THE NATURE OF THE AMERICAN SWINE PLAGUE. 
295 
While we may not know the specific exciting cause with re¬ 
gard to a given disease, if we know the means by which it acts, 
the places in which it exists, which constitute the (so called) sec¬ 
ondary, or supporting, or extending causes, we may prevent the 
ravage of such a disease, without in reality having attained any 
exact idea of the real nature of the specific cause, other than that 
it is of a contagious or infectious nature, as the case may be. 
Let us endeavor to apply these principles to swine-plague. 
In my communication upon the “ Etiological Moment ” in 
this disease—the micro-organism—I took occasion to call atten¬ 
tion to the fact “ that the American swine-plague is an infectious 
and not a contagious diseasethat in reality “ it is a specific 
septicaemia, of extra-organismal origin,”—that is, that it is due to 
a specific micro-organismal element, which finds its primary and 
original locus and means of development in conditions entirely 
outside of the porcine organism. 
I consider the establishment of the true nature of swine- 
plague of infinitely more importance than the discovery of its 
specific, inciting cause—more important even than the discovery 
of a practically possible means of prevention by an artificial 
vaccine. 
Up to this time, all investigators in this country have pro¬ 
nounced the swine-plague to be a “ contagious ” disease. That 
opinion is unequivocally wrong. Being wrong, it is not to be 
wondered at that all attempts at its prevention have so utterly 
failed. 
Law says: 
“ This disease may be defined as a specific contagious fever of 
swine .”—Report of the Department of Agriculture, 1878, p. 379. 
JDetmers says: 
“ Swine-plague is a disease sui generis ; it is communicated 
by direct (contagion) and indirect infection.”— Ibid, p. 332. 
Salmon says: 
“ This disease is contagious, and in the majority of cases may 
be traced to contagion.”— Report, 1880-’81, p. 13. 
Again Salmon says: 
“ The demonstration of the contagiousness of the disease has 
