462 
DR. WILLEMS. 
least so far as it concerns pleuro-pneuraonia, for the inoculation- 
disease is not communicable except by re-inoculation. My ob¬ 
servations on this point are numerous; during the seventeen 
years when inoculation was extensively practiced, I do not know 
of a single example of contagion arising from an inoculated 
animal. 
IV. 
Exudative pleuro-pneumonia is a disease of the bovine spe¬ 
cies, and is not communicable either to other animals or to man, 
by either cohabitation or inoculation. My numerous observations 
on this subject have already been related. 
Facts noticed by myself and by many other observers confirm 
this truth. Animals of all species, especially swine, have been 
fed with the cadaveric remains of pneumonic animals. They 
were placed in permanent contact with diseased subjects; they 
have been inoculated with the exudat of the lung. I have made 
these experiments on goats, sheep, horses, pigs, rabbits, birds, and 
never did I obtain positive results. 
There was even a popular belief, that the emanations of the 
entire goat constituted a prophylactic against against epizootic 
pleuro-pneumonia, and many have adopted the custom of placing 
one of these animals in their sheds, but without any advantage in 
the point of view of protection to cattle. 
“ Each parasite,” says Mr. Chenier, “ has its organism of 
predilection, outside of which it does not find, or does it im¬ 
perfectly, its conditions of existence, growth and multiplication. 
Transported to an improper medium, it dies like a seed in an 
unfertile soil.” 
“ If to those characteristics of parasites, we compare those of 
virulency, we are brought to the conclusion of a striking analogy. 
As the parasites, viruses have their organism of predilection, out¬ 
side of which they cannot live or grow. The virus of foot and 
mouth disease, for instance, dies out when introduced into the 
equine organism.” 
V. 
Before finishing, I believe it advantageous to make some 
recommendations to those who will inoculate. 
