Page:Darwin - On the movements and habits of climbing plants.djvu/59

 out, following with accuracy every inequality of the surface. I then placed a post without bark, but much fissured, and the points of the tendrils crawled into all the crevices in a beautiful manner. To my surprise, I observed that the tips of immature tendrils, with the branches not yet fully separated, likewise crawled, just like roots, into the minutest crevices. In two or three days after the tips had thus crawled into the crevices, or after their hooked ends had seized some minute point, the final process, now to be described, commenced.

This process I discovered by having accidentally left a piece of wool near a tendril. I then bound a quantity of flax, moss, and wool (the wool must not be dyed, for these tendrils are excessively sensitive to some poisons) loosely round sticks, and placed them near tendrils. The hooked points soon caught the fibres, even loosely floating fibres, and now there was no recoiling; on the contrary, the excitement from the fibres caused the hooks to penetrate the fibrous matter and to curl inwards, so that each hook firmly caught one or two fibres, or a small bundle of them. The tips and the inner surfaces of the hooks now began to swell, and in two or three days could be seen to be visibly enlarged. After a few more days the hooks were converted into whitish, irregular balls, rather above the th of an inch in diameter, and formed of coarse cellular tissue, which sometimes wholly enveloped and concealed the hooks themselves. The surfaces of these balls secrete some viscid resinous matter, to which the fibres of the flax, &c. adhere. When a fibre has become fastened to the surface, the cellular tissue does not grow directly beneath it, but continues to grow closely on each side; so that when several adjoining fibres, though excessively thin, were caught, so many crests of cellular matter, each not as thick as a human hair, grew up between them, and these, arching over on both sides, grew firmly together. As the whole surface of the ball continues to grow, fresh fibres adhere and are enveloped; so that I have seen a little ball with between fifty and sixty fibres of flax crossing at various angles, all imbedded more or less deeply. Every gradation in the process could be seen—some fibres merely sticking to the surface, others lying in more or less deep furrows, or deeply imbedded, or passing through the very centre of the cellular ball. The imbedded fibres are so closely clasped that they cannot he withdrawn. The cellular outgrowth has such a tendency to unite, that two balls produced from two branches sometimes grow into a single one.