190 0. G. Heslop: 



Twenty-three different sera obtained from animals affected 

 with pulmonary lesions of contagious pleuro-pneumonia, the 

 presence of the disease being verified by post-mortem examina- 

 tion at the time that the blood samples were taken, have been 

 submitted to agglutination tests set up in the above manner, and 

 in each instance marked agglutination has been the result. 



On comparing the results of the agglutination tests of these 

 23 positive sera with the post-mortem findings of the animals 

 supplying them, it has been found that the more acute cases of 

 contagious pleuro-pneumonia yield a serum which has a higher 

 agglutination titre than that from cases in which the disease has 

 become chronic and where encapsulation of the lung lesion has 

 taken place more or less completely. Even in these latter chronic 

 cases, in no instance in this series of tests had there been failure 

 to produce agglutination in dilutions of 1 in 133. In the more 

 acute cases, with one exception, agglutination occurred in dilu- 

 tions of 1 in 400, while in two such cases agglutination occurred 

 in dilutions of 1 in 750. The one exception referred to above was 

 Number 143, the serum of an animal affected with the disease 

 in an acute form, but which serum had a final agglutination titre 

 of 1 in 133 only. It would therefore appear that a serum with 

 a high agglutination titre points to an acute infection, but, in view 

 of the one exception quoted above this cannot be stated as an in- 

 variable fact, but only as a general rule. 



In addition to the agglutination tests of 23 different known 

 positive sera, tests have been made with 18 different sera ob- 

 tained from animals which were found on post-mortem exam- 

 ination to be free from lesions of contagious pleuro-pneumonia. 

 These known negative sera all showed agglutination in dilutions 

 of 1 in 20. Thirteen of them showed agglutination in dilutions 

 of 1 in 40, while five of them showed slight agglutination in 

 dilutions of 1 in 80. None of them showed any recognisable 

 agglutination in dilutions of 1 in 100. 



A complete list of the sera tested and a table of the reactions 

 obtained with each is appended, together with an indication of 

 the post mortem findings on slaughter of the animals supplying 

 the test sera. 



