<J 



1 8 CLIMBING AND [i860. 



the adhesive glands were held fast and embraced, he sus- 

 pected that the leaves were adapted to supply nitrogenous 

 food to the plant. He therefore tried the effect on the leaves 

 of various nitrogenous fluids — with results which, as far as 

 they went, verified his surmise. In September, i860, 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 mar- 

 vellous. You will laugh ; but it is, at present, my full belief 

 (after endless experiments) that they detect (and move in 

 consequence of) the 2sVo P ai *t °f a sm gle 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 ! I began this work on Drosera in 

 relation to gradation as throwing light on Dionaea." 



Later in the autumn he was again obliged to leave home 

 for Eastbourne, where he continued his work on Drosera. 

 The work was so new to him that he found himself in diffi- 

 culties in the preparation of solutions, and became puzzled 

 over fluid and solid ounces, &c. &c. To a friend, the late 

 Mr. E. Cresy, who came to his help in the matter of weights 

 and measures, he wrote giving an account of the experiments. 

 The extract (November 2, i860) which follows illustrates 

 the almost superstitious precautions he often applied to his 

 researches : — 



" Generally I have scrutinised every gland and hair on the 

 leaf before experimenting ; but it occurred to me that I might 

 in some way affect the leaf ; though this is almost impossible, 

 as I scrutinised with equal care those that I put into distilled 

 water (the same water being used for dissolving the carbonate 

 of ammonia). I then cut off four leaves (not touching them 

 with my fingers), and put them in plain water, and four other 

 leaves into the weak solution, and after leaving them for an 

 hour and a half, I examined every hair on all eight leaves ; 



