CARBOHYDRATE METABOLISM AND GROWTH IN EDIBLE CANNA 23 
whereas, the total sugars of the stems were far lower than those of the 
rootstocks, owing primarily to their low hexose content. The very 
low percentages both of dry matter and of starch in the rootstock were 
in contrast to the hills previously mentioned. The solids other than 
starch had practically the same values as hills 1 and 2. The occur- 
rence of starch in the stems has been previously noted in a similar 
bill. (Table 6, hill 3.) 
Within the stem the hexoses seem to be an index of the amount 
of material being furnished to the rootstock for starch formation. 
The sucrose has a more constant value and shows less correlation 
with the growth of the hill. In the rootstock, however, the sucrose 
follows the variations of the hexoses of the stem rather closely and 
thus furnishes a possible index of the rate of storage of starch. The 
hexoses remain low and fairly constant in the mature rootstock, 
but increase in concentration in the youngest growth, and may be 
considered as an index of the rate of cell growth in the young 
rootstock. 
It is a significant fact that the curve for the sucrose content of the 
rootstocks follows very closely that of the hexoses of the correspond- 
ing stems. Davis, Daish, and Sawyer (6) suggest that, in case of the 
sugar beet, a larger quantity of hexoses is found when the hexoses 
enter the root in excess of its "saccharifying power.' The accumu- 
lation of sucrose in the edible canna rootstock might be due to its 
production in excess of its "amylogenic power," in which case the 
increase in the sucrose of the older groups might be attributed to a 
decrease in this power rather than to any increase in the rate of 
formation of starch. That starch formation was still taking place 
was shown by the increase in the percentage of starch over that of 
preceding groups. Evidently change from hexoses to sucrose was 
rapid, since in no instance did the hexose content of a Group 2 root- 
stock show any increase, regardless of the percentage of hexoses in 
the stem. The high concentration of the hexoses in the stems of 
Group 2 would seem to indicate that this is the stage in which the 
stem sends the largest quantity of sugars to the rootstock. Sample 
No. 3, old Group 2, had the highest sugar content notwithstanding 
the fact that it had only few green leaves at the top. 
In Group 3a, comprising immature stems, the sugars decreased 
sharply. This indicates that much of the synthesized plant foods 
are carried to the growing portions of the stem instead of to the 
rootstock, and that the stem does not function at its maximum in 
supplying sugars to the rootstock until all new growth ceases. 
The hexoses within the rootstock of Groups 1, 2, and 3a were uni- 
formly low. The slight effect on the hexoses of the large variations 
in the stems as well as in the sucrose of the rootstocks in Groups 2 
and 3a is surprising. Using the reducing sugars as a criterion, it is 
seen that, in Groups 2 and 3a, the sugars were carried down the 
stem at the maximum rate although active cell growth of the root- 
stock had largely ceased. This would seem to indicate that the process 
of starch formation within the rootstock continues long after active 
cell growth ceases. Reference to the starch content of the different 
groups tends to bear out this observation. In sample No. 6 cell 
growth was still taking place since the stem had not begun to develop 
and the apical growth was meristematic. The hexoses were compar- 
atively high, whereas the starch content was very low. The stem 
