CHAP. IX. SUMMARY OF THE CHAPTER. 227 



The action of camphor dissolved in watei 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 

 2 m. 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 anaesthetic, and long 

 exposure to it kills the leaves. 



The vapours of chloroform, sulphuric 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- 

 inata 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 short time serves as a narcotic or anaesthetic. 

 In this case the tentacles, whether or not they have 



