INOCULATION WITH DILUTED VIRUS. 
105 
with the last. The first four recovered, while the remaining six 
died. A month later, an inoculation was made in the other thigh 
of those which had recovered, with a considerable quantity of 
black quarter virus. The resulting symptoms were very mild, 
but not equal with all. Those which suffered the least by the for¬ 
mer inoculation were more intensely affected by the latter. 
The observations of M. Chauveau are undoubtedly very im¬ 
portant if we look upon them as confirming the doctrine of atten¬ 
uation by dilution, but of themselves they are plainly insufficient 
to establish this doctrine with either of the diseases with which 
they are connected. With charbon all the indications must be 
drawn from the last experiment, and this was made with virus of 
doubtful activity. The observation with black quarter virus was 
not a premeditated experiment, there was no intention to inoculate 
with this virus, and, consequently, it cannot carry the weight of a 
genuine experiment. At the same time, viewed in the light of 
my results with fowl cholera, these experiments with charbon and 
the observation with black quarter are sufficient to show that 
these viruses are subject to the general law which my experiments 
were first to demonstrate. 
Still more recently, M. Peuch,* Professor at the Toulouse 
Veterinary ^School, has made experiments in the same direction 
with the disease known as sheep-pox. This is a form of variola 
peculiar to sheep and extremely fatal to these animals. It has 
been combatted in the north of France by inoculation, but in the 
southern departments the losses from this operation were so nearly 
equal to those caused by the spontaneous disease that the practice 
has been about abandoned. As the danger in this disease is prin¬ 
cipally due to the eruption, and as M. Chauveau in his experiments 
with vaccine had granted immunity to cattle by hypodermic injec¬ 
tion of virus without producing any specific eruption, M. Peuch 
conceived the idea that by reducing the number of germs by di¬ 
lution, and injecting the liquid beneath the skin, a similar result 
might be obtained with sheep-pox. His recorded experiments 
have been made with seventeen sheep. Eight were inoculated 
* Iiecueil de Mddecine V6l6rinaire, 1882, p. 977. 
