304 J. S. LAWRENCE AND W. W. FORD 



agar in 24 hours and on glucose agar in 48 hours. They appear 

 in the center or shghtly towards one end of the rods and are 

 usually of the same diameter but may be slightly thicker. Some- 

 times two spores seem to arise in one rod but these may possibly 

 be in a rod just prior to division. In general each rod has a 

 single spore. The spores occasionally lie obliquely in the rods. 

 Frequently two spores are at opposite ends of rods lying in 

 juxtaposition and these may remain attached in chains and 

 present a characteristic appearance. The free spores retain 

 protoplasm at the ends for some time. When this is unequal 

 in amount the spore has somewhat the shape of a tennis racket 

 and handle. The free spores are oval to cylindrical and measure 

 0.75 to 1.125 by 1.5 to 2 microns. They are often flattened on 

 one side having an appearance described as kidney shaped or 

 reniform. The spores show great variations in size more so 

 than do those of the other members of this group. 



Slant agar. Thick, raised, soft, white or cream-colored growth 

 which shows a pink tinge by reflected light, with many small, 

 minute pellucid areas. As the cultures get older the growth 

 becomes pale yellow. 



Agar stab. Shght growth along line of inoculation, heaped 

 up and spreading slightly on surface. Later surface growth 

 becomes slightly pinkish. 



Agar colonies. Surface colonies round, thick, white or cream- 

 colored, highly refractive, turning pale yellow or yellowish- 

 brown in old cultures. Under low power slightly granular, 

 brownish yellow, with entire margins. Deep colonies puncti- 

 form. Under low power round or irregular with entire edges, 

 brown and granular. 



Litmus glucose agar slant. Thick, luxuriant growth along 

 line of inoculation, at first white and then pale yellow or cream- 

 colored. Medium is first acidified but later becomes alkaline 

 and changes from a dark blue to a smoky brown while the 

 growth becomes a dark gray or smoky brown. 



Litmus glucose agar colonies. Large, round, raised surface 

 colonies, cream colored to pale yellow, with heaped up central 

 nuclei. Under low power dark, slightly granular with entire 



