342 BACTERIOLOGY. 



Fig. 65, a.) At times they may show indefinite mark- 

 ings or creases, somewhat suggestive of lobulations. 

 After forty-eight hours on gelatin they usually range 

 from one to three millimetres (some even larger) in 

 diameter, and will appear as sharply cut saucer-shaped 

 pits of liquefaction, in the most dependent portion of 

 which lies a dense, irregular mass, the colony proper. 

 Under low magnifying power they present at this stage 

 an appearance similar to that shown in Fig. 65, b, the 



Fig. 65. 



a i'- 



Colonies of the Mnkler-Prior bacillus on gelatin, x about 75 diameters. 



li. After twenty-two hours on gelatin at 20° to 22° C. 6. After forty-eight 



hours on gelatin at 20° to 22° 0. 



central dense mass representing the colony and the irreg- 

 ular ragged lines surrounding it being shreds that have 

 become torn away as it sank into the liquid caused 

 by its growth. The zone surrounding it, extending to 

 the periphery, is somewhat cloudy, and is simply lique- 

 fied gelatin. There is a marked tendency for the lique- 

 faction to spread laterally and for the colonies to run 

 together, so that, even on plates containing few colo- 

 nies, in sixty to seventy-two hours at from 20° to 

 22° C, the entire gelatin is usually converted into a 



