1884—1885 393 



As the number of cases observed became larger, he felt a 

 growing conviction that hydrophobia has its seat in the nervous 

 system, and particularly in the medulla oblongata. ''The 

 propagation of the virus in a rabid dog's nervous system can 

 almost be observed in its every stage,'* writes M. Roux, 

 Pasteur's daily associate in these researches, which he after- 

 wards made the subject of his thesis. "The anguish and fury 

 due to the excitation of the grey cortex of the brain are followed 

 by an alteration of the voice and a difficulty in deglutition. 

 The medulla oblongata and the nerves starting from it are 

 attacked in their turn; finally, the spinal cord itself becomes 

 invaded and paralysis closes the scene." 



As long as the virus has not reached the nervous centres, it 

 may sojourn for weeks or months in some point of the body; 

 this explains the slowness of certain incubations, and the fortu- 

 nate escapes after some bites from rabid dogs. The a priori 

 supposition that the virus attacks the nervous centres went very 

 far back ; it had served as a basis to a theory enunciated by Dr. 

 Duboue (of Pau), who had, however, not supported it by any 

 experiments. On the contrary, when M. Galtier, a professor 

 at the Lyons Veterinary School, had attempted experiments in 

 that direction, he had to inform the Academy of Medicine, in 

 January, 1881, that he had only ascertained the existence of 

 virus in rabid dogs in the lingual glands and in the bucco- 

 pharyngeal mucous membrane. ''More than ten times, and 

 always unsuccessfully, have I inoculated the product obtained 

 by pressure of the cerebral substances of the cerebellum or of 

 the medulla oblongata of rabid dogs." 



Pasteur was about to prove that it was possible to succeed 

 by operating in a special manner, according to a rigorous tech- 

 nique, unknown in other laboratories. When the post-mortem 

 examination of a mad dog had revealed no characteristic lesion, 

 the brain was uncovered, and the surface of the medulla 

 oblongata scalded with a glass stick, so as to destroy any 

 external dust or dirt. Then, with a long tube, previously put 

 through a flame, a particle of the substance was drawn and 

 deposited in a glass just taken from a stove heated up to 200° C., 

 and mixed with a little water or sterilized broth by means of a 

 glass agitator, also previously put through a flame. The 

 syringe used for inoculation on the rabbit or dog (lying ready on 

 the operating board) had been purified in boiling water. 



Most of the animals who received this inoculation under the 



