M. Pasteur’s Experiments on Rabies. 171 
in the animals so inoculated, either hypodermically or by 
trephining—an infallible method of communicating rabies at 
first hand. It created a refractory condition of the animal 
against the disease, 7.e. it was protective. The attenuated 
monkey virus was increased in intensity by successive trans- 
missions through the rabbit and guinea pig, until it became 
even more powerful than the first-hand virus of the dog, and 
was invariably attended by fatal results in the latter animals. 
Thus, there was a descending scale through the monkey, and 
an ascending scale through the rabbit. The dog was found 
to completely resist the most intense form of the virus 
(raised to the highest point by several transmissions through 
the rabbit) when he had been previously inoculated by each 
of the samples of virus in succession. It is a significant fact 
that the lengthened period of latency supposed to accompany 
the disease is very rarely observed in experimental inocula- 
tion; and this should be borne in mind in conjunction with 
the immunity of the Australasian colonies from any invasion 
of rabies, and dispose us to regard with suspicion the state- 
ments of excessively prolonged incubation. 
Some pathologists are inclined to doubt whether the virus 
experimented with by M. Pasteur was really rabific. How- 
ever, a Commission was appointed at his request, by the 
Minister of Public Instruction, to compare the results of the 
inoculation from a rabid dog of a number of dogs treated 
by the attenuated virus, with those of the inoculation of 
an equal number of other dogs not previously protected ; 
and the names of M. Bouley, M. Paul Bert, M. Tisserand, 
and Drs. Beclard, Vulpian, and Villemin, form a sufficient 
guarantee for the conduct of the investigation. 
So far as the experiments by this Commission have yet 
gone, they have completely sustained M. Pasteur’s position. 
Twenty-three healthy dogs, previously inoculated with M. 
Pasteur’s prophylactic virus, were bitten by rabid dogs, and 
otherwise subjected to the strongest virus of rabies. Of 
nineteen others, not protected by M. Pasteur’s method, six 
