A Sugar Bacterium. 



69 



as well developed as those in control plates in air at the same (low) 

 temperature. 



Streak cultures on black-sugar gelatine with yeast extract developed 

 very rapidly at and near 18° C. Instead of a spreading slimy mass 

 as on agar, these formed dense gelatinous, almost brittle, tear-like 

 drops and streaks standing a millimetre or more high, and curling up 

 oft' the surface of the gelatine in a most remarkable and characteristic 

 manner. 



On saccharonal-yeast-extract-gelatine similar raised streaks were 

 obtained, but less luxuriant than on brown sugar; possibly because 

 the temperature was lower, or only 10 per cent, saccharose was em- 

 ployed, or from lack of minerals. 



Beer-wort gelatine gave very slight indications of growth, soon 

 stopping, and never attaining anything like these dimensions, the mere 

 traces observed being probably due to saccharose in the wort. 



Certain mineral solutions — e.g., Kleb's solution — appeared to inhibit 

 the growth in the black sugar and gelatine. 



We have here gathered together the principal facts of its behaviour 

 on gelatine media, because they seem to bring out clearly that the 

 gelatine itself has little or no part to play in the nourishment of the 

 bacillus : mere traces of superficial liquefaction occur, and several 

 experiments show that it is of no slight importance what is added to 

 the gelatine, e.g., the surprising results of beer-wort gelatine. 



Agar. 



Agar (2 per cent.) made up with black sugar and yeast water rapidly 

 formed large slimy blister-like colonies in four days, both at 25° C. and 

 at 19° C. The contrast between these large, slimy, flat, and extended 

 colonies and the small, raised, dome-like, stiff ones, on gelatine was very 

 marked. 



Streak cultures on black sugar agar, with yeast extract, grew rapidly 

 as a dull, honey-like slime, spreading all over the surface in two days 

 at 16—18° and at 23—25° C, as well as at 36—37° C. 



Agar made up with peptone, &c, was of no use whatever, nor was 

 potato-agar. Even peptone-agar with black sugar proved unsuitable. 



Similarly unsuitable was agar made up with yeast extract and sac- 

 charose, which had been filtered through porcelain, though a pale 

 dotted streak formed at first at 25, 27, and 31° C. 



Agar (2 per cent.) made up with 10 per cent, saccharose and yeast 

 extract not filtered through porcelain, on the other hand, was an 

 excellent medium. In twenty-four hours at 30 — 31° C, a rapidly 

 growing slimy streak had formed, consisting of filaments up to 60 //. 

 long and more, breaking up into segments of all lengths down to 1*5 \x 

 by 1 /x. These showed no sheaths — they had turned slimy— stained 



