TUBERCULOSIS OF SWINE 147 



temperature is taken only once previous to a tuberculin injection, it is 

 merely a matter of chance if a high temperature, natural to the animal 

 and independent of the action of the tuberculin injection, is not con- 

 founded with and erroneously taken for a tuberculin reaction. The 

 range of the thermal reaction gives no indication of the extent of the 

 tubercular lesions in the animal. Instances are recorded where a second 

 injection of tuberculin has altogether failed to produce a reaction in 

 animals which gave a very decided reaction after the first injection, not- 

 withstanding that the two injections were separated by a very consider- 

 able period of time. This question of the non-reaction to a second 

 injection is a matter for future investigation. Should the foregoing 

 instances be correct, there is nothing to hinder unscrupulous persons to 

 so prepare their animals, that when submitted to a tuberculin test the 

 results are negative, and unhealthy stock left as centres of infection. 



Immunity. At the Ninth International Congress of Hygiene, 

 Behring stated, ' The vaccine of tuberculosis has not yet been found, 

 and that he had hoped to find an active antitoxin with a corre- 

 sponding toxin, but so far he had been unsuccessful. He would even 

 be sceptical as regards such a result had he not found that birds were 

 much more suitable for this kind of research than mammals. With 

 sodium and other reagents, mucin as well as other chemical substances 

 could be extracted from tubercle bacilli. These bodies had nothing 

 to do with the toxin of tuberculosis. If the bacilli were subjected 

 to a temperature of 105 C., freed from fat, and treated with 

 glycerinated water, insoluble albuminous bodies were obtained, which 

 had a virulence twenty times greater. The toxin of tuberculosis was 

 therefore not identical with the primitive substance. The chemical 

 constitution of the toxin was not modified by the operations to which 

 it was subjected. Behring stated the substance which he had isolated 

 was eighty or even one hundred times more virulent than Koch's 

 tuberculin. He had also obtained an antitoxin by passing the virus 

 through a horse in the same manner as was done in the case of 

 diphtheria and tetanus. There was, however, this difference, that in 

 a phthisical patient more than 0'5 c.c. to 1 c.c. could be injected 

 without producing injurious effects, general as well as local. Behring 

 lays it down as a principle that the harmlessness of an antitoxin is an 

 indispensable condition of its practical application, but there are 

 many other difficulties which must be overcome before an antitoxin 

 of tuberculosis can come into use in the treatment of human beings. 

 In bovine animals it is already possible by its means to cure a 

 declared tuberculosis, but even in them one gathers that the remedy 

 at present is somewhat dangerous to life. This, however, as pointed 



