500 C. A. LAUBACH, J. L. RICE AND W. W. FORD 



Agar slant. Moderate growth along line of inoculation form- 

 ing a definite ridge. There is a tendency for the growth to 

 spread to either side and the opacity of the growth decreases 

 towards the periphery which is translucent. The growth is glis- 

 tening, raised, moist and has a pure white color which becomes 

 more apparent with age. 



Agar stab. Growth along the line of inoculation distinctly 

 granular. 



Agar colonies. The colonies are very characteristic. Some are 

 round and regular while others show a considerable tendency to 

 spread. They are moist, opaque, raised, glistening and white. 

 The majority show dense centers surrounded by thin areas which 

 are in turn surrounded by translucent shell-like peripheries. 



Glucose litmus agar slant. The growth is similar to that on 

 agar although somewhat variable as to amount. The distinct 

 white coloration is also evident. A definite and permanent 

 acidity is produced. 



Glucose litmus agar colonies. The colonies correspond closely 

 to those on agar but are less profuse. 



Gelatin stab. A fairly rapid progressive cone-like liquefaction 

 occurs. 



Gelatin colonies. The colonies rest in a cup-like excavation 

 caused by liquefaction. They are definitely circumscribed and 

 have an opaque center which is surrounded by a less dense gray- 

 ish area. This in turn is enclosed by a more dense grayish ring. 

 Outside this ring the opacity decreases towards the periphery. 



Broth. A fine fragile pellicle is formed with some turbidity. 

 The medium clears by sedimentation. 



Peptone. Similar scum but less marked turbidity. "* 



Potato. Cream-white moist profuse growth developing in 24 

 to 48 hours. 



Litmus milk. Within 24 hours a slight acid reaction occurs 

 and the milk often shows a distinct thickening at the bottom. 

 The coagulation is not definite however and peptonization begins 

 usually within 48 hours. As it advances a clear zone of amber- 

 colored fluid is found at the upper part of the milk tube. This 

 gradually increases until all the milk is peptonized. 



