HOG CHOLERA. 
15 
try by diseased animals. With these facts before us can we say 
the malady is strictly infections and that any one who speaks of 
it as contagious is entirely wrong? It seems to me that such an 
assertion is supremely ridiculous and shows a lamentable ignorance 
of modern classification of disease. 
While writing this 1 have taken a few standard works from my 
shelves at a venture, and every one, including Ziegler’s Lehrbuch 
der pathologischen Anatomic (4th ed.), Fliigge’s Die Mikroor- 
ganismen (2nd ed.), Putz Die Seuchen und Herde Krankheiten, 
and Roll’s Thierseuchen, include all bacterial diseases under the 
general term of “ Infectious diseases.” Ziegler then divides in¬ 
fectious diseases into miasmatic diseases , contagious diseases and 
miasmatic-contagious diseases. Fliigge divides the infectious dis¬ 
eases according to the nature of the parasites causing them into 
contagious obligatory parasites, contagious facultative parasites, 
and non-contagious facultative parasites. 
It is not my intention to insist upon any classification in this 
connection. No student of pathology can be ignorant of the wide 
differences which exist between various standard authors. What 
I desire is to draw your attention from this never ending contro¬ 
versy as to the exact meaning which should be ascribed to the 
words infectious and contagious and to concentrate it upon the 
facts in reference to this particular disease. 
The same author insists in the most positive terms that hog 
cholera is an extra-organistnal infectious disease. In other words 
that the parasite is one the natural habitat of which is the soil, 
that the hog obtains it from the soil and not through contagion, 
and that once planted in the soil this microbe remains there and 
multiplies for an indefinite period. Where are the records of the 
experiments which demonstrate this proposition put forth in such 
emphatic terms ? Have you seen them ? I have not. 
In the laboratory of the Bureau of Animal Industry we have 
plodded along for three years laboriously endeavoring by means 
of experiments to throw some light upon the biological characters 
of this microbe and the conditions under which it may be preserv¬ 
ed. We have observed after many outbreaks that fields and pens 
have been safely used within three to six months after the disappear 
ance of the disease. We have frequently observed the same fact 
