11 



(the orgaa from which he almost invariably made his cultures) can not 

 be regarded as incontestible proof that the '' swine-plague " germ has 

 had no existence in the afflicted hogs which have fallen under his 

 observation, and affords no evidence that this last-named disease does 

 not occur in Nebraska. 



The Commission regard their experiments concerning immunity as 

 inconclusive and more or less indefinite^ yet it seems to be evident that 

 there is a certain degree of protection against artificial acquisition of 

 hog cholera possessed by the Nebraska pigs, which had been inoculated 

 and which had recovered from the natural disease, the latter appearing 

 to be slightly less protected than the former. Furthermore, the feeding 

 experiments above mentioned appear to indicate that the hog can be 

 artificially protected against the action of virulent living cultures even 

 to a greater degree by Introducing the germs into the stomach than by 

 subcutaneous inoculation. 



It is the opinion of the Commission that the only proper way to test 

 I)ractically the real value of artificial protection against ^' hog cholera'^ 

 is to expose the supposed protected pig to the natural acquisition of the 

 disease under ordinary conditions, such as exist among a herd of ho^s 

 suffering from the natural disease. It is a well known fact, brought to 

 light by recent investigations concerning the nature of infectious 

 diseases, that immunity or protection from a second attack, whether 

 artificial or natural, is not absolute, but only relative in degree. There 

 is no known infectious disease either of man or beast capable of pro- 

 ducing by one attack a degree of protection which is surely and abso- 

 lutely effective against a second attack. 



Experience has abundantly shown that animals that are naturally 

 or artificially protected can be practically overwhelmed by enormous^ 

 doses of the germs of the disease, and thus be made to suffer a recur- 

 rent attack, which may even be fatal. Furthermore, the method of 

 artificial inoculation and the mode of natural acquisition of the disease 

 also seem to materially influence the degree of x>rotection acquired. 

 For example, it is well known that Pasteur has put into extensive 

 practical application in France his method of producing artificial im- 

 munity against anthrax in sheep and cattle by subcutaneous inocula- 

 tion ; and it is also well known that the losses by this disease among^ 

 herds where the inoculation has thus been performed have been re- 

 duced 90 per cent, as the result of inoculation ; yet Koch, as an oppo- 

 nent of Pasteur, concerning the practical value of protective inoculation^ 

 has demonstrated beyond cavil that cattle in which subcutaneous in- 

 oculation has been practiced are but little protected against the ac- 

 quisition of the disease experimentally by way of the digestive appa- 

 ratus. 



It is the opinion of the Commission that disinfection as a general 

 practical means of preventing the enormous annual losses from diseases 



