EFFECT CW TRANSPIRATION. 13 



cells of the same plants grown in the soil containing 1 per cent total 

 salts (estimated 0.7 per cent of sodium chlorid . The height (average 

 for all three species) of the cells on the upper leaf surface of the con- 

 trol plants is about 33 per cent and that on the lower surface about 

 26 per cent greater than that of the plants grown in a soil containing 

 1 per cent of total salts. 



A comparison of the height of the epidermal cells of plants grown 

 in nonsaline soils and in soils containing 2 per cent of total salts 

 (estimated 1.4 per cent of sodium chlorid) shows even more striking 

 differences. The height of the epidermal cells on the upper leaf sur- 

 faces (average for all three species) is 51 per cent and on the lower 

 surface 76 per cent greater in the control plants than in plants of the 

 same species grown in a soil containing 2 per cent of total salts. 



EFFECT OF A MIXTURE OF SOLUBLE SALTS, PRINCIPALLY 

 SODIUM CHLORID, ON TRANSPIRATION. 



EFFECT OF SALTS WHEN PRESENT IX SUFFICIENT QUANTITY TO PRO- 

 DUCE BLOOM. 



Wheat (Trlticum durum) was germinated and grown in a natural 

 saline soil containing 1.5 per cent of total soluble salts (estimated to 

 contain 1 per cent of sodium chlorid), where the plants soon became 

 covered with a copious bloom, and in a nonsaline soil as a control, 

 where the bloom was inconspicuous. When the plants were about 

 6 inches high the leaves were detached and their cut surfaces were 

 sealed by dipping in melted paraffin. They were then weighed at 

 frequent intervals during a period of several hours, several leaves 

 from the plants grown in saline soil being weighed together and 

 several from the controls. All the leaves in each experiment were 

 kept between weighings under uniform conditions as to heat, light, 

 and moisture. The loss recorded at each weighing was taken as a 

 measure of the amount of water transpired. 



" In the first experiment of this series the total initial weights of the 

 leaves from plants grown in the saline soil and of those from the con- 

 trol plants were respectively 221 and 262 milligrams. After an 

 exposure of twenty-one hours to the atmosphere of an ordinary room 

 the weights were respectively 191 and 197 mg. : hence the leaves from 

 plants grown in the saline soil lost 13.6 and those from the control 

 plant 24.8 per cent of their original weights. An even greater 

 difference was shown in a second experiment. In this the leaves 

 from plants grown in the saline soil weighed at the beginning 377 mg. 

 and the control 506 mg. The former lost 59 mg. and the latter 24"> 

 mg. in nineteen hours, or about 16 per cent and 48 per cent , respectively. 



