1920] 
DUGGAR—H-ION CONCENTRATION AND NUTRIENT SOLUTIONS 15 
TABLE IV 
(Series 2, Wheat) 
SALT REQUIREMENTS AND H-ION CONCENTRATION IN RELATION TO GROWTH 
Total Total Greatest s 
No. Culture gr. wt. dry wt. length Initial Pa 
indices oak ) (gms.) (cm.) ol. 
1 AwO 4.39 545 24.37 3.4 
2 Aw /10 5.30 611 24.75 5.8 
3 Aw /20 4.56 533 22.74 6.3 
4 Aw /40 3.21 431 19.80 + 
5 AwNa 4.86 556 25.01 3.45 
6 AwM 5.93 542 23.04 5.4 
7 Aw 1/ 5.21 .569 24.63 3.35 
8 Aw 3/ 1.79 .306 16.38 3.15 
9 BwO 6.07 503 21.86 6.6 
10 Bw 1/ 7.76 625 23.96 6.4 
11 Bw 2/ 7.82 657 24.40 5.6 
12 Bw 5/ 4.96 500 21.81 8.2 
13 BwK;/10 7.60 623 26.18 7.0 
14 BwK /10 7.51 602 25.45 
15 BwCa 8.67 810 25.32 7.3 
16 Bw /5 6.75 570 23.24 7.4 
17 Bw /10 7.08 606 24.49 8.6 
* Heavy precipitate. 
and the number of points in the curves above or below the base 
lines indicates for each crop, under the conditions reported, the 
relative increase or decrease in green weight. 
The change in the Py of the solutions occurring as a result of 
contact with the roots was followed only in the case of corn. 
As a rule, in the more acid solutions the reaction is shifted some- 
what towards neutrality, but irregularities occur in solution B, 
some of which may be related to changes not due to the inter- 
change of ions between roots and solution. 
The second series of experiments, the results of which are 
included in tables rv, v, and vr, also plotted in fig. 2, was carried 
through during late November and early December. The con- 
ditions were much the same in general as those prevailing during 
the earlier work. "There was this difference, however, that while 
the first serles was placed on latticed tables in greenhouses with 
proper spacing to provide for favorable and uniform condi- 
