Letter 707. To F. Hildebrand. Down, February 9th [1872].

Owing to other occupations I was able to read only yesterday your paper on the dispersal of the seeds of Compositae. (707/1. "Ueber die Verbreitungsmittel der Compositenfruchte." "Bot. Zeitung," 1872, page 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 "Gardeners’ Chronicle," 1861, page 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. (707/2. 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., page 581.) I have been prevented reading your paper sooner by attempting to read Dr. Askenasy’s pamphlet, but the German is too difficult for me to make it all out. (707/3. E. Askenasy, "Beitrage zur Kritik der Darwin’schen Lehre." Leipzig, 1872.) 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.