Do not read this till you have leisure. If that blessed moment ever comes, I should be very glad to have your opinion on the subject of this letter. I am led to the opinion that Drosera must have diffused matter in organic connection, closely analogous to the nervous matter of animals. When the glans of one of the papillae or tentacles in its natural position is supplied with nitrogenized fluid and certain other stimulants, or when loaded with an extremely slight weight, or when struck several times with a needle, the pedicel bends near its base in under one minute. These varied stimulants are conveyed down the pedicel by some means; it cannot be vibration, for drops of fluid put on quite quietly cause the movement; it cannot be absorption of the fluid from cell to cell, for I can see the rate of absorption, which, though quick, is far slower, and in Dionaea the transmission is instantaneous; analogy from animals would point to transmission through nervous matter. Reflecting on the rapid power of absorption in the glans, the extreme sensibility of the whole organ, and the conspicuous movement caused by varied stimulants, I have tried a number of substances which are not caustic or corrosive, ... but most of which are known to have a remarkable action on the nervous matter of animals. You will see the results in the inclosed paper. As the nervous matter of different animals is differently acted on by the same poisons, one would not expect the same action on plants and animals; only, if plants have diffused nervous matter, some degree of analogous action. And this is partially the case. Considering these experiments, together with the previously made remarks on the functions of the parts, I cannot avoid the conclusion that Drosera possesses matter at least in some degree analogous in constitution and function to nervous matter. Now do tell me what you think, as far as you can judge from my abstract. Of course many more experiments would have to be tried; but in former years I tried on the whole leaf, instead of on separate glands, a number of innocuous substances, such as sugar, gum, starch, etc., and they produced no effect. Your opinion will aid me in deciding some future year in going on with this subject. I should not have thought it worth attempting, but I had nothing on earth to do. My dear Hooker, yours very sincerely, CH. DARWIN. P.S.--We return home on Monday 28th. Thank Heaven! THE STRUGGLE FOR EXISTENCE From the 'Origin of Species'