1920] 
DUGGAR—H-ION CONCENTRATION AND NUTRIENT SOLUTIONS 17 
TABLE VI 
(Series 2, Peas) 
SALT REQUIREMENTS AND H-ION CONCENTRATION IN RELATION TO GROWTH 
Total | Gr. wt. | Total | Greatest Pa 
No. re gr. of roots | dry wt. | length 
COUPS | (gms) | (gms) | (gms) | (em.) | Initial [After gr. 
1 ApO 16.01 5.29 1.351 24.02 3.4 4.6 
2 Ap /10 17.89 6.21 1.473 22.72 5.8 5.8 
3 Ap /20 15.34 | 5.30 1.332 19.93 6.3 6.0 
4 Ap /40 11.55 | 4.68 1.124 12.49 E 6.8 
5 ApNa 20.30 | 7.20 1.603 26 .03 3.45 4.4 
6 ApM 18.28 | 6.15 1.418 24.19 5.4 6.4 
7 Ap 1/ 19.39 | 6.60 1.505 24.50 3.35 4.6 
8 Ap 3/ 14.17 5.22 1.262 21.13 3.15 4.2 
9 BpO 15.91 5.70 1.326 19.59 6.6 6.2 
10 Bp 1/ 16.69 6.13 1.410 22.16 6.4 6.0 
11 Bp 2/ 16.58 | 5.82 1.391 22.48 5.6 6.0 
12 Bp 5/ 15.78 | 5.33 1.316 20.24 9.2 4.6 
13 BpK;/10 16.12 5.91 1.413 19.01 7.0 6.6 
14 BpK /10 18.75 | 6.87 1.501 21.33 5.2 
15 pCa 17.15 | 6.18 1.393 23.44 7.3 8.0 
16 Bp /5 17.49 | 6.32 1.389 19.21 7.4 7.4 
17 Bp /10 18.38 | 6.29 1.413 21.65 8.6 8.0 
* Heavy precipitate. 
use of a new supply of monobasic potassium phosphate. This 
was a high-grade reagent, but was not guaranteed free of phos- 
phoric acid, and no such guaranteed salt was then obtainable. 
The determinations indicate very clearly that attention must be 
paid to the determinations of the Px value whenever such experi- 
ments on nutrition are conducted. This series of experiments 
must be examined and interpreted in the light of the Py value 
referred to. Nevertheless, it should be pointed out here, though 
emphasized later, that the Pa exponent of the more acid solu- 
tions is rapidly increased with the growth of the crop. The 
increased acidity is doubtless due to an excess of acid in the 
preparation of the salt. This relatively high acidity affected, 
of course, to a degree the Py of other solutions to which alkali 
was added. 
In general, this series is an extension and continuation of the 
previous work, modified partieularly by the addition of certain 
2 
