6 
OLOF SCHWARZKOPF. 
liams. Contagion means to-day what it did two hundred 
years ago, namely, that a healthy animal must come in con¬ 
tact with a diseased animal to contract a particular disease, 
i. e., the origin of one disease is from the same disease of 
another living animal. This may be a rough definition, but 
it is practical, and no elaborate wording or laboratory wis¬ 
dom can make it clearer or better. I am well aware that 
there is some confusion in regard to the term contagious in 
the English-speaking countries, and I believe that the cause 
of it—at least in the veterinary profession—is largely due to our 
worthy Principal Williams, of Edinburgh, who attempted to 
classify contagious and non-contagious diseases in his standard 
work on the Principles of Veterinary Medicine. But there 
are surely yet, as before, contagious and infectious diseases, 
and our great pathologists still apply both terms in a well- 
defined way. There are instances where it is almost impos¬ 
sible to say whether a disease is contagious or infectious, but 
that is no ground for abandoning one term where both can 
be used with advantage in a majority of cases. If the word 
contagious is used alone it becomes necessary to apply some 
adjective in order to define more clearly the character of a 
disease, hence the invention of the terms “ highly contagious ” 
and “dangerously contagious” which are really alarming 
terms, and which I saw first in that “ highly sensational ” 
pamphlet of the Illinois Live-Stock Commission, in which Dr. 
Williams occupied a prominent place. 
Next Dr. Williams attempts to show that actinomycosis 
is a contagious disease. He enumerates several clinical ob¬ 
servations where “ inter-transmission apparently played a very 
important role.’’ He recites cases seen by him and Dr. Case- 
well, and finds these and others “ strongly suggestive.” But 
that is the most he can say, and he is unable to introduce any 
positive evidence that could bring the much wanted light in 
this important direction. Then he recalls the experiments of 
successful inoculation with actinomyces, which are well 
known to the student of actinomycosis ; he does not mention, 
however, the far more numerous instances where inoculation 
was a total failure, avoiding hereby the consequences which 
do not fit into his theory. 
