320 BOTANY. [Ch. XVIL 



by my copier: the subject amused me when I had nothing 

 to do." 



He has described in the Autobiography (p. 47), the general 

 nature of these early experiments. He noticed insects sticking 

 to the leaves, and finding that flies, &c, placed on the adhesive 

 glands, were held fast and embraced, he suspected that 

 the captured prey was digested and absorbed by the leaves. 

 He therefore tried the effect on the leaves of various nitro- 

 genous fluids — with results which, as far as they went, verified 

 his surmise. In September, 1860, he wrote to Dr. Gray : — 



" I have been infinitely amused by working at Drosera': the 

 movements are really curious ; and the manner in which the 

 leaves detect certain nitrogenous compounds is marvellous. 

 You will laugh ; but it is, at present, my full belief (after 

 endless experiments) that they detect (and move in con- 

 sequence of) the 2 /flo P ar * °f a single grain of nitrate of 

 ammonia ; but the muriate and sulphate of ammonia bother 

 their chemical skill, and they cannot make anything of the 

 nitrogen in these salts 1 " 



Later in the autumn he was again obliged to leave home for 

 Eastbourne, where he continued his work on Drosera. 



On his return home he wrote to Lyell (November 1860) : — 



" I will and must finish my Drosera MS., which will take 

 me a week, for, at the present moment, I care more about 

 Drosera than the origin of all the species in the world. But 

 I will not publish on Drosera till next year, for I am frightened 

 and astounded at my results. I declare it is a certain fact, 

 that one organ is so sensitive to touch, that a weight seventy- 

 eight-times less than that, viz., 10 1 00 of a grain, which will move 

 the best chemical balance, suffices to cause a conspicuous 

 movement. Is it not curious that a plant should be far more 

 sensitive to the touch than any nerve in the human body? 

 Yet I am perfectly sure that this is true. When I am on my 

 hobby-horse, I never can resist telling my friends how well 

 my hobby goes, so you must forgive the rider." 



The work was continued, as t /holiday task, at Bournemouth, 

 where he stayed during the autumn of 1862. 



A long break now ensued in his work on insectivorous plants, 

 and it was not till 1872 that the subject seriously occupied him 

 again. A passage in a letter to Dr. Asa Gray, written in 1863 

 or 1864, shows, however, that the question was not altogether 

 absent from his mind in the interim : — 



" Depend on it you are unjust on the merits of my beloved 

 Drosera ; it is a wonderful plant, or rather a most sagacious 

 animal. I will stick up for Drosera to the day of my death. 



