AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 311 



Spore formation. In the Krai culture the spores were at first 

 formed very slowly appearing only after the lapse of 15 to 16 

 days. Subsequently after repeated transfers, spore formation 

 became more active and spores were often formed in 24 hours. 

 They appeared in the centers or towards one end of the rods, 

 were no thicker than the rods from which they sprung, and were 

 cylindrical or almost rectangular in shape. They retained rather 

 thick walls of protoplasm for some time and measured 0.5625 by 

 1.125 to 1.25 microns. In our own isolation the spores were 

 formed in 48 to 72 hours in the same way as in the Krai culture but 

 were a trifle smaller measuring 1.375 to 0.5 by 0.75 to 1 micron. 



Agar slant. Thin, translucent, sHghtly yellowish gelatinous 

 growth, gradually becoming denser and developing occasionally 

 a dry slightly wrinkled surface. Single accessory colonies not 

 uncommon at the edges of the main growth. 



Agar stab. Slight uniform growth along line of puncture with 

 a thick circular surface growth. 



Agar colonies. Surface colonies thin, translucent, amoeboid 

 developing from pin-point centers. Under low power granular. 

 Deep colonies round or oval, regular, granular, with clean or 

 rarely irregularly fuzzy edges. 



Litmus glucose agar. Thick, abundant yellowish-white, heaped 

 up growth with serrated margins. Medium faintly acidified 

 in old cultures. 



Litinus glucose agar colonies. Superficial colonies thin, smooth, 

 white and soft. Under low power granular, edges irregular 

 but entire. Deep colonies punctiform. Under low power 

 irregular with irregular rarely fuzzy margins. A trace of acid 

 usually produced. 



Gelatin stab. Faint growth along fine of inoculation with 

 eup-shaped surface liquefaction. 



Gelatin colonies. Round, thick, whitish colonies with con- 

 centric rings and sharply defined edges. Medium liquefied. 



Broth Faint turbidity, shght sediment, no scum but rarely a 

 faint ring growth along side of tube. 



Litmus milk. Gradual clearing with production of straw- 

 colored fluid in the Krai culture. In our own isolation a gradual 



