CULTIVATION OF THE BACILLUS 87 



quantity to add. To obtain the best results, the 

 dried bacilH should be ground up with the glycer- 

 ine which has been mixed with an equal quantity 

 of o*8 per cent, saline, and the remainder of the 

 saline added later. The emulsion so obtained 

 should then be steamed for fifteen minutes, and, 

 when cool, added to the Ggg. The probable ex- 

 planation for this is that the glycerine acts as a 

 solvent for the essential substance, and some ex- 

 periments to be described later tend to confirm 

 this suggestion." 



On p. 529 we discussed these later experiments thus : 



** Some further experiments were now made : 

 I gramme of dried timothy-grass bacilli was 

 taken and extracted with 20 c.c. of o'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 the 

 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. . . . We 

 found that Johne's bacillus grew well on the 

 medium containing the glycerine saline extract 

 and on that containing the residue." 



On p. 525 we also state : 



** In another series of experiments the egg was 

 replaced by various other substances, such as 



