THE COMPLEMENT FIXATION TEST 139 



post-mortem examination, in most cases the gut was 

 thickened, and pure cultures of acid-fast bacilli were 

 recovered from the intestines of four of the cases. 



In rabbits experimentally inoculated no difficulty 

 was found in demonstrating the presence of a com- 

 plement fixing antibody, but in the case of fowls all 

 attempts proved unsuccessful. Unfortunately the 

 complement fixation tests, like the agglutination re- 

 actions, proved to be specific within the acid-fast 

 group of bacilli only in a very limited degree. 



Since avian tuberculin has been used as a diagnostic 

 reagent in this disease by O. Bang, Male, Miessner 

 and Trapp, Malm, and others, it was thought advisable 

 to carry out a number of comparative tests with the 

 immunity reactions described above. These experi- 

 ments, however, gave no indication that Johne's 

 bacillus is more closely allied to the avian tubercle 

 bacillus than to the human and bovine types. From 

 the results obtained, it appears highly probable that 

 neither the agglutination nor the complement fixation 

 reaction will prove of much value as a practical diag- 

 nostic method in Johne's disease. As in tuberculosis, 

 so, too, in Johne's disease ; the inoculation of a diag- 

 nostic vaccine has been shown to be a far more delicate 

 test, and, what is perhaps of still greater importance, 

 it is more specific, and at the same time easier to 

 perform. 



