516 HYDKOPHOBIA 



constitute the great work of Pasteur ; and everything points to 

 a micro-organism being the cause. The organism, whatever it is, 

 is, in its infective form, probably very small, as it can pass 

 through the coarser Berkefeld filters, and also occasionally 

 through the coarser Chamberland candles. Evidence that it is 

 the organism itself which passes through, is found in the fact 

 that when an animal dies from infection with the filtrate, a 

 small portion of its central nervous system will originate the 

 disease in a fresh animal. Judging from our knowledge of 

 similar diseases we would strongly suspect that it is actually 

 present in a living condition in the central nervous system, the 

 saliva, etc., which yield what we have called the hydrophobic 

 virus, for by no mere toxin could the disease be transmitted 

 through a series of animals, as we shall presently see can be 

 done. A toxin may, however, be concerned in the production 

 of the pathogenic effects. Remlinger found that death with 

 paralytic symptoms sometimes followed the injection of filtered 

 virus, but that the nervous system of the dead animals did not 

 reproduce rabies. He explains this occurrence by supposing that 

 the filtrate contained a toxin but not the actual infective agent. 

 The resistance of the virus to external agents varies. Thus a 

 nervous system containing it is virulent till destroyed by putre- 

 faction ; it can resist the prolonged application of a temperature 

 of from - 10 to - 20 C., but, on the oher hand, it is rendered 

 non-virulent by one hour's exposure at 50 C. Again, its 

 potency probably varies in nature according to the source. 

 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 undoubtedly 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 



