ni CHARACTER OF BACILLUS rj 



are crowded with gas-bubbles, the upper layers of the 

 gelatine remaining free from them. Gradually, how- 

 ever, the gas-bubbles disappear, i.e. escape on to 

 the surface, and by the end of eight or ten days 

 all but the deeper situated bubbles have disappeared. 

 The escape of the gas -bubbles between the gela- 

 tine and the glass wall of the test-tube can be 

 easily ascertained. 



On nutrient Agar at 36-37° C. the microbes grow 

 with great rapidity ; in two or three days the sur- 

 face of the Agar becomes covered with a greyish- 

 white thin film. 



In alkaline beef broth (with i per cent peptone), 

 incubated at 36-37° C, there is, after 24 hours' growth, 

 strong uniform turbidity, which reaches its maxi- 

 mum in about 3 days ; at the same time there is 

 a copious greyish floccular or granular precipitate. 

 After about 5-7 days there is noticed, just at the 

 point where the surface of the fluid is in contact 

 with the glass of the test-tube, a ring of whitish 

 growth ; but there is at no time a distinct pellicle 

 formed on the surface. On potato, previously steril- 

 ised in the steam steriliser, the microbe grows well 

 at 36-37° C, forming in a few days a light yellow- 

 brown, limited film, which looks like paint, and 

 does not spread much over the surface of the 

 potato. 



