Dec. 37,1915 Carbohydrate Transformations in Sweet Potatoes 
555 
further fact should be noted—viz, that the starch content of these pota¬ 
toes at the beginning of the first period is comparable in general with 
that of the potatoes at the beginning of the second period in the other 
experiments, while the final starch is much lower than in the other two 
groups. Similarly, the cane-sugar content at the beginning of the first 
period is comparable with that of the other groups at the beginning of 
the second period, but the final cane-sugar content is much higher than 
in either of those. 
Here it is even more evident than in the corresponding experiment at 
30° C. that the carbohydrate transformations were well under way at 
the time when the sweet potatoes were dug and that the data given in 
Table IV merely show the continuation of the processes which had 
already been started in the ground. 
If the experiments at 5 0 are now summed up, it is found that whether 
the potatoes had been dug while the vines were still active or some time 
after the vines had been destroyed there was a fairly uniform loss of starch 
during both periods. In the first two experiments only inconsiderable 
quantities of cane sugar were formed during the first period, but during 
the second period there was a marked accumulation of caije sugar. In 
the third experiment the accumulation of cane sugar was marked during 
both periods. In contrast to the cane sugar, there was a considerable 
accumulation of reducing sugar during the first period in the first two 
experiments and a slight loss during the second period. In the third ex¬ 
periment there was little or no accumulation during either period. 
The results of the experiments at 15.5 0 C. (Table V) do not present the 
same degree of uniformity as those at the other temperatures, but certain 
definite tendencies are evident. In the first experiment the loss of 
starch was large during the first period, but during the second the loss 
was not so great. Correspondingly, there was a considerable quantity 
of cane sugar formed during the first period and much less during the 
second. Very little change in the reducing sugar is evident during the 
first period, but during the second there is a distinct loss. It should be 
recalled here that the halves used in this experiment lost a large amount 
of water and that their behavior may have been influenced thereby, for 
from the work of Lundeg&rdh 1 it appears that the balance between oil 
and starch and sugar and starch in seedlings is shifted with changes in 
moisture content. The behavior of the roots in the second experiment 
is probably more nearly normal. Here the loss of starch is lower during 
the first period than at 30°, with no further loss during the second. 
The accumulation of cane sugar is not as great at first as at 30°, but is 
distinctly larger than during the second period. The increase in reducing 
sugar during the first period was comparable to that observed at 5 0 . 
During the second period there was a slight loss. 
1 Irtmdeg&rdh, Henrik. Einige Bedingungen der Bildung tmd Aufldsung der Starke. Em Beitrag zu 
Theorie des Kohlehydratstofifwechsels. In Jahrb. Wiss. Bot. t Bd. 53, Heft 3, p. 421-463. 1914. 
