28 Pasteur's Life and Researches. 



organism, and that, like many others, it produces in the tissues 

 which it invades, a substance whereby, when present in sufficient 

 quantity, its own development and increase are checked, 

 just as the yeast plant ceases to grow in a saccharine liquid 

 when the alcohol which it produces out of the sugar reaches a 

 certain strength. In accordance with this theory, he thinks 

 that the spinal cords of animals that have died of rabies contain 

 both the virus and the antidote (or excretory substance), and his 

 researches have taught him that by drying the cord in a pure 

 atmosphere at twenty degrees centigrade the potency of the 

 virus is diminished, whilst that of the antidote is not propor- 

 tionately lessened. His method of treatment consists in 

 hypodermically injecting carefully sterilised broth in which the 

 spinal cords of rabbits dead of hydrophobia have been crushed 

 and diffused. The first injection is made with a spinal cord of an 

 animal dried for fourteen days after its death ; the second (on 

 the next day) with a spinal cord dried for thirteen days ; the 

 third (on the next day) with a spinal cord dried for twelve days, 

 and so on to the tenth day of injection — that is to say with a 

 progressive decrease in the time of drying the spinal cord. In 

 certain cases, when severe bites had been received, or where a 

 long period had intervened between the bite and the treatment, 

 Pasteur increased the intensity of the latter by successively 

 injecting on the first day what in his milder treatment he took 

 three days for, so that on the seventh day he inoculated the 

 patient with a spinal cord dried only for one day, and this 

 treatment was often repeated ; but he has now rather lessened 

 the severity of the treatment. 



Now, how has this method succeeded ? Between October 

 1885 and the end of Deeember 1886 Pasteur inoculated 2,682 

 persons. Carefully collected statistics have shown at the very 

 lowest estimate five persons in every hundred bitten by rabid 

 animals die. Therefore, if 2,682 persons had not been treated, 

 at least 130 should have died. But. up to the time of issuing 

 the report only 33 had succumbed, and of these seven were 

 bitten by rabid wolves, in three of whom hydrophobic symptoms 

 appeared while under treatment. Including these, then, 97 



