1078 Irving .— The Effect of Chloroform 
carried out, it is always possible to see that the respiration remains ap¬ 
proximately uniform for a few hours, and then begins to fall off in a curve, 
at first quickly and afterwards slower, towards a small constant value. This 
holds for all the leaves employed ; therefore unless there is any actual need 
for mentioning the controls, which were often made, they will be omitted 
from the figures. 
It has been thought unnecessary to print full tables of all the actual 
estimations of C 0 2 , and so throughout the paper each experiment is repre¬ 
sented only by a graphic figure. 
In these figures the ordinates are grammes of C 0 2 actually given off per 
two hours, this being the usual duration of each single reading. These 
amounts are not reduced everywhere to a uniform weight of leaf, but they 
refer to a weight of fifteen grammes in the case of all Barley experiments, and 
to the variable weight of a single leaf in the case of Cherry Laurel. 
The abscissae are hours from the beginning of the experiment, and the 
hatching at the base of the figures indicates the time and duration of appli¬ 
cation of the chloroform vapour. In Part II, where the leaves are some¬ 
times in the light sometimes in the dark, this is indicated by the white or 
black band along the top of the figure. 
PART I. SECTION I. 
The Effect of Single Doses of Chloroform on Respiration. 
For all the experiments in this section young shoots of Barley were 
employed. 
The Barley was grown in pots under similar conditions and cut off just 
above the surface of the ground when the shoots were six inches tall. 
Enough shoots to weigh just 15 grms. were collected for each experiment, 
so that the C 0 2 -numbers are directly comparable in this section. 
The cut shoots were weighed and at once placed in the leaf-chamber, 
which, after being sealed, was in its turn placed in the water-bath already 
at the temperature of 25 0 C. The leaf-chamber itself was a tall glass jar of 
about 970 c.c. in volume, and square in section, with a glass lid which was 
waxed on at the beginning of each experiment; through this lid passed 
the air-inlet tube, which almost reached the bottom of the chamber, and 
the short exit tube. The Barley leaves were arranged to stand round the 
sides of the chamber, in water about J inch deep. At a certain time after 
the beginning of the experiment the dose of chloroform was run in from 
a fine pipette through the inlet tube into a small open dish standing in the 
middle of the bottom of the chamber, from which it readily vaporized. 
At the beginning of every experiment the air-current was allowed to 
run for a preliminary 2-3 hours before any actual estimations of C 0 2 
