394 THE LIFE OF PASTEUR 



skin succumbed to hydrophobia ; that virulent matter was there- 

 fore more successful than the saliva, which was a great result 

 obtained. 



" The seat of the rabic virus," wrote Pasteur, " is therefore 

 not in the saliva only : the brain -contains it in a degree of 

 virulence at least equal to that of the saliva of rabid animals." 

 But, to Pasteur's eyes, this was but a preliminary step on the 

 long road which stretched before him ; it was necessary that 

 all the inoculated animals should contract hydrophobia, and 

 the period of incubation had to be shortened. 



It was then that it occurred to Pasteur to inoculate the rabic 

 virus directly on the surface of a dog's brain. He thought 

 that, by placing the virus from the beginning in its true medium, 

 hydrophobia would more surely supervene and the incubation 

 might be shorter. The experiment was attempted : a dog 

 under chloroform was fixed to the operating board, and a small, 

 round portion of the cranium removed by means of a trephine 

 (a surgical instrument somewhat similar to a fret-saw) ; the 

 tough fibrous membrane called the dura-mater, being thus 

 exposed, was then injected with a small quantity of the pre- 

 pared virus, which lay in readiness in a Pravaz syringe. The 

 wound was washed with carbolic and the skin stitched to- 

 gether, the whole thing lasting but a few minutes. The 

 dog, on returning to consciousness, seemed quite the same 

 as usual. But, after fourteen days, hydrophobia appeared : 

 rabid fury, characteristic howls, the tearing up and devour- 

 ing of his bed, delirious hallucination, and finally, paralysis 

 and death. 



A method was therefore found by which rabies was con- 

 tracted surely and swiftly. Trephinings were again performed 

 on chloroformed animals Pasteur had a great horror of useless 

 sufferings, and always insisted on anaesthesia. In every case, 

 characteristic hydrophobia occurred after inoculation on the 

 brain. The main lines of this complicated question were begin- 

 ning to be traceable ; but other obstacles were in the way. 

 Pasteur could not apply the method he had hitherto used, i.e. 

 to isolate, and then to cultivate in an artificial medium, the 

 microbe of hydrophobia, for he failed in detecting this microbe. 

 Yet its existence admitted of no doubt ; perhaps it was beyond- 

 the limits of human sight. "Since this unknown being is 

 living," thought Pasteur, "we must cultivate it; failing an 



