O on l Vo1 " & 



460 ANNALS OF THE MISSOURI UOTANICAL GARDEN 



the total sugars to decrease gradually as the plants matured, 

 while the starch apparently increased until the vines were killed 

 by frost, at which time it was at its maximum. Killing of the 

 vines by frost was followed by a breaking down of starch with 

 a tendency toward the formation of sucrose. 



The 



his 



small immature tubers harvested on August 28, and for suc- 

 cessive stages until the potatoes we:e mature: 



Date Starch Glucose Sucrose 



Aug. 28 17.88 61 4.18 



Sept. 7 14.91 1.58 1.82 



Sept. 18 17.61 1.88 1.91 



Sept. 29 19.92 2.30 1.43 



Nov. 18 17.82 1.53 2.35 



(A freeze occurred on Nov. 6 which killed the vines.) 



It has been generally assumed that transformations brought 

 about through the agency of enzymes are reversible; that is, 

 diastase which hydrolyzes starch to maltose also acts as the 

 synthesizing agent in the production of starch. The hydrolytic 

 processes have, of course, received most attention, but have not 

 been exclusively investigated. The synthetic aspect of the prob- 

 lem was attacked by Bradley and Kellersberger ('12). In view 

 of the results obtained, they were unwilling to make any general 

 deductions as to the relation between the diastatic activity of a 

 tissue and its starch-storing function, though their determina- 

 tions seemed to give considerable support to the view that the 

 enzyme is the synthesizing agent. One reason for their hesitancy 

 in formulating a conclusion was their inability to explain the 

 fact that fresh mushroom tissues, rich in a glycogen-like carbo- 

 hydrate, when allowed to act upon a soluble starch solution for 

 five days, showed no evidence of diastase activity, while the 

 same tissues ground up with alcohol, washed with ether, and 

 dried, developed considerable activity. They thought this 

 might be explained by the fact that the treatment activated a 

 proenzyme, but if such were the case, they could not understand 



mushroom 



be rapid 



enzyme 



