PROTECTIVE INOCULATIONS. 



animal, when inoculated into the dog, no longer produces fatal rabies ; 

 and that dogs so treated are subsequently immune. 



In his address before the International Medical Congress at Copen- 

 hagen (August llth, 1884), after a review of the facts developed during 

 his experimental researches made during the preceding four years, 

 Pasteur gives an account of the test made by a commission, appointed 

 by the Minister of Public Instruction, to determine the efficacy of his 

 method as applied to the protection of dogs. He says that he gave to 

 the commission nineteen dogs which had been rendered refractory 

 against rabies by preventive inoculations. These nineteen dogs and 

 nineteen control animals, obtained from the pound without any selec- 

 tion, were tested at the same time. The test was made upon some of 

 the animals of both series by inoculation with virulent material upon 

 the surface of the brain, and upon others by allowing them to be bit- 

 ten by rabid dogs, and upon still others by intravenous inoculations. 



Not one of the protected animals developed rabies ; on the other 

 hand, three of the control dogs out of six bitten by a mad dog devel- 

 oped the disease, five out of seven which received intravenous inocu- 

 lations died of rabies, and five which were trephined and inoculated 

 on the surface of the brain died of the same disease. In a subsequent 

 report the commission, of which M. Boulley was president, stated that 

 twenty-three protected dogs which were bitten by ordinary mad dogs 

 all remained in perfect health, while sixty-six per cent of the control 

 animals, bitten in the same way, developed rabies within two months. 



In his communication of October 26th, 1885, Pasteur reports his 

 discovery of the fact that the virulence of the spinal cord of a rabbit 

 is gradually attenuated by hanging it in a dry atmosphere, and is 

 finally entirely lost ; also that he had been able to make a practical 

 application of this discovery in the protection of dogs by means of 

 successive inoculations beneath the skin of an emulsion of spinal mar- 

 row attenuated in this way. The first inoculation was to be made 

 with a portion of spinal cord which had been kept long enough to de- 

 prive it of all virulence, and this was followed by daily inoculations 

 with more virulent material, until finally material was used from a 

 cord only a day or two old. 



With reference to his first inoculations in man, Pasteur says : 



" Making- use of this method, I have already made fifty dogs of various 

 races and ages immune to rabies, and -had not met with a single failure, 

 when, on the 6th of July, quite unexpectedly, three persons, residents of 

 Alsace, presented themselves at my laboratory." 



These persons were Theodore Yone, who had been bitten on the 

 arm on July 4th ; Joseph Meister, aged nine, bitten on the same day 



