32 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



Preparation of a Pure Culture of Yeast. — ^It is possible in 

 the case of yeast actually to separate a single cell from the 

 rest of the culture and inoculate suitable media from this 

 single cell. This method, which is of great technical importance 

 in the control of the various fermentations due to yeast, was 

 introduced by Hansen. The following description is based 

 upon that given in Brown's ' Laboratory Studies,' p. 160. 



Fig. S.—Eeeitdenbeich Elask, Sqtjabed Covee Glass, and Moist 

 Chamber, eob Yeast Ctjltuee. 



The following are the requisites for the method :— 



A sterilised glass plate and beU jar, or other cover. 

 Sterilised glass rods. 

 Sterilised Botcher chamber. 



Sterilised cover glass divided into numbered squares. 

 Freudenreich flasks of sterHised wort gelatine and of 

 sterilised water. 



The Freudenreich flask, the moist chamber and the squared 

 coyer glass are shown in Fig. 8. Mix a drop of fresh yeast 

 mth sterflised water in a Freudenreich flask, shake well and 

 dilute still further by transferring a drop of the mixture to a 



