132 JOHNKS DISEASE 



eighth hours following the inoculation. None of the 

 animals showed any evidence of diarrhoea. 



On reviewing the tests carried out on cattle, sheep, 

 and goats, we may at once exclude those with Vaccines 

 Nos. I to 5. These vaccines were prepared from early 

 cultures of Johne's bacillus, and were too weak to 

 cause any definite reaction in the animals. The 

 results obtained with Vaccines Nos. 6 and 7 show that 

 a vaccine made from a good glycerine-broth culture of 

 Johne's bacillus is as reliable a reagent for Johne's 

 disease as tuberculin is for tuberculosis, and, indeed, 

 it would have been surprising had it been other- 

 wise. 



In the case of Johne's disease, it is interesting to 

 note that the maximum temperature was usually 

 recorded before the tenth hour — that is, much earlier 

 than when tubercular animals are tested with tuber- 

 culin. The situation of the disease in the intestine 

 and lymphatic glands might possibly account for this 

 early rise, but a more feasible explanation would 

 appear to be found in the nature of the lesions. 

 Nearly all tubercular lesions are surrounded by a 

 fibrous capsule, or are encompassed by a large quan- 

 tity of lymphocytes, while in Johne's disease the 

 lesions are never encapsulated, and gradually blend 

 with the normal tissue. 



As regards the specificity, we may note that all our 

 tubercular animals that were free from Johne's disease, 

 including some that are not given in the chart, failed 

 to react in the slightest degree to a vaccine prepared 

 from cultures of Johne's bacillus ; while in animals 

 suffering from Johne's disease, whether tubercular or 

 not, a marked reaction was obtained. Exceptions, 

 however, are found, as in very advanced cases, which 

 may fail to react, and we know that this is often the 



