CONTRIBUTION TO THE STUDY OF SWINE PLAGUE, ETC. 327 
of its virulency and with the toxine of the swin pest. By suc¬ 
cessive passages by rabbits and by pigeons, he has obtained 
such a powerful virulency that a very weak dose (0.01-0.25 cc.) 
injected subcutaneousl} 7- would kill rabbits in from twelve to 
fifteen houis. In heating the virulent blood or the culture at 
57 f° r an hour the microbe was killed, but there remained a 
toxine, which, injected in the vein of the rabbit in dose of 3.5 
cc., 01 8 cc. under the skin would kill him. Selander admits 
that this toxine is the cause of death ; he succeeded in immun¬ 
izing rabbits against the microbe, but not against the toxine, 
with repeated injections of small doses of sterilized blood. 
The attenuation of virulency obtained by Cornil and Chante- 
messe in keeping cultures at 43 0 for thirty days, Selander fails 
to obtain, as the microbe of swin pest dies in twenty-four hours 
at a temperature of 41-41.8° 
In 1891, Smith publishes, under the direction of Salmon, 
a monography on swine plague , analogous to that published 
two years belore on hog cholera. Here, again, the differentia¬ 
tion of the two diseases is made specially by the morpholog¬ 
ical character and the localization of the lesions. In this 
monography are resumed the previous publications of the two 
authors, of which I present again the principal points. The 
microbe of swine plague is smaller than that of hog cholera , 
is immobile, resisting less to various agents, grows less abun¬ 
dantly on various grounds of cultures, not at all on potatoes, 
produces no fermentation of glucosis, no indol; but formed 
phenol. In the pathogenous point of view, Smith recognizes 
an acute form, killing the rabbit with a weak dose in sixteen 
to twenty hours ; a sub-acute form which kills in two to seven 
hours ; and a chronic form characterized by infiltration and 
formation of pus. A point to observe, as we will consider it 
later on in our own experiments, vaccinated rabbits, after in¬ 
oculation of virulent cultures, presented the same symptoms 
of fresh rabbits with the microbe of attenuated form. Among 
animals at the laboratory, rabbits are the most sensitive to the 
virus, then come mice, guinea pigs, pigeons and chickens. 
Pigs are generally refractory to subcutaneous inoculations, 
but most commonly die after an intravenous or intrathoracic 
injection. 
