538 Messrs. Twort and Ingram. Isolating and [Nov. 7* 



replaced by any of the other suitable bacilli or bacillary extracts, the growth 

 of Johne's bacillus does not materially differ from the description given,, 

 except in rapidity and amount, and also in the degree of pigmentation.. 

 When inoculated into fluid media containing a suitable bacillus or bacillary 

 extract, such as ordinary glycerine peptone bouillon, made alkaline, and 

 containing |- per cent, of alcoholic extract of the timothy-grass bacillus, 

 Johne's bacillus grows as tiny whitish grains which settle to the bottom of 

 the tube or flask. These gradually increase in size and number, ultimately 

 reaching the dimensions of a millet seed. There is no general turbidity of 

 the medium ; and with bacilli freshly isolated from the animal body, no film 

 formation. With one of our strains we have recently obtained some growth 

 on the surface of the fluid media, and we expect, in course of time, to obtain 

 a similar growth with the other strains. 



Vaccines analogous to Koch's new tuberculin and Wright's vaccines can 

 also be prepared, but so far we have not had an opportunity of testing the 

 curative effect of these, and, even if successful, the cost of administering 

 such vaccines would prevent their general use. So far, we have been unable 

 to prepare a diagnostic vaccine of sufficient strength to give a positive result 

 with pseudo-tuberculous enteritis, but we anticipate that it will be possible 

 to prepare such a vaccine with the bacillus growing more vigorously on the 

 surface of fluid media. 



Cultures are not easily killed by diffuse daylight, as we have had them 

 standing before a window on the bench for some weeks without any apparent 

 harm. 



Johne's bacillus would also appear to be fairly resistant to the action of 

 disinfectants, since two of our strains were isolated from material which had 

 been subjected to the action of a 1-per-cent. watery solution of ericolin at 

 37° C. for two hours. In this respect it is no less resistant than the tubercle 

 and lepra bacilli. 



Conclusions. 



From the experiments detailed in this paper it is possible to deduce certain 

 conclusions, the most important of which are the following : — 



1. The acid-fast bacillus present in cases of pseudo-tuberculous enteritis 

 of bovines, and known as Johne's bacillus, fails to grow outside the animal 

 body on any of the artificial media at present used by bacteriologists. 



2. The bacillus shows no definite growth on fresh bovine tissue or fresh 

 extracts of bovine tissue removed aseptically and placed into sterile tubes. 



3. There is no evidence that Johne's bacillus grows in symbiosis with an 

 ultra-microscopic virus. 



