AEROBIC SPORE-BEARING NON-PATHOGENIC BACTERIA 301 



instances the organisms seem to be made up of a network of 

 fine strands in which the globular bodies hang suspended. Often 

 the chains are curled or curved upon themselves. Old cultures 

 show an abundance of swollen involution forms, which seem to 

 have a skein-like arrangement. (Figures 22, 23 and 24.) 



Motility. Active motility in young cultures. 



Staining properties. Gram-positive. 



Spore formation. Spores begin to form early, appearing first 

 as small retractile bodies in the centers or towards one end of the 

 organisms usually at the end of 24 to 48 hours. Gradually the 

 organisms swell and the spores at the same time increase in size 

 and at this stage a long chain of organisms each containing a 

 spore may often be seen. The protoplasm soon disintegrates 

 leaving a rim about the spore which is round or oval or slightly 

 rectangular. Such spores measure 0.75 to 1 by 1.125 microns. 

 Other spores are more definitely elongated and may measure 

 0.75 to 1 by 1 to 2 microns. The spores often remain attached 

 to each other in short or long chains. The spores vary more 

 in size than do others of this group and may show small forms 

 0.375 to 0.5 by 0.5 to 1 and large forms measuring 1.125 by 2 

 lying side by side. 



Slant agar. Filamentous rhizoid growth spreading from the 

 line of inoculation and extending into the agar. This growth is 

 at first glassy and glistening, but later grows dull and soft. Ap- 

 pearance on agar characteristic. 



Agar stab. Faint arborescent growth along line of inoculation 

 with a surface development in concentric zones. "^ 



Agar colonies. Surface colonies spread from dark dense 

 nuclei and show dense, rhizoid peripheries extending into the 

 agar on all sides. Under low power the periphery of the colony 

 is found to be composed of parallel strands of growth. Deep 

 colonies have almost the same appearance and always exhibit 

 the spreading peripheral myceleoid outgrowths. 



Litmus glucose agar. Thin membranous myceleoid growth 

 later becoming branched and reticulate. Growth at first 

 moist and white, later becoming pale yellow. Medium first 

 acidified and then turned deep blue. 



