354 



THE EFFECT OF WATER UPON GROWTH [Cn. XII 



GAIN ('92, '95), who studied the effect upon the entire plant, 

 so that his results are of especial interest here. 



GAIN planted seeds of various species in sand to which a little garden 

 loam had been added. He was careful either to select seeds of equal size or, 

 after sprouting had occurred, to weed out all but the normal, medium-sized 

 ones. In one set of experiments, the soil contained from 3% to 6% of 

 water; in the other, from 12% to 16%. 



GAIN found that the entire plant grew faster in the humid 

 than in the dry soil, as the accompanying diagram, Fig. 97, 



25 

 GR 



20 

 GR. 



1.5 

 GR. 



1.0 

 GR. 



0.5 

 GR. 



I MAY 



1 JUNE 



1 JULV 



FIG. 97. Curves of fresh weight of two similar seedlings of flax, one growing in 

 moist, the other in dry, soil. The maximum weight (M ) gained by the plant 

 differs in the two cases, and also the time of gaining that weight. F, time of 

 flowering ; /m, time of fructification. (From GAIN, '95.) 



indicates. The aerial parts of the plant are more affected than 

 the subterranean. The ratio of growth of plants in moist soil 

 to those in dry varied from 1.12 (radish) to 2.33 (bean). 



