HUMAN ANT) ANIMAL VARIOLA*!. 
24 1 
and afforded one more proof that a certain lapse of time must 
ensue before the preservative influence of vaccine comes into 
play. 
However strong and abundant clinical and casual evidence 
may be, it is not always completely convincing, unless supported 
by experimental demonstration, when it is then irresistible. This 
evidence is also fortunately at hand, and in a most exhaustive and 
complete form; and it is very remarkable that, with the excep¬ 
tion of one speaker at the conference (Dr. Cameron), its existence 
does not seem to have been known to those present; at least, this 
may be inferred from the circumstance that it was never alluded 
to, save in the one instance mentioned. That my surmise is not 
very wide of the truth, may be taken for granted, when we read 
of one gentleman saying, in reference to the experiments con¬ 
ducted by my friend, Professor Chauveau, of the Lyons Veteri¬ 
nary School, and briefly summarised by Dr. Cameron, that “ it 
seemed strange that men should, at the present time, go abroad 
to France, to the futile and speculative experiments of a French¬ 
man, and take possession of the inferences he entertained.” Such 
language betokens either ignorance of, or an utter failure to ap¬ 
preciate, the value of the results of these experiments; but then 
this speaker asserted that he had successfully inoculated a large 
number of cows with small-pox virus, and produced vaccinia 
which gave him abundant vaccine lymph. 
In France, as in some other European countries, the origin of 
cow-pox had long been a fruitful subject for discussion and specula¬ 
tion and more than once it had provoked warm debates at the Paris 
Academy of Medicine. In 1863, M. Bouley, then director of the 
Alfort Veterinary School, had re-discovered at Paris the “horse- 
pox” of Dr. Loy, of Pickering—in reality, the “grease” of 
Jenner, Sacco, and others, who believed in the ecpiine origin of 
cow-pox. But M. Depaul, who had also, with Bouley, studied 
this vaccinogenous disease of the horse, was inclined to follow the 
example of Baron and his followers, and to conclude that it and 
other eruptive disorders occurring in animals, and possessing 
analogous characters, were nothing more or less than human 
variola. So it was that he included sheep-pox, and the aphthous 
