740 
Journal of Agricultural Research 
Vol. XXXI, No. 8 
Table VI. — Concentration of the expressed cell sap 
Age of 
plants 
(days) 
Length in centi¬ 
meters 
Dry weight 
in grams 
Freezing 
point of 
expressed 
juice, 
depression 
in °C. 
Osmotic 
pressure 
in atmos¬ 
pheres 
Tops 
Roots 
2 
0.15 
0.7 
0.0257 
0.8910 
10.73 
3 
.50 
1.5 
.0247 
.8135 
9.795 
4 
1.40 
5.2 
.0244 
.676 
8.021 
5 
3.00 
6.3 
.0225 
.646 
7.76 
6 
4.7 
8.0 
.0196 
.5877 
7.08 
7 
6.5 
10.6 
.0199 
.552 
6.65 
8 
8.5 
14.4 
.0178 
.4995 
6.02 
9 
9.4 
15.6 
. 01939 
. 4555 
5.367 
10 
11.5 
16.3 
. 01905 
.4205 
5.068 
11 
11.7 
16.3 
.0193 
.4170 
5.026 
12 
12.2 
18.5 
.0201 
.4245 
5.116 
13 
13.2 
20.0 
.0195 
.4030 
4.857 
14 
13.6 
19.5 
.0210 
.4275 
5.272 
15 
16.4 
20.9 
.0209 
.445 
5.362 
25 
i 
19.5 
27.8 
.0396 
.497 
5.99 
If one follows in Table VI or Figure 4 the depression of the freezing 
point of the cell sap of wheat seedlings, it will be noticed that there is a 
Fig. 4.—Length of roots and plumules, in millimeters; and freezing-point depression of the cell sap, 
in degrees 
gradual decrease from the 2-day-old plants to about the 12-day-old 
plant stage, after which the osmotic pressure becomes greater. The de- 
S ression of the freezing point is obviously due to the factors already 
iscussed—namely, the amount of water and soluble substances. The 
amount of moisture becomes greater after the 2-day stage, which 
tends to decrease the osmotic pressure. The r6les played by the sugar 
and ash elements reach their maximum values at different stages. 
In the 3-day stage the ash is very high, being nearly 2 per cent of the 
moisture content; the sugar is lower at the 3-day stage than at the 
6-day stage. The percentage of ash, based on moisture content, 
drops from the 2-day-old stage to the 9-dav-old stage, from which 
point there is a continual increase. The sugars gradually but con¬ 
tinuously decline in percentage. Bakke’s ( 1) work indicates by the 
rate of transpiration that the plant contains more water in the morn- 
