AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 293 



are thicker and much longer measuring often nearly 0.75 microns 

 in thickness and 5 microns in length. (Figures 6 and 7.) 



Motility. Active progressive and rotatory motiUty in young 

 cultures. 



Staining properties. Gram-positive. 



Spore formation. Spores are formed early appearing in 24 

 hours on plain and glucose agar. They arise in the center or 

 towards one end of the rods but do not ordinarily bulge the rods 

 appreciably. When free they are elongated and flattened and 

 retain tags of protoplasm at each end. At times the protoplasm 

 at one end is greater in amount then at the other. Such spores 

 measure about 0.5 by 1.125 microns. As they lose their protoplasm 

 they become cylindrical measuring about 0.5 by 1 micron. In 

 general the spores are about the same width a.s the vegetative 

 rods or only very shghtly wider. 



Agar slant. Moist profuse thick growth on agar, easily 

 hfted or brushed from the surface of the medium with the plati- 

 num wire. Growth is usually white or cream white, spreads 

 but little from the hne of inoculation and is whitest at the edge 

 where it is heaped up. When water of condensation washes 

 over the agar many small, round colonies develop apart from 

 the main growth. In some strains the agar growth is dry and 

 fine wrinkles develop but the growth can always be lifted from 

 the agar w'th a platinum loop. 



Agar stab. Little growth along line of inoculation but rather 

 dry wi'inkled rooty growth spreads over the surface of the agar. 



Agar colonies. Surface colonies round, waxy, highly refrac- 

 tive or spreading and amoeboid with greatest refraction at the 

 edge of the advancing growth, where colonies are thickest. 

 Under low power of the microscope edges entire. Deep colonies 

 punctiform, round or elliptical. Under low power they are 

 irregular, brown, slightly granular with entire or fuzzy edges. 



Litmus glucose agar slant. Characteristic appearance. Luxu- 

 riant diy hTown and abundantly wrinkled growth develops 

 within 24 to 48 hours. The medium is acidified. After a few 

 days the growth usually becomes moist and the wrinkles are 

 obUterated while the medium becomes alkahne and turns deep 

 blue. 



