WHY BABY PLANTS BACK INTO THE WORLD
Most plants back into the world out of the seed like that. Why? To protect their tender first leaves. Suppose you were taking some very valuable thing, easily injured—baby brother, say—through a swinging door and you had to use both hands to carry him. You wouldn't open the door by pushing that dear, little tender head of his against it, would you? You'd open it by backing through.
Mr. Darwin was a wonderful hand at that sort of thing—getting nature people to tell their stories. He was an inventor, like Mr. Edison; only, instead of inventing telephones for human beings to talk with, he invented ways of talking for nature people. You saw how he fixed it so that the earthworms could tell what they knew about geometry and botany. Well, in the case of the roots, what did he do one day but take a piece of glass, smoke it all over with lampblack—you'd have thought he was going to look at an eclipse—and then set it so that Mr. Root could use it as a kind of writing-desk. In a hitching, jerky sort of way roots turn round and round as they grow forward. In the ground, to be sure, a root can't move as freely nor as fast as it did out in the open and over this smooth glass, but it does turn, slowly, little by little. The very first change in a growing seed is the putting out of a tiny root, and from the first this root feels its way along, like one trying to find something in a dark room. Thus it searches out the most mellow soil and also any little cracks down which it can pass.
CHARLES DARWIN
The great naturalist.
"Here's a fine opening for a live young chap," we can imagine one of these roots saying when it comes to an empty earthworm's burrow or a vacancy left by some other little root that has decayed and gone away. Roots always help themselves, when they can, to ready-made openings, and it is this round-and-round motion that enables them to find these openings.
But even this isn't all. A root not only moves forward and bends down—so that it may always keep under cover and away from the light—but it has a kind of rocking motion, swinging back and forth, like a winding river between its banks, and for a somewhat similar reason.