Mar. 8,1924 Carbohydrate Variations in Corn and Sorghum Leaves 807 
In the case of com the amount of water seemed to become a limiting 
factor in the production of dry matter when it reached a minimum of 
about 112 gm. per square meter of leaf. The water content of the sor¬ 
ghum leaves reached a minimum of 98 gm. per square meter of leaf, but 
this minimum apparently in no way retarded the production of dry 
matter. > 
(3) The total sugars in the leaves of the plants under observation 
began to increase between 4 and 6 a. m., reached a maximum which 
varied from 12 m. to 5 p. m., and decreased gradually from that time 
until daylight the following morning. In the 10 observations the maxi¬ 
mum amount of sugar in the leaves occurred in five cases at the same 
time, as the maximum amount of dry matter, while in the other five 
cases the maximum sugar content was reached at periods varying from 
one to six hours earlier than the maximum amount of dry matter. There 
is no evidence to show that there is any difference between com and 
the sorghums in regard to the time of day at which the maximum amount 
of sugar and dry matter may occur in the leaves. 
(4) The insoluble carbohydrates were estimated as starch according 
to the official method of acid hydrolysis and thus include besides starch 
the pentosans and other insoluble carbohydrates that are converted 
into reducing sugars by boiling with hydrochloric acid. The insoluble 
carbohydrates thus estimated generally reached a maximum later in the 
day than the sugars and after they had reached a maximum showed 
little decrease until about midnight, after which they decreased rapidly 
until daylight. The total increase in the dry matter of the leaves during 
the day could not be accounted for by the increase in the sugars and 
insoluble carbohydrates during the same period. The increase in the 
total sugars and insoluble carbohydrates in the leaves during the day 
only approximated from 46 to 92 per cent of the total increase in the 
dry matter of the leaves for the same period. 
(5) The nonreducing sugars in the leaves of the plants studied were, 
with the exception of the experiment with Dwarf milo and Red Amber 
sorgo, always in excess of the reducing sugars. The nonreducing sugars 
increased markedly during the day and decreased during the night, while 
the reducing sugars, as a rule, showed very little increase, and the 
amount present at the different periods of the day was very irregular. 
THe maximum increase in the reducing sugars in the leaves during the 
day in the case of com and milo only amounted to from one-tenth to 
one-third the increase in the nonreducing sugars. No significant dif¬ 
ferences were observed between corn and the sorghums in regard to the 
relationship between the reducing and nonreducing sugars in their leaves. 
literature CITED 
(1) Brown H. T., and Morris, G. H. 
1893. A CONTRIBUTION TO THE CHEMISTRY AND PHYSIOLOGY OP FOLIAGE LEAVES. 
In Jour. Chem. Soc. [London], v. 63, p. 604-677. Bibliography, p. 
674-677. 
(2) Colin, H., and Belval, H. 
1922. LA GENltSE DES HYDRATES DE CARBONE DANS LA BL$. PRESENCE DE 
l^vulosanes dans la tige. In Compt. Rend. Acad. Sci. [Paris], 
t. 175, p. 1441-1443. 
(3) Davis, W. A., Daish, A. J., and Sawyer, G. C. 
1916. STUDIES OP THE FORMATION AND TRANSLOCATION OP CARBOHYDRATES IN 
plants, i. the carbohydrates op the mangold leap. In Jour. Agr. 
Sci., v. 7, p. 255-326. References, p. 325-326. 
