700 Thoday . — On the Effect of Chloroform on 
quotient when these are small. When a number of leaves are packed 
together in a small space it is difficult to ensure the uniform distribution 
of the gases before withdrawing a sample for analysis ; and also during 
a period of several hours’ enclosure the large increase in the concentration of 
carbon dioxide which takes place results in a storage of carbon dioxide in 
the tissues ready to reappear as an apparent acceleration of the respiration 
as soon as the air has been renovated. Modifications are in progress by 
which it is hoped to push the investigation further. 
Experiments with Cherry Laurel. 
Six leaves were enclosed together in the respiration chamber for each 
experiment. Before treatment with chloroform, determinations of the 
normal rate of respiration were made. 
The results are given, usually in graphic form, in cubic centimetres of 
oxygen or C 0 2 per hour per leaf. The continuous line gives the rate 
of absorption of oxygen, the broken line the rate of production of C 0 2 . 
All the experiments were carried out at the temperature prevailing in 
the laboratory. 
The experiments first given show the effect of exposure to the vapour 
of chloroform in relatively low concentration, which produced no visible 
change in the leaves. 
Experiment I. July 14, 1911. Dose, 0-2 c.c. liquid chloroform per 
litre of air for 15 minutes. Fresh Cherry Laurel leaves. 
Six leaves of the current season, weighing n*o grammes, were gathered 
Fig. 2. 
the previous evening after a bright sunny day, and left in the dark with 
their stalks in water under an inverted beaker. Next morning they were 
enclosed for three hours to determine their normal rate of respiration, and 
then chloroformed. The rates of absorption of oxygen and evolution of 
C 0 2 per hour per leaf are shown graphically in Fig. 2. The temperature 
rose gradually from 19*4° C. at the beginning of the preliminary three hours 
to 22*8° C., nine hours after the chloroforming. 
