1911.] Cultivating the Mycobacterium enteritidis, etc. 



529 



made up into media, the tubercle bacillus of our original medium being 

 replaced by one or another in quantities of \ per cent. Tubes of each were 

 inoculated with a fresh culture of Johne's bacillus, and the results may be 

 summarised as follows : — 



Dried timothy-grass bacilli gave very good results. 



human tubercle bacilli „ good results, but inferior to the timothy 

 grass bacillus. 



„ bovine „ „ negative results. 



„ swine „ „ „ 



tubercle of uncertain source, freed from wax and fat, gave negative 

 results. 



„ „ „ „ freed from wax, fat, and proteid, gave 



negative results. 



The dried timothy grass bacillus and the dried human tubercle bacillus 

 were found to be equally good when previously autoclaved in normal saline 

 for 30 minutes at 120° C. The above results prove conclusively that the 

 essential substance contained in these bacilli is comparatively stable, 

 remaining undiminished in timothy grass and human tubercle bacilli which 

 had been dried and killed eight years previously, and also after they had been 

 autoclaved. 



Some further experiments were now made : 1 grm. of dried timothy grass 

 bacilli was taken and extracted with 20 c.c. of 0'8-per-cent. sodium chloride 

 and 4 c.c. of glycerine. The mixture was autoclaved for half an hour at 

 120° C. and passed through filter paper. The filtrate was then added to the 

 white and yolk of hens' eggs in the proportion of one part of filtrate to 

 three parts of egg. Another batch of medium was prepared by taking the 

 residue of the timothy-grass bacillus, washing it repeatedly with normal 

 saline, filtering it and drying the residue. This residue was made up into 

 medium, the tubercle bacillus of the original tubercle egg medium being 

 replaced by \ per cent, of the residue of the timothy-grass bacillus. Further 

 batches of medium were prepared by extracting the dried timothy-grass 

 bacillus with distilled water, the necessary quantities of sodium chloride and 

 glycerine being added after extraction and filtration. The residue was 

 treated as before. 



We found that Johne's bacillus grew on the medium containing the 

 glycerine saline extract, and on that containing the residue. It also grew 

 on the residue after extraction with distilled water, but it failed to grow 

 on the medium containing the distilled water extract. From these results 

 we judge that the essential substance is only very slightly, if at all, extracted 



