I2 BOTANICAL GAZETTE ' [jury 
apparatus would in no way change the nature of the conclusions 
to be drawn from the results. 
IV. Experimental results 
A. MEASUREMENT OF THE SEEDS.—The measurement of the 
internal forces of Xanthium seeds by means of NaCl and LiCl 
solutions has been repeated and extended with full confirmation 
of the previously published results. The data are presented in 
tabular form for the sake of convenience in table III, and these 
figures may serve as a basis of comparison in the soil experiments, 
where the surface forces of the soil particles, instead of osmotic 
pressure, are pitted against the internal forces of the seed. The 
data were secured with the lower seeds of Xanthium pennsylvanicum. 
TABLE III 
MOISTURE INTAKE OF Xanthium SEEDS IN OSMOTIC SOLUTIONS; TEMPERATURE 
23.5° C.; INTAKE IN PERCENTAGE OF AIR-DRY WEIGHT 
motic 
sygg Oh micre thour | 4hours | 7 hours | rohours | 24 hours | 48 hours ehomtocig . 
pheres 
BuO ek 16.30 | 44.35 | 48.78 | 50.38 | §2.18 | 51.58 0.0 
0.1 M-NaCl....| 16.79 | 39.43 | 45.87 | 46.48 | 46.39 | 46.33 3.8 
o.2M-NaCl.. 17.12 | 38.67 | 45. 45-57 | 45.93 | 45-52 7.6 
o.3 M-NaCl 10.07 | 34.06 | 40.75 | 43.65 | 426241 42.05 Ti-4 
0.4 M-NaCl 44.30) §8, 01 1 96.08 | 30:07:-1 40.33 | 40:27 15.2 
o.5 M-NaCl 13.96 | 30.26 | 35.87 | 38.08 | 38.70 | 38.98 19.0 
0.6 M-NaCl TS OS oa eS ft Rea Es Sr 1 9 7 1 S838 22.8 
0.7 M-NaCl %3.32 96.29 | 30.90 | 33.73 | 92.90. | $2.95 26.6 
0.8 M-NaCl 45.15 | 25.99 (96.99 1° 20.65 TSE et are 30.4 
o.9 M-NaCl 12.58 | 24:34) 27.64 | 98.95) 26.%4 1 20-70 34.2 
1.0 M-NaCl EY.00.| 227.92 25.42 26.48 26.21 26.73 38.0 
2.0 M-NaCl S.40 | 14.56 | 18-98 1S 43 | £6.00 | 16.65 72.0 
4.0 M-NaCl 4.81 8.37 9.84 | 10.08| 11.00] 11.76| 130.0 
Sat. —NaC 3-42 4.04 | 5-34 5.84 | 6.21 6.35 | 375-9 
mat. -LICl:. J; —0.67 | —0.77 | —0.58 | —0.58 | —0.58 | —0.29 | 965.0 
The results obtained by the vapor pressure method over sul- 
phuric acid are shown in table IV, and some of the curves of 
moisture intake showing the point of natural equilibrium are shown 
in figs. 2 and 3. 
As the table and curves show, the seeds are initially in moisture 
equilibrium with sulphuric acid of 46-54 per cent strength. In 
general the seeds which have carbohydrate reserves in greatest 
