240 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



(Vol. C 



however, it must be remembered, kept the juice under different 



condit 



here, it would seem 



desirable to repeat the work of the latter authors, em 

 conditions under which their results were obtained. 



Carbohydrate 



>f 



carbohydrate 



tubers used in this work is given in table 



figures 



gars, sucrose, and 



determined as glucose, present in 50 gms. (green weight) of 



the freshly dug tubers at each stage of growth. No analyses 

 were made of tubers 1 cm. in diameter, due to the fact, as stated 

 before, that while enough of the potatoes of this size were availa- 

 ble for the diastase activity determinations, there was not suffi- 

 cient quantity to make also the sugar and starch determinations. 

 The results given in table iv show a gradual decrease, with 

 advance in development, in the amount of reducing sugar 

 present, which is accompanied up to a certain point by a corre- 

 sponding increase in the amount of sucrose. The latter falls off 





rapidly, however, as the tuber approaches maturity. This is in 

 agreement with the limited data of Hungerbuhler ('86), who 

 also found a decrease in the reducing sugars and an increase in 

 invert sugar, with advance in maturity. The results of Schulze 

 and Seliwanoff ('88), who found sucrose to be abundant in the 

 immature tubers, are also confirmed. 



TABLE IV 



CARBOHYDRATE 



GROWTH 





Stage of growth 

 (diameter in cms.) 



No. gms. carbohydrate, determined as glucose, in 



50 gms. green tubers 





Reducing sugar 



Sucrose 



Starch 



2 

 3 

 4 

 5 



6 



.3854 

 .3307 

 .2388 

 .0774 

 .0127 



Seed potato 

 Seed potato 



.1360 

 .1857 



.4217 

 .4395 

 .6358 

 .6194 

 .0924 



.0722 

 .0675 



6.963 

 6.039 

 6.236 

 7.494 

 7.632 



7.065 

 8.650 



I 



