K. G. FALK AND G. McGUIRE 609 



starch into sugars. It is most rapid while the fruits are turning from 

 green to yellow. During this period the respiration rate increases 

 manyfold, becoming greatest at the time when the rate of starch 

 hydrolysis is most rapid."- Bailey i*' showed that the banana ripened 

 in the presence of oxygen, but not in gases such as hydrogen, carbon 

 dioxide, etc. It is therefore possible that the ripening process, or 

 the breaking down of the starch, is not merely an amyloclastic action 

 as this is commonly understood, but involves a simultaneous or pre- 

 liminary oxidation reaction. 



SUMMARY. 



A number of different methods of treatment of unripe and ripe 

 bananas for the purpose of obtaining and studying sucrolytic and 

 amylolytic enzymes are described. 



No conclusive evidence of the presence of an amlyase could be 

 obtained in any of the preparations. 



The sucrase of unripe and ripe bananas was studied more exten- 

 sively. With ripe bananas, both soluble and insoluble sucrase prep- 

 arations were obtained. Conditions for converting the soluble into 

 an insoluble form were found. The actions of the sucrase prepara- 

 tions as far as the hydrogen ion concentration for maximum action 

 and the time-action relation are concerned are similar to the behavior 

 of the yeast and the potato sucrase. 



1^ BaUey, E. M., /. Biol. Chem., 1905-06, i, 355. 



