Chap. IX.] SUMMARY OP THE CHAPTER. 185 



rapid inflection, others have no such power; those which I 

 tried were all poisonous. 



Diluted alcohol (one part to seven of water) is not poison- 

 ous, does not induce inflection, nor increase the sensitiveness 

 of the glands to mechanical irritation. The vapour acts as 

 a narcotic or anajsthetic, 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 stomata of Drosera. They 

 sometimes excite extraordinarily rapid inflection, but this is 

 not an invariable result. If allowed to act for even a moder- 

 ately long time, they kill the leaves; whilst a small dose act- 

 ing for only a short time serves as a narcotic or anaesthetic. 

 In this case the tentacles, whether or not they have become 

 inflected, are not excited to further movement by bits of 

 meat placed on the glands, until some considerable time has 

 elapsed. It is generally believed that with animals and 

 plants these vapours act by arresting oxidation. 



Exposure to carbonic acid for 2 hrs,, and in one case for 

 only 45 m., likewise rendered the glands insensible for a 

 time to the powerful stimulus of raw meat. The leaves, 

 however, recovered their full powers, and did not seem in 

 the least injured, on being left in the air for 24 or 48 hrs. 

 We have seen in the third chapter that the process of 

 aggregation in leaves subjected for two hours to this gas and 

 then immersed in a solution of the carbonate of ammonia is 

 much retarded, so that a considerable time elapses before the 

 protoplasm in the lower cells of the tentacles becomes aggre- 

 gated. In some cases, soon after the leaves were removed 

 from the gas and brought into the air, the tentacles moved 

 spontaneously; this being due, I presume, to the excitement 

 from the access of oxygen. These inflected tentacles, how- 

 ever, could not be excited for some time afterwards to any 

 further movement by their glands being stimulated. With 



