AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 507 



parent or shadow forms abundant on plain and on glucose agar. 

 These measure usually 0.75 to 1.125 by 2.5 to 4 microns. In old 

 cultures an abundance of viscous substance appears staining 

 slightly with gentian violet. (Figures 65, 66 and 67.) 



Motility. Active motility in young cultures. 



Staining properties. Gram-positive. 



Spore formation. When first isolated, spores were formed 

 within 48 hours. After long cultivation on artificial media, the 

 spore fomiation has become considerably delayed. Spores are 

 now formed only in ten to fourteen days. They are central or 

 slightly ex-centric and resemble the spores of Bacillus subtilis. 

 They measure usually 0.5 to 0.625 by 1 to 1.125 microns and are 

 thus oval to cylindrical. They do not bulge the organisms vfhen 

 formed. 



Agar slant. Within 48 hours there is a fair growth which is 

 moist, glistening, non-spreading, glairy and transparent. Its 

 characteristic quality is its viscosity. Later the growth becomes 

 dull and grayish in its appearance and loses its viscosity. A slight 

 wrinkling appears along the outer edge of the growth and forms 

 a narrow border surrounding the entire line of growth. After a 

 few days the medium acquires a brownish color. 



Agar stab. A faint granular growth along the line of 

 inoculation. 



Agar colonies. Colonies round, definitely circumscribed, with 

 but little tendency to spread, raised, dull and viscous. There is 

 a scum-like covering which encloses gelatinous material about 

 each colony which is very characteristic. 



Glucose litmus agar slant. The growth is bluish-gray, viscous, 

 wrinkled and dull. A sHght reduction of the Htmus occurs with 

 a definite acidity. There is a later return to alkalinity usually 

 within ten days. 



Litmus glucose agar colonies. The colonies are similar to those 

 on plain agar but are more profuse and have a definite bluish- 

 gray color. 



Gelatin stab. Rapid progressive surface liquefaction. Com- 

 plete liquefaction occurs within 96 hours with the formation of a 

 definite flocculent sediment. 



