16 MISS A. BATESON AND MR. F. DARWIN ON THE EFFECT OF 
introduced and a glass cover placed over the vessel. In this 
way it was easy to observe that :— 
(1) Low percentages of ether cause acceleration in the curling 
up of the curved stalk. 
(2) The stimulation can be renewed by repeated additions of 
ether.. 
(3) When the amount of ether reaches about 3 per cent., the 
tissues are killed, and the stalk uncurls. 
3. The Effects of Chloroform. 
The pith was placed in damp air in the jar used for the ether 
work, and the auxanometer-lever was employed to measure the ` 
“ growth.” 
We expected to find that, like ether, chloroform would stimu- 
late the “growth ” of the pith, since Elfving has found that 
both these substances stimulate respiration. This, however, was 
not the case*. In only one experiment did chloroform (about 
1'4 per cent.) have any stimulating effect on the “ growth” of 
the pith. 
. In some cases we found chloroform produce retardation. It is 
of course difficult to make sure of this result; but when, as in 
Experiment 17, the fall in the rate of growth is great and sudden, 
it must be attributed to the effect of chloroform. 
The following Table gives some of the results of experiments 
which are given in detail below :— 
Strength. Effect. 
0-008 per cent. ............ Retardation of “ growth.” 
0:05 » ees No effect. 
0:07 » 0I No effect. 
01 » 0 eem No effect. 
0:9 » ree Slow contraction. 
1:0 Do oe Slow contraction. 
Higher percentages also caused contraction. 
* Ether and chloroform act differently on the respiration of Willow-leaves, 
inasmuch as the optimum for ether lies between 3 and 7-9 per cent. ; while for 
chloroform it lies between 1-8 and 3 per cent. 
