AEROBIC SPOEE-BEARING NON-PATHOGENIC BACTERIA 305 



edges. Deep colonies punctiform. Under low power dark, 

 irregular, bizarre, with entire edges. Medium is acidified and 

 then made alkaline. 



Gelatin stab. Funnel-shaped hquefaction. No scum. 



Gelatin colonies. Round colonies with concentric zones of 

 growth. Under low power cloudy central nuclei with filamen- 

 tous peripheries. 



Broth. Turbidity but no scum. 



Peptone. Turbidity but no scum. 



Potato. Thick, white, mealy growth later becoming pale or 

 cream yellow. 



Litmus milk. No change within 24 hours then a gradual 

 peptonization with the production of a port-wine colored fluid. 

 No acidification. No coagulation. 



Blood serum. Thick, white, moist, heavy growth cream white 

 to yellow in color. No liquefaction. 



Fermentation tubes. Glucose. Turbidity in open bulb. No 

 scum. No growth in closed arm. Acid production feeble. 



Saccharose. Turbidity in open bulb. No scum. No growth 

 in closed arm. Acid production feeble. 



Lactose. Shght turbidity in open bulb. No scum. No 

 growth in closed arm. Reaction alkaline. 



Thermal death point. Spores withstood 1 hour steaming in the 

 Arnold sterilizer and 18 pounds pressure in the autoclave. 

 Killed by 19 pounds pressure. 



V 



Bacillus petasites Gottheil 1901 



This organism was described originally by Gottheil (1901) in 

 1901. Its chief point of differentiation from Bacillus megatherium 

 is that it produces a distinct yellow pigment on artificial media, 

 particularly on plain agar and on potato. It is extremely com- 

 mon, having been found in dust, soil, water, milk, and various 

 milk products. The present description applies to a culture 

 from the Krai collection and to over a hundred of our own 

 isolations. 



Morphology. The organisms do not differ appreciably in 

 morphology from Bacillus megatherium. They are homogeneous 



