342 BOTANY [Chap. XI 



Letter 666 straighten themselves again, and are again ready to catch. 

 So that the nervous system of Clematis feels only a prolonged 

 touch — that of Tropceolum a momentary touch : the peduncles 

 of the latter recover their original position, but Clematis, as 

 it comes into contact by growth with fixed objects, has no 

 occasion to recover its position, and cannot do so. You did 

 send me Flagellaria, but most unfortunately young plants do 

 not have tendrils, and I fear my plant will not get them for 

 another year, and this I much regret, as these leaf-tendrils 

 seem very curious, and in Gloriosa I could not make out the 

 action, but I have now a young plant of Gloriosa growing up 

 (as yet with simple leaves) which I hope to make out. Thank 

 Oliver for decisive answer about tendrils of vines. It is very 

 strange that tendrils formed of modified leaves and branches 

 should agree in all their four highly remarkable properties. 

 I can show a beautiful gradation by which leaves produce 

 tendrils, but how the axis passes into a tendril utterly puzzles 

 me. I would give a guinea if vine-tendrils could be found 

 to be leaves. 



It is an interesting fact that Darwin's work on climbing plants was 

 well advanced before he discovered the existence of the works of Palm, 

 Mohl, and Dutrochet on this subject. On March 22nd, 1864, he wrote 

 to Hooker : — " You quite overrate my tendril work, and there is no 

 occasion to plague myself about priority." In June he speaks of having 

 read " two German books, and all, I believe, that has been written on 

 climbers, and it has stirred me up to find that I have a good deal of new 

 matter." 



Letter 667 To J. D. Hooker. 



Down, June 2nd [1864]. 



You once offered me a Combretum} I having C. pur- 

 pureum, out of modesty like an ass refused. Can you now 

 send me a plant? I have a sudden access of furor about 

 climbers. Do you grow Adlumia cirr/iosa? Your seed did 

 not germinate with me. Could you have a seedling dug up 

 and potted? I want it fearfully, for it is a leaf-climber, and 

 therefore sacred. 



I have some hopes of getting Adlumia, for I used to grow 

 the plant, and seedlings have often come up, and we are now 



1 The two forms of shoot in C. argenteam are described in Climbing 

 Plants, p. 41. 



