterilized at 58° in 
half an hour. On this occasion I have observed that hog 
cholera resists heat more than swine plague . 
The sterilization with thymic acid is very simple; it is 
sufficient to place several small crystals of thymol in a tube 
filled with virulent blood. The microbes are destroyed after 
a length of time, which varies, and here again hog cholera has 
resisted longer (three weeks to one month), while the mi¬ 
crobe of swine plague was destroyed after eight to fifteen 
days of contact. I have also obtained the complete sterili¬ 
zation of the blood of swme plague by adding ten drops of a 
solution of formic aldehyd. at 2 per cent, of 10 cc. ol liquid. 
As for the vitality of the cultures, an ensemenced bouillon 
which keeps to the eture for more than three months is gen¬ 
erally sterile. Upon gelosis the survie seems to last longer, 
an abundant culture of hog cholera more than ten months old 
having furnished a virulent culture with a new planting. 
Preserved in drawn glass tubes, closed with the lamp, away 
from the light, the microbes remain alive and virulent for a 
much longer length of time. A drop of blood of swine 
plague , kept for eleven months, has killed a mouse in twenty- 
four hours; the blood from her heart has given abundant 
culture. 
From what precedes, the two microbes that I have ex¬ 
amined can be differentiated morphologically by the fol¬ 
lowing characters: the bacillus of hog cholera presents, as 
compared with that of swine plague , viz.: First, larger di¬ 
mensions. Second, a more rapid growth upon gelatine and 
a more abundant culture upon gelosis. Third, the growth 
upon potatoes. Fourth, the formation of gas in culture of 
glucosed bouillon in connection with chloride of lime. Fifth, 
a greater resistance to physical and chemical agents. The 
three last characters are the most important. 
