Contagious Pleuro- Pneumonia of Cattle. 187 



Macroscopic Agglutination. 



The results of a considerable amount of work on the macro- 

 scopic agglutination test for contagious pleuro-pneumonia have 

 already been published by the writer, who was able to demon- 

 strate the presence of agglutinins in the serum of a hyper-immun- 

 ised calf (Calf 1), but could not demonstrate them in the sera 

 of animals infected with contagious pleuro-pneumonia naturally 

 .acquired. Calf 1 had reacted to a primary subcutaneous inocu- 

 lation of active pleuro-pneumonia virus in the tail, and subse- 

 quently received two further subcutaneous inoculations of viru- 

 lent material (one of active pleuro-pneumonia virus, the other 

 •of pure culture) behind the shoulders at intervals of 10 to 12 

 days. Serum from Calf 1 in dilutions up to 1 in 70 caused 

 macroscopic agglutination of a culture of the organism of con- 

 tagious pleuro-pneumonia, while the sera of non-immunised 

 animals used as controls had no agglutining effect upon a similar 

 -quantity of the same culture.^ 



The presence of agglutinins in the sera of hyper-immunised 

 bovines has been confirmed by Titze and Seelemann, (2) who 

 have recently published the results of their experiments in which 

 they were able to demonstrate the presence of specific agglutinins 

 in the serum of a hyper-immunised heifer and of a hyper-im- 

 munised bull. 



While specific agglutinins can be demonstrated in the sera of 

 hyper-immunised cattle, all attempts by the writer to demon- 

 strate the presence of agglutinins in the sera of animals natur- 

 ally infected with contagious pleuro-pneumonia have, until re- 

 cently, been unsuccessful ; the conclusion arrived at by the writer 

 in his previous publication being as follows: — 



" Agglutinins could not be demonstrated, in the sera taken 

 from bovines known to be affected with contagious pleuro- 

 pneumonia, by the usual macroscopic and microscopic methods 

 ■of testing for agglutinins. Therefore an agglutination test ap- 

 parently has no value as a means of differentiating between 

 animals which are, and which are not, affected with the 

 disease."^'' 



4. Loc. cit., p. 183. 



5. Loc. cit., p. 209. 



9 a 



