86 
JAMES LAW. 
action of the swine-plague virus, by being first brought under 
the influence of the chemical products resulting from the 
growth of this virus in the system. We have, further, another 
pig treated in the same way with the products of an ordinary 
putrefactive fermentation in a pork infusion, which had been 
similarly devitalized by heat, but this fails to secure the same 
immunity, and this pig suffers severely from swine-plague 
when made to cohabit with a victim of that disease. Later, 
this pig and the two others successfully resist two successive 
inoculations with swine-plague virus, while a fourth pig in¬ 
oculated with this same virus sustains a considerable, but not 
» ' 
a fatal attack. 
“ The experiments, it is true, are limited in number and 
liable to the objection that the results may have been acci¬ 
dental coincidences, yet, so far as they go, they support the 
theory that the chemical product of the swine-plague germ, 
when deprived of its living microphytes, affects the system so 
as to render it for the future insusceptible to the attacks of 
such germs. When taken in connection with the fact that 
swine-plague rarely recurs in the same individual, that, as in 
the case of other diseases that attack the same animal but 
once, the most rational explanation is that it is the deleteri¬ 
ous products of the disease germ and not the germ itself that 
affects the system so as to secure this immunity ; and finally, 
considering that in the closely allied disease of anthrax Tous- 
saint has secured a similar insusceptibility by an identical 
process, it is altogether reasonable to suppose that we are here 
furnished with a system of prevention which, if carried into 
general practice, would reduce our present losses from swine- 
plague to a comparatively insignificant figure.” 
The report goes on to show the danger of popularizing 
this method, since all the fatal diseases of hogs vulgarly but 
mistakenly known as hog-cholera would be resorted to for the 
protective ptomaines, with unsatisfactory results. Also that 
protection from all these varied fatal swine diseases would be 
vainly sought by the use of the ptomaines of swine-plague. 
Then follow summaries of needful precautions and of the mani¬ 
fest advantages and disadvantages of the method. 
