G. MCGUIRE AND K. G. FALK 227 



starch. The marked action observed in the more acid solutions was 

 due to the sucrase. 



SUMMARY. 



The saccharogenic enzymes present in potato juice were studied. 

 The actions were followed upon the substances present in the juice 

 and upon added sucrose, maltose, and soluble starch. 



Sucrase and amylase were found to be present in the juice. No 

 indication of a maltase was obtained. 



The sucrase showed optimum conditions for action at pH 4 to 5, 

 the amylase at pH 6 to 7, both upon the starch present in the juice 

 and upon added soluble starch. 



The action of a yeast sucrase preparation upon the juice showed 

 the presence of sucrose (or rafhnose) in a concentration of the order 

 of magnitude of 1 per cent. 



