182 
EXPERIMENTAL PATHOLOGY. 
A practical application of the results I have just mentioned en¬ 
ables us easily to render dogs refractory to rabies. Indeed, we 
can easily understand how the person who experiments may have 
at his disposal rabid viruses attenuated to various degrees of 
strength ; some not deadly, to protect the economy from the 
effects of more active viruses, and those from deadly viruses. 
Let us take an example : The rabid virus of a rabbit, dead from 
trephining, after an incubative stage lasting several days beyond 
the shortest incubation in the rabbit, is taken. The incubative 
stage is generally of seven to eight days’ duration after inoculation 
by trephining the most virulent virus. This virus of rabbit 
with a longer incubative stage, is inoculated (always by trephin¬ 
ing) to a second rabbit, and the virus of this to a third. At 
each time, these viruses which become stronger and stronger, 
are inoculated to a dog. This animal is then able to resist a 
deadly virus and becomes entirely refractory to rabies, whether 
by intra-venous inoculation, or by trephining with the virus of a 
dog with street rabies. 
By inoculation of the blood of rabid animals, in given circum¬ 
stances, I have succeeded in considerably simplifying the opera¬ 
tions of vaccination, and to give to the dog the most marked and 
refractory condition I will soon make known the whole of the re¬ 
quirements relating to this. 
It would be of immense interest both now and until the far 
distant period of the extinction of rabies by vaccination, to be 
able to prevent the development of this affection after the bites 
of rabid dogs. On this point the first experiments I have made 
give me the greatest hopes of success. Thanks to the duration 
of the incubation of rabies after bites, I am justified in believ¬ 
ing that we can certainly indue a subject with refractory power 
before the deadly affection makes its appearance as a consequence 
of the bite. 
Though the first experiments are strongly in favor of this view, 
yet many more are required upon various species of animals be¬ 
fore human therapeutics can reach the audacity of attempting the 
prophylaxy upon man. 
It will easily be understood that notwithstanding the faith I 
