AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 511 



Bacillus laterosporus nov. sp. 



This organism was obtained but once, from water. It is ap- 

 parently a new species. 



Morphology. The typical vegetative rods are found only m 

 very young cultures 6 to 8 hours old. They are homogeneous or 

 slightly granular with round ends, measuring 0.375 to 0.5 by 

 1.125 to 4 microns on plain agar. On glucose agar they are 

 slightly thicker and about the same length measuring 0.5 to 0.75 

 by 1.125 to 4 microns. The rods rapidly lose their characteristic 

 appearance and assume a fusiform or spindle shape with a swol- 

 len middle and pointed ends. Such forms take the stain much 

 less intensely. (Figures 71 and 72.) 



Motility. Active motility in young cultures. 

 Staining properties. Gram-positive. 



Spore formation. As the organisms swell and assume the fusi- 

 form shape the spores appear at one side as slightly staining 

 globules. The protoplasm soon disintegrates but more on one 

 side of the spore than on the other so that the free spores which 

 are almost egg-shaped retain a rim of protoplasm on one side and 

 present a characteristic appearance. Such spores measure 0.75 

 to 0.875 by 1.5 microns. As the spores mature they lose their 

 rims of protoplasm, become more oval and measure 0.75 to 1 by 

 1 to 1.125 microns. The spores begin to appear in about 48 hours 

 and are abundant in 72 hours. Rarely small tags of protoplasm 

 remain attached at the ends of the spores. 



Agar slant. The growth is very characteristic. It is profuse, 

 rapidly spreading, smooth, moist, and has a silvery metallic-hke 

 lustre. Within 72 hours the growth becomes sUghtly wrinkled. 

 With age the growth loses its metalhc lustre and becomes dull 

 and scrapes off in scales. 



Agar stab. A slight grayish granular growth along the line of 



stab. 



Agar colonies. The colonies are flat, transparent, irregular, 

 moist, and have the same pecuhar metallic lustre. 



Glucose litmus agar slant. Growth shght, granular, moist and 

 gray. Shght reduction of the htmus within 24 hours and a per- 

 manent acidity within 96 hours. 



