The Reversal of Geotropic Response in the Stem 119 
Date of 
experiment 
Number 
of 
seedlings 
Number of 
seedlings 
showing 
curvature 
Volume 
of jar 
in c.c. 
% co 2 
(by 
analysis) 
Tempera¬ 
ture 0 C. 
1. 1st Dec. ... 
5 
5 down 
4000 
33 
14 
2. nthFeb. ... 
7 
7 » 
7000 
32 
12 
3. nth Feb. ... 
9 
9 „ 
7000 
29-7 
12 
4. 17th Jan. ... 
3 
3 „ 
4000 
26 
13 
5. 19th Nov_ 
3 
3 
4000 
25 
14 
6. nth Feb.... 
4 
4 
7000 
22 
12 
7. 25th Nov.... 
3 
3 » 
4000 
20*9 
14 
8. 30th Jan. ... 
2 
2 ,, 
9000 
20 
13 
9. 19th Jan. ... 
5 
5 „ 
4000 
19-6 
13 
10. 1st March... 
5 
5 » 
7000 
18 
12 
n. 27th Tan. ... 
2 
2 ,, 
9000 
i6-8 
14 
12. 22nd Nov. 
7 
6 „ 
4000 
16 
T 4 
13. 21st Jan. ... 
5 
5 „ 
4000 
14-5 
13 
14. 7th Feb. ... 
3 
3 » 
7000 
14 
n 
15. 7th Feb. ... 
10 
9 » 
7000 
13-3 
n 
16. 20th Jan. ... 
4 
4 » 
5500 
12-6 
14 
17. 21st Feb. ... 
2 
2 ,, 
7000 
10-5 
13 
18. 18th April 
7 
7 » 
7000 
10-4 
14 
19. istFeb. ... 
2 
2 ,, 
4000 
10*3 
1.3 
20. 14th March 
6 
6 up 
7000 
9 
14 
21. istFeb. ... 
2 
2 down. 
4000 
9 
14 
22. 14th March 
7 
7 up 
7000 
8-2 
14 
23. 25th Feb.... 
4 
4 down 
7000 
8 
14 
24. 10th March 
7 { 
1 down 
6 up 
| 7000 
7*9 
13 
25. nth March 
7 
7 up 
6250 
7*76 
I 5'5 
26. 16th March 
9 
9 „ 
7000 
7-6 
14 
27. 21st Feb. ... 
2 
2 down 
7000 
7*4 
M 
28. 17th Feb. ... 
9 
9 up 
7000 
7*2 
14 
29. 15th March 
7 
7 » 
7000 
7 -i 
M 
30. 25th Feb. ... 
5 
5 » 
6250 
7 
14 
31. 25th Feb.... 
8 
8 „ 
9000 
6 
14 
32. 14th Feb— 
2 
2 ,, 
7000 
5-2 
13 
33. 15th March 
9 
1 
9 „ 
7000 
5-2 
14 
NOTES ON EXPERIMENTS 
Exp. 1. The box containing the seedlings was removed from the 
jar on Dec. 2nd and was left horizontally in fresh air and light 
with the hypocotyls of the seedlings still showing the strong down¬ 
ward curvature. On Dec. 3rd all the seedlings showed a normal 
negatively geotropic curvature. This complete recovery was brought 
about because photosynthesis was carried on when the seedlings 
were in ordinary air and light, and thus the accumulated carbon 
dioxide was used up, the hypocotyls became again relatively alkaline 
and normal upward curvature resulted. 
