492 
ME. J. B. LAWES, BE. GILBEET, AND DE. PTJGH ON 
Experiments^ Series 6. 
In order to bring out more clearly the influence of sunlight before the exhaustion, a 
series of experiments were made, in which two vessels, containing the duplicate quan- 
tities of plant, were each kept covered with paper for some time, and then, from twenty 
to thirty minutes before commencing the exhaustion, the paper was removed from one of 
them, both being then exhausted, — the process continuing ten, fifteen, or twenty minutes. 
The following results were obtained. 
Table VI. — Showing the amount and composition of the Gas evolved into a Torricellian 
vacuum, by duplicate quantities of plant, both kept in the dark for some time, and 
then one exposed to sunlight for about twenty minutes, when both were submitted 
to exhaustion. 
Per cent. 
Date. 
Description 
of Plant. 
Conditions dimng 
Exhaustion. 
Total G-as 
collected. 
Nitrogen. 
Oxygen. 
Carbonic 
acid. 
Oxygen and 
Carbonic 
acid. 
July 31. 
Oats 
f In dark 
cub. cents. 
24-0 
77-08 
3-75 
19-17 
22-92 
1 In sunlight ... 
34-5 
68-69 
24-93 
6-38 
; 31-31 
Aug. 2 . 
Oats 
r In dark 
18-6 
68-28 
10-21 
21-51 
31-72 
\ In sunlight ... 
39*2 
67-86 
25-25 
6-89 
32-14 
Aug. 2. 
Oats 
r In dark 
30-7 
26-3 
76 87 
8-14 
14-99 
23-13 
fin sunlight ... 
69-43 
27-17 
3-40 
30-57 
Aug. 2. 
Oats 
f In dark 
17-0 
79-41 
7-65 
12-94 
20-59 
\ In sunlight ... 
28-6 
76-22 
18-53 
5-25 
23-78 
Aug. 3. 
Oats 
f In dark 
29-8 
81-88 
6-38 
11-74 
18-12 
\ln sunlight ... 
32-1 
66-36 
30^53 
3-11 
33-64 
Aug. 3. 
Oats 
f In dark 
11-6 
65-52 
6-90 
27-58 
34-48 
I In sunlight ... 
23-1 
70-56 
20-35 
9-09 
29-44 
Aug. 3. 
Oats 
J In dark 
17-0 
80-00 
5-88 
14-12 
20-00 
t In sunlight ... 
19-7 
73-10 
22-33 
4-57 
26-90 
The comparison of the results in this Table with those in Table V,, shows that the 
oxygen must have been liberated from the carbon, and been retained within the cells, 
until the instant of the exhaustion, as the gas was evolved from all parts of the leaf, 
and not from the surrounding water, as soon as the pressure was removed. 
The conclusions to be drawn from the above several Series of experiments are not 
without an interesting bearing upon our present subject. 
1. Carbonic acid, within growing vegetable cells, and intercellular passages, which 
are penetrated by the sun’s rays, suffers decomposition with the evolution of oxygen, 
the latter remaining in the plant or being evolved from it. This takes place very 
rapidly after the penetration of the sun’s rays. 
