koch’s method with tuberculosis. 
87 
PRECAUTIONS TO BE OBSERVED. 
“ ist. -See that it is the genuine swine-plague that is being 
dealt with. This is equally necessary as to the disease to be 
prevented and as to the virus which is to be devitalized for 
preventive inoculation. 
“ 2d. The virulent fluid to be devitalized may be the blood 
of a diseased animal, or the liquid exudation into a diseased 
organ, including the lumen of the bowel. In such cases it is 
best taken at the height of the disease rather than from a 
partially convalescent animal, in which the virus may have 
disappeared and the structural changes only may have been 
left. If from a cultivation in pork infusion, that should have 
been prepared with all due precaution against the intro¬ 
duction of air bacteria, and with access to air, but which air 
should not much exceed one-fifth of its bulk. 
“ 3d. In exposing this fluid to heat, that should be carried 
to 140° F. and retained at that temperature for an hour or 
more, until, in short, all indications of life in the contained 
mycrophytes have ceased. 
“ 4th. Swine to be operated on must be kept apart from all 
diseased hogs, infected places and objects, for with the pres¬ 
ence of the living germ in the system the injection of the 
devitalized chemical products only tend to aggravate the at¬ 
tack. For the same reason all inoculated animals showing 
symptoms of a severe attack, and presumably suffering from 
bacteridian infection, in place of the simple intoxication with 
the chemical products, should be at once removed from the 
herd operated on. 
5th. u In inoculating the devitalized chemical products, the 
injection of a small quantity at a time and its repetition at in¬ 
tervals of three days or a week promises to be safer and more 
effectual than one large injection. The injection of ten or 
twenty drops at a time, and its repetition once or twice, would 
probably secure a greater immunity with less loss of condition 
and progress than if a large amount were introduced at once. 
“ 6th. The animals operated on should be carefully guarded 
against infection for three weeks after the last injection of the 
