108 



PHYSIOLOGY OF ALIMENTATION. 



experiment of allowing yeast maltase to act at 30 C. upon a 

 40-percent solution of dextrose for a number of months, and 

 found that this same ferment, which is able to bring about the 

 analysis of the maltose, is also able to bring about its syn- 

 thesis from the products of the analysis. HILL determined 

 the appearance of maltose and its gradual increase in the dex- 

 trose solution by means of the polariscope and copper reduc- 

 tion tests. Since maltose is able to rotate the plane of polar- 

 ized light more to the right than dextrose, and since dextrose 

 has a greater reducing power than maltose, it is possible 

 through analysis to determine whether in a mixture of the 

 two sugars one is increasing at the expense of the other. 

 Column A in the following table shows how, under the influ- 

 ence of yeast maltase, the rotating power of a pure dextrose 

 solution gradually increases, while column B shows how its 

 reducing power gradually decreases. Columns C and D indi- 

 cate the percent of maltose contained in the originally pure 

 dextrose solution, as calculated from the figures obtained in 

 the first two columns. The values obtained by the two 

 methods of analysis agree very well. 



Maltase seems, therefore, to have a reversible action and 

 is able not only to split maltose into dextrose, but also to syn- 

 thesize the disaccharide from the monosaccharide. The 

 chemical reaction expressing this may be written as follows: 



Maltose 



Water 



Dextrose 



Dextrose 



