218 BACTERIOLOGY. 



After twenty-four hours in the incubator the plates 

 will be seen to be studded here and there with yellow or 

 orange-colored colonies, which are usually round, moist, 

 and glistening in their naked-eye appearances. Under 

 the low-power hand-lens they are frequently irregularly 

 star-shaped or lobnlated in outline and appear very dense 

 in structure. Under the low objective they appear, when 

 on the surface, as coarsely granular, irregularly round 

 patches, with more or less ragged borders and a dark 

 irregular central mass, which has somewhat the appear- 

 ance of masses of coarser clumps of the same material 

 as that composing the rest of the colony. When deep 

 down in the culture medium they present but little that 

 is typical. Microscopically, these colonies are composed 

 of small round cells, irregularly grouped together. They 

 are in every way of the same appearance as those seen 

 upon the cover- slip preparations. 



Prepare from one of these colonies a pure stab culture 

 in gelatin. After thirty-six to forty-eight hours lique- 

 faction of the gelatin along the track of the needle, and 

 most conspicuous at its upper end, will be observed. As 

 growth continues the liquefaction becomes more or less 

 of a stocking-shape, and gradually widens out at its 

 upper end into an irregular funnel. This will continue 

 until the whole of the gelatin in the tube eventually 

 becomes fluid. There can always be noticed at the 

 bottom of the liquefying portion an orange-colored or 

 yellow mass composed of a number of the organisms 

 which have sunk to the bottom of the fluid. 



On potato the growth is quite luxuriant, appearing as 

 a brilliant orange-colored layer, somewhat lobulated and 

 a little less moist then when growing upon agar. It 



