AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 517 



initial acidity which is rapidly replaced by a permanent alka- 

 linity. The growth wrinkles slightly. 



Glucose litmus agar colonies. Grayish, moist, opaque glisten- 

 ing and slightly wrinkled colonies. The reaction is the same as 

 that on the glucose litmus agar slant. 



Gelatin stab. A definite granular growth along the line of in- 

 oculation followed by complete liquefaction. The liquefaction 

 is funnel-like. 



Gelatin colonies. Definitely circumscribed grayish, moist, 

 glistening colonies with opaque centers and thin lace-like pe- 

 ripheries. The colonies rest in excavations caused by Hquefaction. 

 On examination with the low power, they appear to be composed 

 of large flocculi. 



Broth. A very turbid growth which clears by sedimentation. 

 No pellicle is formed. 



Peptone. Growth similar to that in broth. 



Potato. Fairly abundant, moist, heaped up, glistening, vis- 

 cous and grayish growth. 



Litmus milk. No change is noticed within 96 hours, after 

 which period a slight reduction becomes evident. The reduction 

 is completed within about 7 days and then the milk is slowly 

 peptonized. Peptonization is generally completed within 14 

 days. The remaining liquid is at first grayish in color but after 

 a variable period becomes amber-colored. 



Blood-serum. A fairly abundant, thin, smooth, slowly spread- 

 ing, slightly glistening, brownish growth occurs. No liquefac- 

 tion of the medium. 



Fermentation tubes. Glucose: a turbid growth occurs in the 

 bowl and neck but does not extend up the closed arm. No scum 

 is formed and a very slight initial acidity is produced which 

 gives way to a slight alkalinity. 



Saccharose : the growth corresponds closely to that in glucose. 

 There is a slight alkalinity. 



Lactose : the growth is similar with the production of a slight 

 alkalinity. 



Thermal death point. The spores survive 10 pounds in the auto- 



