Jan., 1923] BAKKE AND ERDMAN-CULTURES OF MARQUIS WHEAT 
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the plants was considerably greater for the sand cultures than for the 
solution cultures. 
Meier and Halstead (14) ran a series of wheat experiments with Shive’s 
three-salt solution, each series comprising 21 cultures of different salt 
proportions all having an osmotic concentration of one atmosphere. They 
found that no one culture gave consistently high yields of plants, and noted, 
as did Livingston (6), Shive (19), McCall (10), Wolkoff (27), and others, 
that the total amount of transpiration is as good a criterion as is the final 
dry weight of plants for studying the comparative growth obtained in 
different solutions. 
Bouyoucos (1) observed that the amount of transpiration per gram of 
dry matter tended to be larger in the sand than in solution cultures receiving 
the same densities of solution, while the actual dry matter produced was 
greater in the solution than in the sand cultures. Lyon and Bizzell (9) 
found that wheat seedlings growing in crushed quartz containing the same 
nutrient solutions as those used in water cultures produced the same relative 
quantities of dry matter per unit of transpiration as did the water cultures, 
but the quantitative production of dry matter per unit of transpiration was 
in each case greater in the quartz than in the water cultures. 
Certain investigators, McCall (10), Lyon and Bizzell (9), and others, 
claim that the superiority of sand cultures over solution cultures is due 
primarily to the adsorptive properties of the sand particles. Wolkoff (27) 
concluded from his work that adsorption was not the factor which modified 
the concentration of the solution to such an extent as to cause even slight 
differences in plant growth. Shive (21) also found no evidence of the 
adsorption of salts or ions in sufficient amounts to change the total concen¬ 
tration of the solutions. 
In recent years considerable attention has been devoted to studying the 
effect of the reaction of the medium of sand and water cultures on the growth 
of plants. Hoagland (4) studied the effect of hydrogen- and hydroxyl-ion 
concentration on barley seedlings growing in partial nutrient solutions of 
like osmotic pressure. He noted that the OH ion was more toxic than the 
H ion for similar divergencies from the neutral point. Later the same author 
(5) found that an acid solution (pH 5) was not injurious to the barley plant 
at any period in its growth. As in his previous work, he observed a tend¬ 
ency on the part of the plant to adjust the reaction of the medium toward 
the neutral point. Toole and Tottingham (24) also noted that barley 
seedlings had a marked neutralizing effect on the nutrient solution, and 
that the solution in which the plants had been grown showed a more nearly 
uniform hydrogen-ion concentration than did the original solution. They 
found that the weights of dry tops of barley were inversely proportional to 
the hydrogen-ion concentration of the solution. 
Duggar (2) concluded from his work that the tendency for the shifting 
of an acid reaction toward the neutral point depends in part upon the 
