Mar. s, 1924 Carbohydrate Variations in Corn and Sorghum Leaves 787 
been removed, were ground in a food chopper. The ground material 
was immediately placed in three times its volume of 95 per cent ethyl 
alcohol and sealed in glass jars. The time required to collect the ma¬ 
terial in this manner at each two-hour period approximated 15 to 20 
minutes. At a convenient time the alcoholic material was placed in a 
hot-air oven and dried for 24 hours at a temperature of ioo° to 105 0 C. 
The material was then placed in sealed glass jars until the chemical 
determinations could be made. 
Table I .—Moisture content of the soil at the time of leaf sampling in igi 6 and igiy at 
Garden City, Kans., and in igig at Manhattan, Kans. 
Percentage of moisture at a depth of— 
Date. 
Com plot: 
July 20, 1916. 
August 1, 1916. . . . > 
Wilting coefficient... 
Milo plot: 
July 20, 1916... 
August 1, 1916. 
Wilting coefficient... 
Corn plot: 
July 25, 1917. 
Wilting coefficient... 
Milo plot: 
July 25, 1917. 
Wilting coefficient... 
Corn and sorghum plots: 
July 17, 1919. 
Wilting coefficient... 
I foot. 
2 feet. 
3 feet. 
4 feet. 
5 feet. 
6 feet. 
10.0 
14.7 
19.0 
21.9 
23.6 
24.2 
7-3 
11.8 
14.0 
18.1 
21.4 
22.0 
12.3 
15-9 
12.4 
15.O 
16.3 
16.4 
11.1 
15-4 
19.6 
22.2 
24.1 
24.8 
8-3 
9.9 
14.6 
14.9 
20.8 
24.0 
12.2 
13-4 
1 5- 1 
14-3 
15-4 
15.6 
11.2 
11.6 
18.4 
19-3 
23.1 
22.3 
12.6 
12.2. 
• 15-3 
J 3-9 
16.9 
17.8 
1 8.8 
18.0 
19.2 
19.7 
21.6 
21.6 
12.3 
15-9 
12.4. 
16.3 
16.4 
t -i 
i l6. C 
21.6 
•22.1 
21.4 
12.2 
1 
12.5 
12. I 
* • *r 
12.7 
actual, amount of constituents 
Since the dry weight of a green leaf fluctuates through a considerable 
range during a 24-hour period, the analyses of leaf material expressed in 
percentage of dry weight only approximates the changes that occur 
in the leaf during a given period. The changes in the various constitu¬ 
ents of the leaf may be followed more accurately by the determination 
of the dry weight of a unit of leaf area for each period that analyses are 
made, and from the percentage data for that period determine the actual 
amount of the various constituents in any unit of leaf area. The dry 
weight of a unit of leaf area at the close of each of the two-hour periods 
during the experiments was determined by the method previously de¬ 
scribed by the writer (10 ), and the amount of each of the constituents 
was expressed in grams per square meter of leaf. 
CHEMICAL, METHODS 
The carbohydrates were estimated according to the methods of the 
Association of Official Agricultural Chemists. 4 In 1916 and 1917 the 
nonreducing sugars were determined by the difference between the total 
4 Association of Official Agricultural Chemists. Official and tentative methods of analysi s. 
As compiled by the Committee on Revision of Methods. Revised to Nov. i, 1919. 417 P-* 18 fig. Wash¬ 
ington, D. C. 1920. Bibliographies at ends of chapters. 
