148 METHODS OF CULTURE AND ISOLATION 



straight side arm. It may be replaced as soon as the operation is 

 completed. It is not necessary to sterilize in the autoclave. The 

 Chamberland flask (Fig. 62) is an ordinary flask in which the col- 

 lar is drawn out and ground to receive tightly a straight cap which, 

 in turn, is drawn out. A piece of cotton may be inserted in this. 

 The Freudenreich flask is constructed a little after the same fashion 

 but differs in that the body of the flask is cylindrical instead of spheri- 

 cal. These may be sterilized in the autoclave. 



Some of the common media which may be used in the cultivation 

 of the yeasts are mentioned below. 1 



Pasteur's medium: 



Distilled water 1000 grams. 



Candied sugar 20 " 



Ammonium tartrate 0.1 



or, Ammonium carbonate 1.0 " 



Ash of yeasts 1.0 



This medium was used by Pasteur in the greater part of his 

 studies on alcoholic fermentation. 



Hansen's Medium No. 1. 



Peptone 1 gram 



Maltose 5 



Potassium phosphate 0.3 



Magnesium sulfate 0.2 



Distilled water 100.0 



Hansen's Medium No. 2 



Peptone - 1.0 gram 



Maltose .5.0 



Potassium phosphate 0.3 



Magnesium sulfate 0.5 



Distilled water 100.0 



Mayer's Culture Fluid: 



Sugar 15 grams. 



Potassium phosphate ' 5 



Magnesium sulfate 5 



Calcium phosphate 0.5 



Ammonium nitrate . 75 



Distilled water 1000.00 c.c. 



According to Mayer, this is a very useful medium for culturing 

 yeasts. 



1 Investigations by Wildier in 1901, by Williams in 1919 and Bachmann in 

 1919 indicate that some vitamine-like substance may be necessary for the growth 

 of yeasts. Apparently ordinary synthetic media alone are not entirely satis- 

 factory for the culture of yeasts. 



