226 CONTAGIOUS DISEASES. 



of preparing his vaccine, which at first was transmitted from 

 the dog to the monkey, in which animal the virulence became 

 enfeebled after each transmission, until it became too attenuated 

 to convey the disease, and was used as a preventive vaccine. 

 Now, however, Pasteur inoculates a rabbit, in which the period 

 of incubation is always short, through a trepan in the skull, 

 having discovered that after successive inoculations from one 

 rabbit to another virulence becomes intensified, and the period 

 of incubation shortened, until it is reduced to six days. The 

 virus then has attained its highest degree of virulence, and is 

 called " virus fixe." The spinal cord of a rabbit, having had 

 this intensified rabies, having been suspended in a jar at a tem- 

 perature of 73° F. in an atmosphere kept dry by the presence of 

 potash, gradually loses its virulence. The opinion that rabies 

 could not be transmitted after an animal had been dead twenty- 

 four hours, or after rigor r,iortis had been completely established, 

 has been found to be erroneous ; for it is now placed beyond 

 doubt that virulence may be retained for a considerable time, 

 provided putrefaction be prevented. The activity of tlie virus is 

 also destroyed by various disinfectants, as such 1-1000 corrosive 

 sublimate solution, 5 per cent, solution permanganate of potash, 

 50 per cent, alcohol ; but 15 per cent, alcohol is said to preserve 

 it for several days, and large doses are rendered innocuous by 

 being rendered acid, alkaline, or putrefactive. The virus of 

 rabies is contained in its most concentrated form in the saliva 

 of the rabid animal ; but it by no means follows that other 

 parts of the diseased animal are free from its presence ; indeed, 

 direct experiments have determined that the virus is present in 

 the blood, flesh, and other parts of the rabid animal. The virus 

 of the rabid skunk, wolf, and hysena appears to be more virulent 

 and prompt than that of the dog. 



It was at one time believed that the virus of rabies was in- 

 nocuous when the bite was inflicted by any of the herbivora. 

 Observation on accidental cases had led to this belief, and direct 

 experiments seemed to confirm its correctness. Girard, Vatel, 

 Huzard, Dupuy, Lafosse, and others failed to transmit the disease 

 from the herbivora to the dog. Professor Coleman, Sir Astley 



