Cuap. IX SUMMARY OF THE CHAPTER. 227 
The action of camphor dissolved in water is remark- 
able, for it not only soon induces inflection, but 
apparently renders the glands extremely sensitive to 
mechanical irritation ; for if they are brushed with a 
soft brush, after being immersed in the solution for 
a short time, the tentacles begin to bend in about 
2m. It may, however, be that the brushing, 
though not a sufficient stimulus by itself, tends to 
excite movement merely by reinforcing the direct 
action of the camphor. The vapour of camphor, on 
the other hand, serves as a narcotic. 
Some essential oils, both in solution and in vapour, 
cause rapid inflection, others have no such power; 
those which I tried were all poisonous. 
Diluted alcohol (one part to seven of water) is not 
poisonous, does not induce inflection, nor increase the 
sensitiveness of the glands to mechanical irritation. 
The vapour acts as a narcotic or anesthetic, and long 
exposure to it kills the leaves. 
The vapours of chloroform, sulphurie and nitric 
ether, act in a singularly variable manner on different 
leaves, and on the several tentacles of the same leaf. 
This, I suppose, is owing to differences in the age or 
constitution of the leaves, and to whether certain 
tentacles have lately been in action. That these 
vapours are absorbed by the glands is shown by their 
changed colour; but as other plants not furnished 
with glands are affected by these vapours, it is 
probable that they are likewise absorbed by the sto- 
mata of Drosera. They sometimes excite extraordi- 
narily rapid inflection, but this is not an invariable 
result. If allowed to act for even a moderately long 
time, they kill the leaves; whilst a small dose acting 
for only a shoré time serves as a narcotic or anesthetic. 
In this case the tentacles, whether or not they have 
