i868 i88i] DISPERSAL OF SEEDS 387 



To F. Hildebrand. Letter 707 



Down, Feb. Qth [1872]. 



Owing to other occupations I was able to read only 

 yesterday your paper on the dispersal of the seeds of Com- 

 positae. 1 Some of the facts which you mention are extremely 

 interesting. 



I write now to suggest as worthy of your examination the 

 curious adhesive filaments of mucus emitted by the achenia 

 of many Compositae, of which no doubt you are aware. My 

 attention was first called to the subject by the achenia of an 

 Australian Pumilio (P. argyrolepis), which I briefly described 

 in the Card. Chronicle, 1861, p. 5. As the threads of mucus 

 dry and contract they draw the seeds up into a vertical 

 position on the ground. It subsequently occurred to me that 

 if these seeds were to fall on the wet hairs of any quadruped 

 they would adhere firmly, and might be carried to any 

 distance. I was informed that Decaisne has written a paper 

 on these adhesive threads. What is the meaning of the 

 mucus so copiously emitted from the moistened seeds of 

 Iberis, and of at least some species of Linum ? Does the 

 mucus serve as a protection against their being devoured, or 

 as a means of attachment. 2 I have been prevented reading 

 your paper sooner by attempting to read Dr. Askenasy's 

 pamphlet, 3 but the German is too difficult for me to make it 

 all out. He seems to follow Nageli completely. I cannot but 

 think that both much underrate the utility of various parts of 

 plants ; and that they greatly underrate the unknown laws of 

 correlated growth, which leads to all sorts of modifications, 

 when some one structure or the whole plant is modified for 

 some particular object. 



1 " Ueber die Verbreitungsmittel der Compositenfriichte." Bot. 

 Zeitung, 1872, p. i. 



2 Various theories have been suggested, e.g., that the slime by 

 anchoring the seed to the soil facilitates the entrance of the radicle 

 into the soil : the slime has also been supposed to act as a temporary 

 water- store. See Klebs in Pfeffer's Untersuchungen aus dem Bot. Inst. 

 zu Tubingen, I., p. 581. 



3 E. Askenasy, Beitriige zur Kritik der Darwin 1 schen Lehre. Leipzig, 

 1872. 



