760 MODE OF SPREAD OF INFECTIVE DISEASES. 



to control, and does not sufficiently guarantee the degree 

 of virulence. Further, the whole process of protective 

 inoculation against rabies completely differs from 

 former protective inoculations for small-pox, anthrax, 

 symptomatic anthrax, and swine fever, and also from 

 the experiments made on dogs with the rabic virus, and 

 which served as a proof of the utility of the method, 

 for the people which were inoculated by Pasteur were 

 already infected by the virulent disease. In all 

 the former protective inoculations which might be 

 thought to be analogous, the preventive means were 

 employed before the infection, and experience has taught 

 us that inoculation with vaccine lymph, for example, 

 has no effect if infection with variola has occurred before 

 the vaccination was performed. In like manner the 

 dogs experimented on by Pasteur, with regard to which 

 accurate numbers have been published, were not infected 

 before the protective inoculation. Pasteur mentions, 

 however, that he has attempted subsequent protective 

 inoculation on dogs which had been previously bitten or 

 infected with virulent material ; but accurate numerical 

 details of these most important experiments have not 

 been given, and hence the suspicion arises that in these 

 experiments the result obtained has been as little con- 

 stant and certain as those which have followed the in- 

 oculations on infected individuals. 



A more thorough scientific study of the matter in 

 various directions would, therefore, have been at all 

 events desirable before the method was introduced into 

 practice. It is very possible that the method in its present 

 form, being so difficult of control, may, if employed ex- 

 tensively and by less experienced hands than those cf 

 Pasteur and his assistants, lead to many serious mishaps. 

 General value In conclusion, neither the inoculation for rabies, nor 



of protective , -i ,-1 , ' . . , 



inoculations. tne otner modern protective vaccinations, represent the 

 ideal of a satisfactory prophylaxis against the infective 

 diseases. Even the valuable vaccination for small-pox 

 has not been generally introduced without difficulties, 

 and yet in the case of variola we have to do with a 

 disease which, on account of the number and resisting 



