234 
The Philippine Journal of Science 
1916 
illumination was not much less than at midday, but the temper- 
ature was 4° or 5° lower. This experiment substantiates the 
opinion previously reached that illumination in itself is practi- 
cally without direct influence on the rate of growth ; but the same 
experiment demonstrates that temperature has great influence 
on growth, and suggests that an increase of 5°, say a change from 
26° to 31°, is sufficient almost to double the growth rate. 
A considerable number of measurements of growth by centi- 
meter zones were made in light and in darkness, using in all 
cases plants which were among the most rapid in their growth. 
The general result was that the plants in light had a considerably 
longer growing region, and that the region of most rapid growth 
was farther from the apex. A few illustrations will suffice to 
make this clear. 
Table VI . — Growth in millimeters of centimeter zones. 
Centimeter zone. 
May 18-19. 
College No. 88. 
May 9-10. 
College No. 88. 
May 9-10. 
College Mo. 331. 
May 18-19. 
College No. 960. 
In light. 
Dry 9. 
In dark- 
ness. 
Soil 2. 
In light. 
Dry 1. 
In dark- 
ness. 
Soil 3. 
In light. 
Dry 6. 
In dark- 
ness. 
Soil 1. 
In light. 
Soil 6. 
In dark- 
ness. 
Soil 2. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
1 
5 
8 
3 
7 
3.5 
6 
1 o I 
2 
8 
14 
10 
14 
5.5 
7 
1 3 1 
3 
3—_ - 
7 
17 
10 
16 
10 
9 
2 
13 
4 
4.5 
20 
12 
8 
10 
16 
2 
3.5 
6 
4 
16 
10 
3 
11 
19 
2 
2 
6 
4 
13 
9 
0.5 
12 
17 
2 
0.5 
7 
3.5 
12 
7 
0.5 
12.5 
10 
2 
8 
4.5 
9 
4 
10 
9 
2 
9 
3 
8 
4 
10.5 
8 
1.5 
10 
2.5 
7 
3 
10 
5 
1.5 
11 
2.5 
4.6 
4 
10 
3.6 
i 
12 
3 
3 
3.6 
8 
1.5 
i 
13 
2 
2 
3 
8 
1.5 
i 
14. 
1.5 
2 
2.5 
7 
1 
0.5 
15 _ 
1.5 
1 
3 
6 
0.5 
16. _ 
1 
0.6 
3 
4.5 
17 
1 
3 
4.5 
18 
i 
2.5 
4 
19 
1 
3 
3 
20 
0.5 
2.5 
3 
21 
0.5 
3 
2 
22 
0.5 
2 
1.5 
23 
0.5 
2 
0.5 
24 
0.5 
2 
26 
2 
26 
1 
27 
1 
28 
1 
