Jan. io, 1914 
Drought-Resisting Adaptation in Maize 
297 
Table I. —Average measurements of seedlings of Chinese , Boone County White , and 
Navajo maize planted at different depths. 
Depth. 
Chinese. 
Boone County White. 
Navajo. 
Cole¬ 
op¬ 
tyle. 
Meso¬ 
cotyl. 
Coleop¬ 
tyle 
and 
meso¬ 
cotyl. 
Cole¬ 
op¬ 
tyle. 
Meso¬ 
cotyl. 
Coleop¬ 
tyle 
and 
meso¬ 
cotyl. 
Cole¬ 
op¬ 
tyle. 
Meso¬ 
cotyl. 
Coleop¬ 
tyle 
and 
meso¬ 
cotyl. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
2 
2 * 3 
2.3 
4.6 
3-7 
3 - 2 
6.9 
5-5 
5*0 
10. 5 
4 
2 - 5 
3 - 5 
6.0 
3 - 1 
4. 9 
8.0 
4-3 
6 * 5 
10. 8 
6 
2. 8 
5 -o 
7.8 
3-4 
6. 1 
9 - 5 
5- 2 
10. 2 
15*4 
8 
2 * 5 
S-* 
8.3 
2. 8 
7-4 
10. 2 
4-9 
11. 0 
i5-9 
IO 
3 - 2 
5-8 
8.9 
3 - 1 
8.6 
11. 7 
5-6 
12. 2 
17.8 
12 
4. 0 
5- 2 
9. 2 
3-4 
10. 4 
13-8 
5 -o 
*5- 1 
20. 1 
l6 
4. 6 
12. 4 
17 . O 
4. 3 
I 7* 5 
21. 8 
20 
4- 5 
IO. O 
15-4 
4. 7 
19. 7 
24. 4 
9. A 
5. 2 
23. 0 
28. 2 
28 
22 
5. 6 
26. 5 
32. 1 
6- 5 
29. 0 
35* 5 
Twelve cm. was the greatest depth from which seedlings of the Chinese 
variety appeared at the surface. Seedlings of Boone County White ap¬ 
peared from all depths up to 20 cm., while plants of Navajo maize 
appeared from all plantings, including the very deepest, 32 cm. 
There were numerous instances in which the combined length of the 
mesocotyl and coleoptyle was less than the depth at which the seed was 
planted. This, of course, means that the upper layers of the soil were 
penetrated by the true leaves. The maximum depth of soil thus pene¬ 
trated by the true leaves of the plants of the Chinese variety was 5 
cm. One plant of Boone County White maize forced its leaves through 
8 cm. of soil. In all of the Navajo plants the coleoptyle reached the 
surface. 
The extent to which the seedlings of the Chinese and Boone County 
White varieties were able to penetrate the soil by means of the true 
leaves was doubtless much greater in the carefully prepared soil of the 
experiment than it would be under field conditions, where any slightly 
compacted lump of soil would deflect the tender leaves and cause them 
to crumple. On the other hand, many seedlings failed to come up where 
there was less than 2 cm. between the top of the coleoptyle and the 
surface of the ground. The results clearly show that the coleoptyle 
is the proper organ for penetrating the soil, and where this office devolves 
upon the leaves there will be many plants that fail to reach the surface. 
It has been observed in many field plantings that the spatulate first 
leaf, formerly called the cotyledon, is the first evidence of the germinating 
plant. When this occurs in any considerable proportion of the plants, 
it is safe to assume that the seed has been planted too deep for the best 
results. 
