upon Respiration and Assimilation. 1079 
were taken. Unless otherwise stated, each C0 2 -estimation represents a 
reading lasting two hours. 
Very small doses of chloroform may have no visible effect upon Barley 
leaves, but moderate and strong doses bring on two obvious changes : one, 
a change in the leaf-colour so that the bright green becomes a dull grey 
green, and the other an exudation of drops of water through the stomata 
on to the surfaces of the leaf. As a result of this loss of water from the 
mesophyll cells the leaf-blade becomes more or less flaccid. 
Experiment /. Chloroform dose , o-i c.c. Two separate lots of 15 grms. 
of Barley-shoots were observed simultaneously, one of them, the lower curve 
in Fig. 1, serving as the control. As regards the other one, the upper 
curve, after the preliminary, a single reading was taken to get the normal 
respiration value before chloroform was administered ; this was found to be 
hoursO 2 ^ 6 Q SO 12 14- 16 SB 
Fig. i. 
0-0023 grm. C 0 2 per hour. ^ The dose of chloroform was run in at the 
beginning of the second reading ; such a small quantity would be vaporized 
at once at 25 0 C. The second reading gave 0-0029 g rm - C 0 2 , showing 
a clear rise in the respiration, and this was followed by a gradual fall to 
0-0017 grm. This small dose of chloroform does not cause a visible 
change in the bright green colour of the leaves, but it brings about 
exudation of water so that the surface is covered with minute drops and the 
leaf becomes flaccid. Upon comparison with the normal curve of the control 
leaves it is seen that the respiration of the chloroformed leaves never falls 
below the normal output throughout the experiment. The effect of this 
small dose of chloroform was therefore to increase the C 0 2 -production 
by a temporary augmentation, after which the production declined to about 
normal. On p. 1083, where the effects of different doses are compared, this 
type of effect is represented in the schema as B (see Fig. 7). 
