124 JOHNE^S DISEASE 



tubercle bacilli. It may, however, be noted that the 

 bull was a very advanced case, and that Vaccines 

 Nos. I and 5 were weak. 



From the results obtained with Vaccine No. i, it is 

 clear, as might have been expected, that to obtain 

 a specific reagent for pseudo-tuberculous enteritis the 

 tubercle bacillus must not be incorporated in the 

 medium. It will be seen from the table that a timothy- 

 grass bacillus vaccine caused no rise of temperature 

 in normal animals or in animals suffering from tuber- 

 culosis or pseudo-tuberculous enteritis, although, being 

 filtered through a porcelain filter, the vaccine was 

 probably weakened. It will be seen also that Vaccines 

 Nos. 4 and 5, which were prepared by growing Johne's 

 bacillus in media containing the timothy-grass bacillus, 

 caused no reaction in experimental or in control 

 animals. 



It may seem surprising that no reaction was obtained 

 with Vaccines Nos. 4 and 5 in the animals affected with 

 Johne's disease; but, in point of fact, the negative 

 results might have been anticipated, as 'the greater 

 part of the bacillary emulsion used was obtained from 

 growths on solid media, the bacilli being made into an 

 emulsion without any previous grinding. It must also 

 be remembered that infected animals rarely, if ever, 

 show a rise of temperature during the course of the 

 disease, so that a more concentrated vaccine might be 

 required for Johne's disease than for tuberculosis. If, 

 as is held by many authors, the tuberculin reaction is 

 an anaphylactic phenomenon, and is in no way related 

 to the ordinary temperature changes found in a tuber- 

 culous animal, then the absence of a temperature in 

 Johne's disease should be no guide to the quantity of 

 specific vaccine likely to be necessary to produce 

 a thermal reaction. 



