470 HYDROPHOBIA. 



variation may occur in nature. Thus, while the death rate 

 among persons bitten by mad dogs is about 16 per cent, 

 the corresponding death rate after the bites of wolves is 

 80 per cent. Here, however, it must be kept in view 

 that, as the wolf is naturally the more savage animal, the 

 number and extent of the bites, i.e., the number of channels 

 of entrance of the virus into the body, and the total 

 dose, are greater than in the case of persons bitten by dogs. 

 As we shall see, alterations in the potency of the virus can 

 certainly be effected by artificial means. 



The Prophylactic Treatment of Hydrophobia. Until 

 the publication of Pasteur's researches in 1885, the only 

 means adopted to prevent the development of hydrophobia 

 in a person bitten by a rabid animal, had consisted in the 

 cauterisation of the wound. Such a procedure was un- 

 doubtedly not without effect. It has been shown that 

 cauterisation within five minutes of the infliction of a rabic 

 wound prevents the disease from developing, and that if 

 done within half an hour, it saves a proportion of the cases. 

 After this time, cauterisation only lengthens the period of in- 

 cubation ; but, as we shall see presently, this is an extremely 

 important effect, and undoubtedly in every case of a suspected 

 bite, cauterisation ought to be practised. 



The work of Pasteur has, however, revolutionised the 

 whole treatment of wounds inflicted by hydrophobic animals. 

 Pasteur started with the idea that, since the period of 

 incubation in the case of animals infected subdurally from 

 the nervous systems of mad dogs, is constant in the dog, the 

 virus has been from time immemorial of constant strength. 

 Such a virus, of what might be called natural strength, is 

 usually referred to in his works as the virus of la rage des 

 rues, in the writings of German authors as the virus of die 

 Strassivuth. Pasteur found on inoculating a monkey subdur- 

 ally with such a virus, and then inoculating a second monkey 

 from the first, and so on with a series of monkeys, that it 

 gradually lost its virulence, as evidenced by lengthened 

 periods of incubation on subdural inoculation of dogs, until it 

 wholly lost the power of producing rabies in dogs, when intro- 



