174 
D. P. YONKERMAN. 
To prevent a disease is, to the man of science, to be able to 
recognize the conditions on which its origin and development de¬ 
pends, and to be competent to submit these conditions to such 
modifications as will nullify their tendency to produce the mor¬ 
bid conditions or hinder their operation. This necessitates a 
study of many subjects, and demands the exercise of the highest 
faculties of the human mind. And the suppression of a spread¬ 
ing disease requires, in addition to this knowledge, an acquaint¬ 
ance with the laws upon which its extension depends, and the best 
means for counteracting their effects. 
But, though possessed of all this knowledge, the sanitarian, 
from a variety of circumstances, may not be able to utilize it 
wholly, or even in part, for the public benefit; so that the ad¬ 
vantages to be derived from his studies may be partially or alto¬ 
gether lost, unless he can obtain the concurrence and aid of those 
who are in a position to frame laws and enforce their observance, 
with a view to applying this knowledge efficiently, and, of course, 
beneficially. 
The assistance of the law-maker has, therefore, to be invoked, 
and to the political economist or legislator, who must in the first 
instance draw his inspirations from the sanitarian, preventive 
medicine, as applied to the domesticated animals, must appear a 
subject of the greatest moment. To be able to avert the ravages 
of an impending epizooty, may be to preserve his country from a 
great crisis; and to suppress a disease which destroys thousands 
of creatures—more particularly if the agricultural wealth of a 
State, consisting chiefly of useful animals, constitutes a large por¬ 
tion of its capital—is not only to spare it the direct loss which 
such a malady causes, but often to relieve it from anxiety and 
hardship. 
For it must be remembered that the majority of the maladies 
which come under the cognizance of veterinary sanitary science, 
more or less directly affect every branch of agriculture, and that 
the damage they cause is not limited to the immediate pecuniary 
loss and inconvenience attending the inefficiency or death of those 
/ affected, but extends to the breeding and multiplication of ani¬ 
mals, embarrasses one or more branches of commerce, and gener- 
