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demonstrate, as the C 0 2 -number for the whole two-hour reading may 
be quite low. Even when the two-hour reading, immediately after chloro¬ 
form, shows a fair augmentation over the normal respiration, yet if the 
outburst lasted only one hour then the curve of two-hour readings would 
not show so sharp a peak as a curve of one-hour readings. Still shorter 
readings might show an even more acute and high peak. Exp. XIII was 
intended to bring out the intensity and brevity of the outburst of C 0 2 
following a suitable dose of chloro¬ 
form. A series of one-hour readings 
with a group of six Cherry Laurel 
leaves, weighing 13-82 grms., was 
started, and after five readings of 
normal respiration, 0-63 c.c. of chloro¬ 
form per litre of air-current was given. 
Fig. 15 shows the result. The C 0 2 - 
output for one hour rises to 0.0063, 
just three times the normal respira¬ 
tion in the previous hour, and then 
falls off rapidly. Had two-hour 
readings been taken, the peak after 
chloroform would have only attained 
0-0052, not more than double the 
normal, as in Exp. X. 
Fig. 15 is not comparable with 
the other figures as regards the 
slope of the curve, as the abscissae 
are here extended to double. 
Exp. XIV was intended to throw 
light on another particular point. 
It was just possible that the fall 
in the output of C 0 2 , after chloroform 
had been given to the leaves, might 
be due to the closure of the stomata 
during the experiment, owing to the 
action of this agent. Two leaves of 
HOURS 6 I 2 3 *• S 6 7 6 9 IO It 
Fig. 15. 
Cherry Laurel were therefore taken, and through the lamina of one numerous 
cuts were made pinnately with a sharp scalpel. Respiration readings were 
then taken for both leaves separately, chloroform being subsequently given 
to each at a concentration of o-i c.c. per litre of air-current. If the stomata 
closed owing to the action of the chloroform, it is to be expected that there 
would be less C 0 2 given out from the whole leaf than from the cut leaf. 
This was not found to be the case. The slight extra rise seen in the 
broken curve for the cut leaf, Fig. 16, was no doubt due to a slight increase 
