CHARACTERS OF CULTURES 449 



sembling the colonies of the bacillus subtilis. Soon, however, 

 liquefaction occurs around the colonies, and spheres with turbid 

 contents result ; gas is developed around the colonies. 



In deep tubes of glucose agar at 37 C. growth is extremely 

 rapid. Along the line of puncture, growth appears as a some- 

 what broad white line with short lateral projections here and 



FIG. 132. Stab cultures in agar, five days' growth at 37 C. 

 Natural size. 



A. Tetanus bacillus. B. Bacillus of malignant oedema. C. Bacillus 

 of quarter-evil (Rauschbrand). 



there (Fig. 132, B). Gas may be formed, but this is most marked 

 in a shake culture, in which the medium becomes cracked in 

 various directions, and may be pushed upwards so high as to 

 displace the cotton-wool plug. The cultures possess a peculiar 

 heavy, though not putrid, odour. 



Spore formation occurs above 20 C., and is usually well seen 

 within forty-eight hours at 37 C. The spores have the usual 

 29 



