A YEAST PRODUCING FOAMY CREAM 



TABLE 1 

 The relation of temperature to fermentation 



297 



*The percentage of gas refers to the amount formed in the closed arm of a Smith 

 fermentation tube. 



POWERS OF RESISTANCE 



Thermal death point 



Twenty-four hour lactose broth cultures were thoroughly 

 shaken and equal portions placed in sterile capillary pipettes of 

 uniform capacity and thickness of glass. Both ends were sealed 

 by heat and the sealed tubes were then placed in water baths of 

 constant temperatures for ten minutes. At the end of ten 

 minutes the tubes were removed from the water bath and cooled 

 by placing in cold water. The pipettes were opened aseptically 

 and tubes of litmus milk were inoculated with the contents and 

 incubated at 37° for four days. No growth was observed in 

 cultures made from these tubes after exposure to a temperature of 

 55 °C. or higher. The thermal death point therefore lies between 

 50° and 55°C. 



Resistance toward chemicals 



The yeast's resistance toward various chemicals was deter- 

 mined by using a twenty-four-hour lactose broth culture of the 

 organism. This was thoroughly mixed to break up all clumps 

 and masses. Three standardized platinum loops were used for 



