342 A GELATIN-HARDENING BACTERIUM. 



removed, the remainder remained firm when the temperature was 

 raised to 100°. In other cases the medium remained firm, dark 

 brown, and did not liquefy. 



Bacillus indurans, n.sp. 



Shape, etc. — The cells appear as rods with rounded ends. They 

 vary in size; when taken from saccharose-potato-agar and stained, 

 the smallest measure 0-5: 1-3 /x, the largest 0-6: 2-2 /x. When 

 taken from bouillon, they vary from 0*4 : 1 /x to 0-8 : 2 /m. Many 

 of the cells are vacuolated. The bacteria are active]}'- motile, the 

 flagella being numerous and peritrichous. They are negative to 

 the Gram stain. No spores were observed. 



Glucose-gelatin plate. — The colonies are flat, glistening and 

 translucent white with a lacerate edge. Microscopically they are 

 translucent and yellowish with central granules and club-shaped 

 structures scattered chiefly in the middle portions. The margin 

 is very finely granular. At a later date, when the colony has 

 sunk into the gelatin, a crumpling, especially at the margins, is 

 observed. 



Nutrient agar plate. — The colonies are raised, glistening, trans- 

 lucent white and rounded. When magnified the colonies appear 

 translucent and yellowish with granules scattered around the 

 centre. 



Glucose-gelatin stroke. — The growth is narrow, white and flat, 

 with lateral amoeboid offshoots. The medium may be very slowly 

 liquefied in the vicinity of the lower end of the stroke. A 

 reddish-mahogany colour appears in the upper layers and slowly 

 diffuses downwards, while the colour deepens. The white culture 

 takes up the colour and becomes a reddish-buff. The medium is 

 rendered insoluble. 



Glucose-gelatin stab. — The stab is filiform, the nail-head small, 

 white and flat. There is no apparent liquefaction, and the dark 

 colour slowly diffuses downwards. 



Nutrient gelatin stab. — A white flat surface-growth is imbedded 

 in the softened medium. The stab appears as a spiral thread 

 within a tube of soft gelatin. 



