Dr. Lucius Nicholls 



243 



In this stage it is not, always easy to isolate 

 the yeast cells by cultures, as they themselves 

 are being attacked and broken up by smaller 

 organisms. 



A colony of yeast growing upon a solid 

 medium is fairly easily . distinguished from a 

 colony of acetic-acicl-producmg or other 

 bacterium. 



Colonies, on a solid medium, of the wild 

 yeasts, including Saccharomyces theobromce, 



" FIG. 6. Three forms of acetic acid producing bacteria. 



consist of a central, heaped-up, granular portion 

 and, spreading away from this, a lighter, 

 thinner, radiating zone ; after a few days the 

 colonies lose the outer zone and assume a 

 white, opaque, granular appearance. These 

 are easily distinguished from most colonies 

 of other organisms, which usually possess a 

 shiny smooth-looking appearance. 



Sometimes it is found that the bean does not 

 undergo its proper and usual fermentation ; 



