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A GELATIN-HARDENING BACTERIUM. 



(Bacillus indurans, n.spj 



By R. Greig Smith, D.Sc, Macleay Bacteriologist to the 



Society. 



Bacteria which soften and liquefy gelatin are very numerous, 

 but a microbe that hardens gelatin is, I think, a novelty. Such 

 a micro-organism was isolated during the bacteriological examina- 

 tion of the tissues of Schinus molle, the specimen of which was 

 exuding small quantities of a turquoise-coloured gum-resin. Two 

 bacteria were isolated; one of them, from the bacterioscopic 

 characters, appeared to be closely allied to, if not identical with, 

 Bad. acacice var. meiarabinum, and there its interest ends. The 

 other produced a slime,* but not in sufficient quantity to warran t 

 one in considering it to be of any importance on that account. 

 When it was grown upon ordinary glucose-gelatin in stroke 

 culture, the medium was slowly darkened in colour to a deep 

 reddish-brown or mahogany colour. There were no signs of 

 liquefaction, but on the contrary when the culture tube was put 

 into a beaker of water and the water boiled, the gelatin main- 

 tained its sloped position, which prolonged boiliDg did not alter. 

 The original medium would have liquefied soon after a temperature 

 of 25° had been reached. There was thus something secreted by 



* The slime was grown upon levulose-asparagin-tannin agar, and from it 

 a gum was prepared in the manner that has been frequently described. The 

 gum was coagulated by alcohol, basic and ammoniacal lead acetates, barium 

 hydrate and copper sulphate followed by potassium hydrate. Tannin gave 

 a slight opalescence. No reaction was obtained with copper sulphate, ferric 

 chloride, neutral lead acetate, or ferric chloride followed by ammonia. 



