E. M. DoiDGK 71 



grumose in the centre. Submerged colonies are minute, white and sub- 

 spherical. 



Seven days old colonies are up to 4 mm. diameter, apricot yellow, 

 they are beginning to sink in the centre owing to the softening of the 

 gelatine, the growth is slightly viscous. In nine days the gelatine 

 in the immediate vicinity of the colonies is liquefied, and in 14 days 

 liquefaction is complete. The colonies are still almost intact and 

 floating in the liquefied medium. 



Nutrient gelatine shake cultures develop very numerous minute 

 colonies, the majority of which are within 1 cm. of the surface of the 

 medium, which is slowly hquefied. 



Nutrient gelatine stab. The organism grows comparatively slowly 

 at 20° C, the growth along the needle track being barely visible at 

 the end of 24 hours. After seven days there is a fairly thick line of 

 growth all along the needle track, the surface colony is slightly sunken 

 in a small crater of liquefied gelatine. In 14 days liquefaction is napi- 

 form, the surface growth sinks to the bottom of the hc^uefied gelatine, 

 continually re-forming and sinking, thus forming a considerable amount 

 of sediment. The liquefied portion is clouded, and there are very 

 numerous minute opaque yellowish flocculi in suspension throughout 

 it. (Plate XI, a.) 



After 30 days the hquefaction is broadly saccate and extending to the 

 bottom of the tube, and in 6 — 7 weeks the gelatine is completely liquefied. 



Nutrient gelatine streak. In three days there is a shining yellowish 

 streak about 2 mm. wide and slightly raised in the centre. Liquefac- 

 tion begins on the fourth day; a small pocket of gelatine hquefying 

 near the bottom of the streak. The following day there is a groove 

 along the surface of the slope, from which the hquefied gelatine has 

 nm carrying the yellowish growth to the bottom of the tube. A fresh 

 streak forms in this groove, in its turn to be carried to the bottom of 

 the tube, and this process is repeated several times. The yellow growth 

 does not diffuse readily into the liquefied medium. 



Potato. On potato the bacillus grows well, a thin spreading yello\\ish 

 growth almost covers the sloping face of the cyhnder in 24 hours at 

 25° C. ; after three days the growth is primuline yellow to mustard 

 yellow, glistening, spreading, covering all the lower part of the cylinder 

 except where it is in contact with the tube and the greater part of the 

 upper drier portions. No growth is visible in the liquid in the bulb. 

 The potato is distinctly browned, the discoloration being most marked 

 in the tubes containing glycerinated potato. 



5—2 



