8o6 
Journal of Agricultural Research 
Vol. XXVH, No.io 
tively one-half and one-third of the increase of the nonreducing sugars. 
The highest ratio of the reducing sugars to nonreducing was that observed 
in the comparative experiment with Dwarf Yellow milo and Red Amber 
sorgo on July 17 and 18, 1919, when the maximum increase in the non¬ 
reducing sugars during the day was 1.09, and 0.79 gm. per square meter 
of leaf, respectively, for the milo and sorgo, while the maximum increase 
in the reducing sugars for an equal leaf area amounted to 0.62 gm. for 
the former and 0.57 gm. for the latter. 
By consulting figures 1 to 6 it will be seen that the graphs repre¬ 
senting the changes in the reducing sugars in the leaves of corn and 
the sorghums during the day are very irregular and that the time of 
the maximum increase in the amount of the reducing sugars very seldom 
if ever coincides with the time of the maximum amount of the nonre¬ 
ducing sugars. No significant differences were observed between corn 
and the sorghums in regard to the relationship between the reducing 
and the nonreducing sugars in their leaves. The observations made in 
these experiments in regard to the behavior of the nonreducing and the 
reducing sugars in the leaves of com and the sorghums during the day 
and night are in accord with those of Brown and Morris (1), Parkin 
(n) and Davis (3, 4, 5) who worked, respectively, with the leaves of the 
nasturtium, snowdrop, and the mangold and potato. Since the non¬ 
reducing sugars increased so markedly in the leaves during the day 
and then decreased during the night, while the reducing sugars remained 
almost constant, these investigators concluded that the nonreducing 
sugars were the first sugars formed in the leaves in photosynthesis. It 
would seem, however, that it can not be determined definitely from 
chemical analyses whether the marked increase in the amount of the non- 
reducing sugars in the leaves during the day is due to the fact that 
they are the primary sugars of photosynthesis or to the fact that they 
are formed from the more simple sugars and accumulate in the leaves 
during the day as temporary storage products. 
SUMMARY 
In order to determine the changes of the carbohydrates in the leaves 
of corn and the sorghums during the day, analyses were made of material 
collected at two-hour intervals from the leaves of Pride of Saline corn, 
Dwarf Yellow milo, and Red Amber sorgo grown under identical or 
similar field conditions during the summers of 1916, 1917, and 1919. 
Ten sets of plants were under observation and the more important 
data obtained were as follows: 
(1) The amount of dry matter in a given area of leaf of the sorghums 
studied was always greater than a like area of leaf of the com. The 
dry matter in the leaves of both plants began to increase at daylight, 
reached a maximum at periods varying from 2 to 6 p. m., and then 
gradually diminished until daylight the following morning. In the 
comparative experiments with corn and milo the maximum increase in 
dry matter per square meter of leaf during the day was approximately 
twice as great in the leaves of milo as in the leaves of com. 
(2) The amount of water in a unit of leaf area was always greater in 
the leaves of corn than in the leaves of the sorghums. The water con¬ 
tent of the leaves of both plants began to decrease anywhere from mid¬ 
night to 5 a. m., reached a minimum from 12 m. until 3 p. m., and then 
began to increase until a maximum was reached the following morning. 
