26 



HARRY WARREN ANDERSON 



TABLE s 



REACTION OF YEASTS ON SUGAR MEDIUMS 

 At 35 C. 



At 25 C. 



* The results are given in terms of the number of cubic centimeters of n/10 NaOH required to neutralize 100 c.c. 

 of the culture solution, assuming the original reaction to be exactly neutral. If there was a loss of acidity it is 

 expressed by the negative sign before the number. The check had an initial acidity of +0.95, but is recorded as in 

 order to compare with the other cultures. 



of acidity, as shown, for example, by the extreme alkalinity of dextrin 

 solutions. 



In general, when yeast water with an initial acidity of -\-l is used 

 with or without carbohydrates there is a decided decrease with some 

 species, while others show no marked change in the final reaction in 

 acidity. In spite of the wide variations in results due to these various 

 conditions, there are certain constant differences between species which 

 are useful in specific characterization. It will be seen from Tables 5 

 and 6 that Oidium albicans is a species which decreases the acidity of 

 the mediums in every case. It is also evident that the reactions of 

 Culture 2.5 are of the same general character as those of Oidium 

 albicans. On the other hand, Cultures 170 and 215.13 do not bring 

 about a decided decrease in acidity in any of the mediums. These 

 results are constant throughout the entire range of mediums and under 

 both conditions of temperature. 



The necessity of stating the period of time the culture has been 

 growing before the test of acidity is made is emphasized by the 

 results obtained after 5 days with Culture 2.5 and Oidium albicans. 



