1910.] 



Galactose by Yeast and Yeast-juice. 



649 



The phosphate added was equivalent to 16'7 cc. of CO2 at N.T.P. in the 

 ratio XaaHPOi : CO2. 



The phenomena observed with galactose are therefore precisely the same 

 as those exhibited by glucose. 



VI. Formation of an Organic Phosphate. 



25 cc. of juice + 2 grammes galactose were incubated and phosphate 

 added in small quantities until no further acceleration could be produced. 



When the rate had fallea to its original value, the free phosphate in the 

 boiled and iiltered liquid was estimated. 



Free phosphate found was equivalent to 01400 gramme Mg2P207. 



The phosphate added corresponded to 0-3953 „ „ 



Hence phosphate equivalent to 0"2553 gramme Mg2P207 has been con- 

 verted into a form not precipitable by magnesium citrate mixture. The 

 constitution and properties of this compound are under investigation. 



VII. Fermentation of Galactose hy Yeast-juice in Presence of Arsenate. 



As with glucose the addition of small quantities of sodium arsenate to a 

 fermenting mixture of galactose and yeast-juice produces an acceleration, bat 

 hitherto it has only been found possible to double the rate in this way. 



Conclusions. 



1. The statement by various workers that some yeasts can be trained to 

 ferment galactose by cultivation in a medium containing that sugar, has been 

 confirmed. 



2. Such a trained yeast yields a juice capable of fermenting galactose. 



3. A fermenting mixture of yeast-juice and galactose reacts with phosphate 

 in a similar manner to yeast-juice and glucose. The rate is accelerated, an 

 extra amount of CO2, equivalent to the phosphate added, is evolved and the 

 rate then again becomes normal. The phosphate is converted into an organic 

 compound not precipitable by magnesium citrate mixture. 



4. The fermentation of galactose by yeast-juice is also accelerated by the 

 addition of small ciuantities of sodium arsenate. 



