AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 519 



bacillus circulans Jordan 1890 



This organism was described originally by Jordan in 1890. The 

 present culture was obtained from normal human dejecta and cor- 

 responds closely with Jordan's description. 



Morphology. Rather long and thin bacilU with rounded or 

 square ends measuring about 0.5 by 2.5 to 4 microns in 24 hour 

 agar cultures. Occurs usually as single cells. Protoplasm homo- 

 geneous. On glucose agar the organisms are thicker and longer 

 measuring 0.75 by 5 to 8 microns. (Figure 75.) 



Motility, Active progressive and rotatory motihty in 24 hour 

 agar cultures. 



Staining properties. Gram-positive. 



Spore formation. Spores form early on plain agar often in 24 hours. 

 Abundant in 48 horns. Form more slowly on glucose agar. They 

 are cyhndrical, wider than the rods from which they spring and 

 terminal in position. The free spores may retain rims of proto- 

 plasm at one end or may be naked. They measure usually about 

 0.75 by 1.125 microns. 



Agar slant. Thin shghtly moist non-spreading growth, pale 



white in color. 



Agar colonies. Round regular non-spreading colonies, under low 

 power pale yellow, finely granular, with entire edges. Older colo- 

 nies become irregular and amoeboid showing under low power cen- 

 tral nuclei and thin peripheries. 



Agar stah. Faint growth along hne of inoculation spreading at 



point of puncture. 



Glucose agar. Faint thin non-spreading growth producing an 

 acid reaction beginning in 24 hours and quite marked at the end of 



5 to 6 days. 



Glucose agar colonies. Small fine colonies, under low power pale 

 yellow, granular with entire or serrated edges. Reaction acid. 



Gelatin siah. Faint growth along hne of inoculation. Little or 

 no surface growth. No hquefaction. 



Gelatin colonies. Small fine colonies with hazy outlines, under 

 low power dark opaque with fuzzy margins. Older colonies quite 

 amoeboid. No hquefaction. 



