INOCULATION AS A PREVENTIVE OF SWINE DISEASES. 
73 
thrax. While therefore it may be perfectly practical to pre¬ 
vent by inoculation those diseases in which the contagion 
does not multiply outside of the body, and with which the 
attack is caused by a small quantity of virus floating in the 
air or adherent to the wood-work of buildings, it may be 
much more difficult or impossible to prevent that other class 
ot diseases to which hog cholera belongs, and which are 
caused by germs that multiply freely in water, in the soil, and 
in moist organic matter, and which are consequently taken in¬ 
to the body in enormous quantities, especially by swine. 
There is another very important consideration which bears 
upon the practicability of preventing swine diseases by inocu¬ 
lation. Hogs inoculated with hog cholera virus do not re¬ 
ceive the slightest degree of protection from any other dis¬ 
ease. As there are at least two contagious diseases of hogs in 
this country, both of which are widely scattered and fatal, we 
cannot hope by any single inoculation to prevent all the losses 
caused by contagious diseases of swine. To inoculate for two 
diseases would double the expense, and this would be a very 
serious objection to such a method of prevention. The exis¬ 
tence of two diseases has been very vigorously denied, but 
the conclusions of the Bureau of Animal Industry on this 
subject have now been confirmed not only by the Board of 
Inquiry appointed to consider this question, but also by Pro¬ 
fessor Welch, the eminent pathologist of Johns Hopkins Uni¬ 
versity. In the future, therefore, the conclusions as to the 
economy of preventing swine diseases by inoculation must be 
based upon the assumption that there are at least two dis¬ 
eases, each of which will require a special inoculation for its 
prevention. 
This brings us to the final test which must be applied to 
all methods of prevention, and that is their economic results. 
We will now consider inoculation from this point of view. 
Leaving out of consideration for the present the many rea¬ 
sons for believing that inoculation is a dangerous operation, 
and that it does not do what is claimed for it in the way of 
prevention, we will compare the cost of preventing hog 
cholera by this operation with the amount of the loss caused 
by this disease. 
