PRIZE ESSAY. 
337 
l>y Dutch and English cows, and lias since silently spread over 
nearly the whole eastern sea-board.” * 
ORIGIN. 
The question of the spontaneity or otherwise of its origin has 
been much discussed. Some hold that, given a certain concatena¬ 
tion of circumstances, and it may arise abiogenetically. Others, 
again, equally good authority, maintain that it does not originate 
spontaneously. Practically, it inay be assumed that any manifes¬ 
tations of it seen in these latitudes are due to contagion, mediate 
or immediate. 
This brings us to the question (which has been much discussed) 
of how the disease can be communicated. Granted that it does 
not arise spontaneously, is there any other means of its propaga¬ 
tion than the actual cohabitation of infected and healthy cattle ? 
Many excellent authorities, as Professors Simonds and Brown, 
hold that it can be communicated in no other way. Their experi¬ 
ments, as well as those recently tried by Dr. Burdon-Sanderson at 
the Brown Institute, go far to support this view. This is known 
as immediate contagion. 
On the other hand, such able men and high authorities as 
Fleming, Walley, Williams, and the continental surgeons gener¬ 
ally, strongly combat this view, holding that whatever support 
it may appear to have from experiments, clinical facts prove con¬ 
clusively that the virus can be carried on hay, straw, manure, 
various objects in the stable, etc. This is what is spoken of as 
mediate contagion. The supporters of this opinion point to such 
facts as this: that from a stable in which pleuro-pneumonic cattle 
were kept, all stock were removed, the stable cleansed and kept 
empty for months, and perfectly healthy stock, which had no pos¬ 
sible communication with the disease in any other way, put in; 
these cattle fell victims to pleuro-pneumonia. Such facts as these 
are too numerous and well authenticated to be disputed, and 
leave no doubt of the correctness of those who hold the pos¬ 
sibility of mediate contagion , unless, indeed, we account for these 
outbreaks on the ground of the autogenetic origin of this disease. 
* Professor Law. 
