436 
GEORGE FLEMING. 
When vaccination as a protection from sinall-pox began to 
gain ground, as its benefits were becoming more and more evident, 
many of the leading veterinarians on the Continent tried it as a 
protective against sheep-pox; but they soon discovered that vac¬ 
cinated sheep were as susceptible to their own particular variola 
as the unvaccinated. Terrier, Goher, Husson, Yoison, and other 
veterinary surgeons, found that, no matter how successful the vac¬ 
cinations had apparently been, the sheep took the disease, either 
accidentally or experimentally, as readily as before. For this 
reason vaccination is never attempted now, as it does not confer 
immunity from sheep-pox—a curious circumstance with regard to 
inter-variolization among different species of animals. 
^ The contagium of slieep-pox is very. active, as has been al¬ 
ready stated. The observations and calculations of Chauveau 
with regard to the infectiousness of the malady, compared with 
that of vaccinia, tend to prove that animals attacked with sheep- 
pox will infect a hundred times more readily than those affected 
with cow-pox. The sheep-pox lymph also, according to the same 
authority, contains in an equal volume and weight a much more 
considerable number of virulent corpuscles, and is much more 
potent than that of vaccinia. He has shown that if the latter is 
diluted with fifty times its weight of water, inoculation with it is 
uncertain in its result, while the sheep-pox matter may be diluted 
with 1500 times its volume of water before it is reduced to the 
same condition. He has also demonstrated that the activity of 
this matter, like that of every other virulent substance, resides in 
the solid particles or elementary corpuscles held in suspension in 
the serum, which is not viruliferous; and that an equal quantity 
of sheep-pox lymph contains thirty times more of these particles 
than that of vaccinia. 
It may be remarked that in Australia, Hew Zealand, and the 
American Continent sheep-pox has never been seen, because it 
has not been carried there. Yet human small-pox, imported from 
the western world, is as prevalent in those regions as with us. 
This should be convincing proof that there is no relationship be¬ 
tween the two variolse, so far at least as their contagious princi¬ 
ples are concerned. 
{To he continued .) 
