[Vol. 6 

 228 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



tions favorable for starch formation are not favorable for enzyme 

 activity and vice versa, since the enzyme activity was much 

 higher at night than during the day. These findings led Green 

 ( ? 97) to investigate the effect of light upon diastase. He found 

 the activity of the enzyme to be considerably decreased by 

 exposure to sunlight, the deleterious effect varying with the 

 intensity of the illumination. 



Brown and Morris also demonstrated that diastase, from 

 certain leaves at least, will hydrolyze solid starch, a point dis- 

 puted by Wortmann. They concluded, too, that their experi- 

 ments established almost beyond doubt, that, while protoplasm 

 may exert some influence upon the action of diastase upon starch 

 in the early stages of the action, the dissolution of starch is 

 mainly brought about by the enzyme diastase. 



In addition to their investigations of diastase in leaves, these 

 authors also worked upon the carbohydrate content of leaves. 

 They concluded that cane sugar, dextrose, levulose, and maltose 

 are present in leaves, but failed to find any pentoses. The 

 amounts of these sugars were found by them to increase in the 

 light and to decrease in the dark, with the exception of levulose, 

 which in many cases followed a reverse procedure. The increase 

 in levulose in the dark was attributed by them to the inversion 

 of cane sugar. 



Finally, these authors believed "starvation" of the cell to 

 induce the dissolution of starch through the formation of dia- 

 stase, and concluded that of the carbohydrates disappearing from 

 leaves in the dark, maltose and levulose contribute most to the 

 respiratory requirements of the cells. This idea of diastase 

 secretion being induced by starvation of the cell is concurred in 

 by Effront ('02, p. 139), who says: "The secretion [of amylase 

 by barley embryos] is always abundant when the germ is found 

 in poor nutritive condition, and it is checked as soon as an 

 assimilable substance appears/' 



The work of Meyer ('85) was briefly reviewed by Brown and 

 Morris in connection with their work on the carbohydrates of 

 the leaf. Meyer attempted to ascertain if the leaves of such 

 plants as Allium Cepa, which store no starch, contain any other 

 cupric-reducing carbohydrates comparable in amount with the 



