316 BOTANY. [Ch. XVil. 



conception of the unity of what has hitherto seemed a chaos of 

 unrelated phenomena will be sustained, time alone will show. 

 But no one can doubt the importance of what Mr. Darwin has 

 done, in showing that for the future the phenomena of plant 

 movement can and indeed must be studied from a single point 

 of view." 



The work was begun in the summer of 1877, after the publi- 

 cation of Different Forms of Flowers, and by the autumn his 

 enthusiasm for the subject was thoroughly established, and he 

 wrote to Mr Dyer : "lam all on fire at the work." At this 

 time he was studyiDg the movements of cotyledons, in which 

 the sleep of plants is to be observed in its simplest form ; in 

 the following spring he was trying to discover what useful 

 purpose these sleep-movements could serve, and wrote to Sir 

 Joseph Hooker (March 25th, 1878) :— 



" I think we have proved that the sleep of plants is to lessen the 

 injury to the leaves from radiation. This has interested me 

 much, and has cost us great labour, as it has been a problem 

 since the time of Linnaeus. But we have killed or badly 

 injured a multitude of plants. N.B. — Oxalis carnosa was most 

 valuable, but last night was killed." 



The book was published on November 6, 1880, and 1500 

 copies were disposed of at Mr. Murray's sale With regard to 

 it he wrote to Sir J. D. Hooker (November 23) : — 



" Your note has pleased me much — for I did not expect that 

 you would have had time to read any of it. Bead the last 

 chapter, and you will know the whole result, but without the 

 evidence. The case, however, of radicles bending after ex- 

 posure for an hour to geotropism, with their tips (or brains) 

 cut off is, I think worth your reading (bottom of p. 525) ; it 

 astounded me. But I will bother you no more about my book. 

 The sensitiveness of seedlings to light is marvellous." 



To another friend, Mr. Thiselton Dyer, he wrote (Novem- 

 ber 28, 1880) : 



" Very many thanks for your most kind note, but you think 

 too highly of our work, not but what this is very pleasant. . . . 

 Many of the Germans are very contemptuous about making 

 out the use of organs ; but they may sneer the souls out of 

 their bodies, and I for one shall think it the most interesting 

 part of Natural History. Indeed you are greatly mistaken if 

 you doubt for one moment on the very great value of your 

 constant and most kind assistance to us." 



The book was widely reviewed, and excited much interest 

 among the general public. The following letter refers to a 

 leading article in the Times, November 20, 1880 : — 



