[VoL. 7 
32 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
| TABLE XVI 
(Series 4, III—Corn [dry, high temperature]) 
SALT REQUIREMENTS AND H-ION CONCENTRATION IN RELATION TO GROWTH 
Total | Gr. wt. | Total | Greatest Pu 
No. Culture gr. wt. | of roots | dry wt. | length 
indices 
T (gms.) | (gms.) | (gms.) | (cm.) | Initial | After gr. 
1 AcO 24.43 8.59 1.812 24.35 3.4 5.9 
2 Ac /5 25.90 | 7.94 1.751 22.81 4.6 6.0 
3 Ac /10 17.22| 5.28 1.360 27.64 5.8 6.2 
4 Ac 1/ 21.80 5.60 1.667 31.24 3.35 4.0 
5 Ac 3/ 17.49 | 4.61 1.405 23.65 3.15 4.6 
6 AcNa 16.00 | 4.70 1.231 27:17 3.45 5.6 
7 AcM 30.41 9.61 2.014 32.26 5.4 6.2 
8 BcO 19.89 6.30 1.604 27 .07 6.6 4.0 
9 Be /5 20.89 7.11 1.756 29.80 7.4 6.8 
10 Be /10 20.90 5.85 1.810 30.41 8.6 6.8 
11 Be 1/ 23.00 9.25 1.637 27.75 6.4 5.0 
12 Be 5/ 20.02 7.70 1.442 29.59 3.2 4.2 
13 Bc 10/ 1.64 .48 285 5.11 2.8 3.4 
14 BcK, /10 24.52 9.89 1.665 31.33 7.0 5.2 
15 cCa 23.44 8.81 1.867 32.53 7.3 7.8 
16 CcO 16.62 4.97 1.125 25.67 4.2 7.8 
17 Ce /5 18.52 5.20 1.180 32.71 6.4 8.0 
18 Ce /20 11.28 4.06 835 14.88 150 8.0 
19 Ce 1/ 20.56 5.65 1.407 29.97 3.6 7.9 
20 Ce 5/ 8.63 1.61 856 20.75 3.2 7.6 
21 CeNa 15.54 5.57 1.122 25.31 4.2 7.8 
largely an increase in the growth of roots. It is perhaps possible 
that the partial shade of this series referred to above has been a 
factor in the irregularities which prevail throughout. There is 
no basis on which to explain the growth in AcNa. Turning, 
however, to table xv, indicating the results with corn grown at 
low temperature and higher humidity the data are notably 
different from the preceding. In this case the most favorable 
medium is culture BcK;/10, rather closely followed by CcO and 
less closely by Be5/. In this section it is also notable that the 
maximum root growth occurs over a range of hydrogen ion 
concentration from 4.2 to 8.6. Exclusive of culture CcO the 
higher growth quantities are obtained for the different solutions 
at relatively low hydrogen ion concentration, that is, with media 
approaching neutrality more or less. This is particularly ob- 
