39T] E. E. Free and S. F. Trelease 199 



Eate of growth and weight of dry matter produced was essen- 

 tially the same in all. All plants grew to maturity and 

 nearly all set seed. It appears that the degree of aeration of 

 the culture solution is without important influence on the 

 growth of buckwheat under the conditions described; a con- 

 clusion that may have value in general water-culture prac- 

 tice. ' 



It may be added that in the cultures treated with carbon 

 dioxide the plants sickened and wilted within a few hours 

 and died within a few days. In one case the stream of car- 

 bon dioxide was replaced after the first day by a stream of 

 air. In this case the plants recovered partially but remained 

 permanently smaller than the other plants of the experi- 

 ment. ! * 



THE EFFECTS OF CERTAIN MINERAL POISONS ON 



YOUNG WHEAT PLANTS IN THREE-SALT 



NUTRIENT SOLUTIONS 



By E. E. FREE and S. F. TRELEASE 



A large part of the experimentation which has been done 

 in the past on the effects of mineral poisons on plants is un- 

 satisfactory and contradictory, for the reason that the nutri- 

 ent materials available to the plants, in the soil or nutrient 

 solution employed, were different in the different experi- 

 ments. The reactions of plants to the various poisons appear 

 to vary with such differences in the available nutrients. In 

 connection with other work on nutrient solutions,, tests have 

 been made on the effects of certain poisonous elements on 

 the growth of young wheat plants in water-cultures. The 

 salt combination used in the nutrient solution was that found 

 by Shive * to be best for the production of dry weight of 



1 Shive, J. W., "A three-salt nutrient solution for plants." Amer. 

 Jour. Bot. 2: 157-160. 1915. Idem, "A study of physiological bal- 

 ance in nutrient media." Physiol. Res. I: 327-397. 1915. (Especi- 

 ally p. 352-364.) 



