Sept, is, *923 Acidity of Corn and its Relation to Vegetative Vigor 461 
five plants for each sample. There were not enough plants of No. 113 
for even one determination. The results are given in Table III. 
Table III .—Acidity of the tops of corn plants of Series III, 44 to 56 days old, in very poor 
condition, grown in the same soil as Series II 1 
Strain No. 
Date of 
determina¬ 
tion (July, 
1922). 
Titratable 
acidity (cc. 
N/ 2 oNaOH). 
P» 
Specific 
gravity. 
J 8 
6.9 
5 - 23 
I. 0246 
l 8 
( 9 - 2 ) 
(5- 22) 
(1-0253) 
i 
jQ it 
7 7 
9.4 
5-°3 
I. 0221 
i 
i 
l 18 
(12.3) 
( 5 .oi) 
(i. 020l) 
35 °. 
7 
9*5 
5. 16 
I. 0232 
15 ° . 
6 
10. 2 
5. 10 
( 3 ) 
139. 
14 
10. 6 
5 - i 3 
I. 0248 
315 . .••• 
II 
10. 8 
5. 06 
J -°*94 
f 6 
11. 0 
5.10 
( 2 ) 
31 .1 
I 
(13-2) 
( 5 - 01) 
(1. 0272) 
3*6 . 
l8 
11. 7 
S-03 
1. 0246 
972 . 
14 
12.3 
4-97 
1. 0247 
Average. 
.1 103 
5 -°9 
1. 0233 
1 Figures in parentheses are from the poorest, most spindling plants, not typical of the row, deter¬ 
mined separately and not included in the averages, but given to show the greater acidity of the less 
vigorous plants. 
• Not enough juice for determinations. 
Comparison of the results reported in Table III with those in Table II 
shows that the plants have a markedly increased titratable acidity and 
hydrogen-ion concentration, although grown in the same soil. But these 
plants grew more slowly and were more spindling than their predecessors, 
besides showing an abnormal dying of the tips of the leaves. In Table III, 
as in the two preceding tables, are given in parentheses the values ob¬ 
tained from the poorer plants of each group which obviously were below 
the average in vigor. These data afford additional evidence of an inter¬ 
relation of vigor and acid accumulation. 
SERIES IV 
The fourth series was a repetition of the first in the original greenhouse 
to see whether, on second trial, the growth conditions there would again 
produce the more vigorous, rapidly growing plants with their compara¬ 
tively low acidities. Unused soil adjacent to that of the first plot was 
used for Series IV. A redetermination of the soil reaction showed that 
the soil on this bench remained approximately neutral, P H 7.2. 
The higher temperatures of June and July, as compared with those of 
April and May, probably were responsible for the fact that the plants of 
this series made an even more rapid growth than did those of Series I. 
At the end of only five weeks their average height was 80 cm. and their 
average green weight 126 gm. as compared with 50 cm. and 44 gm., the 
corresponding measurements for the unhealthy Series III at the age of 
seven weeks. The data are given in Table IV. 
