1919] 



MCGINTY — DIASTASE ACTIVITY OF SOLANUM TUBEROSUM 227 



containing 5 cc. of chloroform per liter as preservative. The 

 digestion was carried on for 48 hours, after which the cupric- 

 reducing power of the solution was determined. Their experi- 

 ments showed diastase to be present in all leaves examined and 

 that it always possessed a decided activity, sufficient even in the 

 cases of the lowest diastase content to transform more starch 

 than the leaves ever contain at one time. These investigators 

 may therefore be considered to have added further evidence in 

 support of the view of Baranetzky, referred to above, that all 

 living cells contain diastase. Only a few facts remain which 

 render it somewhat doubtful. Duggar and Davis ( ? 14), in this 

 laboratory, were unable to demonstrate the presence of the 

 enzyme in Fucus, and Bradley and Kellersberger ('12) were 

 doubtful of its presence in such plants as onions, leeks, and 

 certain mushrooms. Failure to find diastase or invertase in 

 the flesh of ripe apples is also reported by Thatcher ( ? 15). 



The comparative tests of diastatic activity made by Brown 

 and Morris, referred to above, showed it to be especially high 

 in leguminous plants, while the members of the Liliaceae proved 

 to be poor in the enzyme, corresponding with the small amount 

 of starch they contain. To give an idea as to the relative 

 diastatic activity of the leaves of different species, as determined 

 by them, the following plants are selected from the large number 

 reported : 



Plant 



Pisum sativum 



Trifolium pratense 



Solatium tuberosum 



Lycopersicum esculent um . 



Allium Cepa 



Hydrocharis Morsus-ranae 



Relative diastatic 



activity 

 . . . 240.30 



89.66 



8.16 



6.57 



3.76 



.27 



Attention is directed to the position of the potato in this table, 

 which indicates a comparatively low diastase content. 



When the diastatic activity of a set of half-leaves gathered at 

 one time during the day was compared with that of the corre- 

 sponding half-leaves picked at another time during the same day, 

 it was found to vary considerably. They consider the figures 

 obtained in the last-mentioned case to indicate that the condi- 



