258 MICROBIOLOGY 



tuberculous individuals, who should exhibit no signs of irrita- 

 tion from the same procedure. The recent tests of this method 

 in the human subject have given a variety of results and 

 reactions have been obtained in a considerable number of in- 

 dividuals who appeared to be perfectly healthy and who had 

 no history of tuberculous infection. The view has been ex- 

 pressed that this reaction may take place in healed cases of 

 tuberculosis as well as in active ones, due to the fact that the 

 conjunctiva and possibly skin have been sensitized by some 

 previous infection, however slight. If it is demonstrated that 

 this reaction occurs simply as the result of anaphylaxis it 

 would not indicate the presence of active tuberculosis. 



This method of applying tuberculin has been tested in 

 cattle by McCampbell and White 2T and others but it was found 

 not to be very satisfactory. 



Intradermal test. Moussu and Mantoux 28 injected tu- 

 berculin into the skin and produced in tuberculous animals a 

 local oedema and swelling which began in a few hours and 

 reached its maximum in forty-eight hours ; this indicated a 

 reaction. This method eliminates the necessity of taking tem- 

 peratures. Ward and Baker 2!) found this method to be accu- 

 rate in a large percentage of many cases tested by them and to 

 be practicable for range cattle. 



The subcutaneous injection of tuberculin is the only 

 method at present that can be relied upon in testing dairy 

 cattle. The other procedures are still in the experimental 

 stage so far as cattle are concerned. 



Theory for the reaction of tuberculin. The use of tu- 

 berculin has demonstrated three distinct and interesting 

 phenomena: First, a marked sensitiveness of the tuberculous 

 individual and a comparative indifference of the healthy body 

 to it. Second, a distinct thermal reaction of the tuberculous 



27 McCampbell and White. Jour. Exp. Med., Vol. X (1908) p. 232. 



28 Moussu and Mantoux. Trans. 6th. International Congress on 

 Tuberculosis, Vol. IV (1908) p. 821. 



29 Ward and Baker. Proceedings Am. Vet. Med. Asso., 1910, p. 

 291. 



