1911.] Cultivating the Mycobacterium enteritidis, etc. 



533 



medium containing the human tubercle bacillus, all remained sterile. It is 

 probable that the lesion observed was caused by the inoculation of a large 

 quantity of Johne's bacillus into the actual substance of the gut, the needle 

 of the syringe piercing this when the inoculation was made, and so producing 

 an immediate necrosis of the surrounding tissues before the bacilli were 

 killed by the animal fluids and tissues, or during the process. We consider 

 the above experiment to be negative. 



Six bovines were also inoculated with pure cultures of Johne's bacillus, and 

 it is to be regretted that circumstances did not allow us to perform a larger 

 number of inoculations. We also regret that lack of space prohibits us from 

 describing each in detail. The bare results are given in the accompanying 

 table (p. 534). 



Of the experiments, Nos. 3 and 6 need little comment. No. 3 was killed 

 after a lapse of only six weeks, and No. 6 died after 17 days. In both cases 

 the time was too short for the disease to develop, and in neither of the cases 

 were any of the vaccines tested. Accordingly no conclusions can be drawn 

 from either experiment. 



Of the four remaining bovine experiments, Nos. 1 and 5 developed pseudo- 

 tuberculous enteritis, but also showed some tubercular lesions. Nos. 2 and 4 

 showed no evidence of Johne's disease on post-mortem examination, although 

 No. 2 showed some tubercular lesions. 



In the two bovines which developed Johne's disease the lesions, although 

 definite, were not advanced, and only very few bacilli were found, even in the 

 first bovine, which had been fed 11 months previously. These two experi- 

 ments, taken together with the two negative results, indicate the slow progress 

 of the disease, and, compared with tubercle, the low pathogenicity of Johne's 

 bacillus. But it must be remembered that the experimental animals were 

 fed on hay, bran, oats, and mangolds, as we had no opportunity of turning 

 them out to grass, a procedure which is known to greatly accelerate the 

 progress of the disease. It must also be remembered " that the bacilli may 

 have become less virulent by growing on artificial media, but we believe the 

 diet to be the more important factor in determining the susceptibility to the 

 disease and its rapidity of progress after contraction. We succeeded in 

 recovering Johne's bacillus from the diseased intestine of bovine No. 5, and 

 the cultures obtained were identical in every respect with the culture 

 inoculated. 



The coincident tuberculosis in the two positive cases probably played some 

 part in lessening the resistance to Johne's bacillus. 



The various vaccines which were tested on the experimental animals were 

 also tested on three uninoculated young calves, and on a pedigree bull proved 



VOL. LXXXIV. — B. 2 R 



