140 PASTEUR AND HYDROPHOBIA HI 



blood-poisoning clue to another virus present in the 

 hydrophobic saliva, M. Pasteur tested his rabbits by 

 inoculating dogs with the saliva and blood of the 

 rabbits. The dogs did not develop rabies, and thus 

 M. Pasteur was able to establish the conclusion con- 

 firmed by other observations — that the disease pro- 

 duced in this instance by the inoculation of the rabbits 

 with saliva was not rabies. This is merely an 

 example of the careful method by which it is M. 

 Pasteur's habit to correct and solidly build up his con- 

 clusions. 



The first result of great practical moment estab- 

 lished by M. Pasteur is that not only, as shown by 

 previous experimenters, can rabies be communicated 

 from animal to animal by the introduction of the 

 saliva of a rabid animal into the loose tissue beneath 

 the skin of a healthy animal, or by injection of the 

 same into the veins of a healthy animal, but that the 

 " virus," or poison, which carries the disease resides 

 in its most active form in the nervous tissue of a rabid 

 animal, and that the most certain method of communi- 

 cating rabies from one animal to another is to intro- 

 duce a piece of the spinal cord or of a large nerve of a 

 rabid animal on to the surface of the brain of a healthy 

 animal, the operation of exposing the brain being 

 performed with the most careful antiseptic -methods, 

 so as to prevent blood-poisoning. 



In this way Pasteur found that he could avoid the 

 complications which sometimes result from the pres- 

 ence of undesired poisonous matters — not related to 

 i^abies — in the saliva of rabid animals. 



