1 82 
ALFRED DACHNOWSKI AND R. GORMLEY 
decrease in weight increment may arise through faulty nutrition and 
enforce compensating processes. 
8. Weaker acid solutions are more effective in increasing the hydra- 
tion capacity of tissues than stronger concentrations of acids, and 
thus are more efficient in increasing (stimulating) transpiration but not 
the growth of plants. The variations cannot always be attributed 
to differences in the absorptive surface of the root system. But 
whether the variations in the amount of water absorbed and held by 
tissues are essentially an expression of their colloidal state, or of ion 
concentration (osmotic pressure) , or connected with hydrolytic reac- 
tions and hence with metabolism, needs further inquiry. 
9. The amount of water retained within the plant and involved 
in metabolism and in the growth increment should be known as the 
physiological water requirement, to distinguish it from the other 
term used on the basis of the environmental water relation of the plant. 
Table VII 
Transpiration and Growth of Coleus sp. in Glycocoll Solutions 
December 17, 1913, to March i, 1914 
Culture solution 
Amount of water in grams 
Absorbed I Transpired Retained 
1. Distilled water. . 
2. w/800 glycocoll. . 
3. w/i, 600 glycocoll 
4. w/3,200 glycocoll 
5. w/6,400 glycocoll 
14.70 
21.50 
25-50 
45.00 
7.20 
10.00 
23.70 
34.20 
9.80 
22.60 
27.40 
32.40 
30.60 
15.60 
23.60 
23.00 
50.80 
25.20 
52.30 
30.30 
13.65 
21.10 
25.20 
46.60 
7.00 
9.80 
23.20 
35-10 
9.80 
21.90 
27.40 
33-00 
30.10 
15.10 
23.20 
24.70 
49.60 
24-50 
53-00 
31-50 
1-15 
0.40 
0.30 
— 1.60 
0.20 
0.20 
0.50 
—0.90 
0.00 
0.70 
0.00 
—0.60 
0.50 
0.50 
0.40 
-1.70 
1.20 
0.70 
— 0.70 
-1.30 
Gain or loss in weight 
of plants (in grams) 
1.95 
— 1.60 
I-I3 
— 0.90 
0.85 
— 0.60 
1.52 
-1.70 
2.72 
— 2.00 
Immersed portions of stem show strong curvature. Root growth best in solu- 
tion No. 3. Leaves reduced in size in strong solutions; vary in form in the weaker 
solutions. Atmospheric conditions up to January 17, as in Table I. 
