“I have just told you that many plants have only one cotyledon. I will add that this cotyledon is usually very small. It is especially in these plants that the perisperm is present. The grain of wheat offers [[157]]a notable illustration of this truth. Cut lengthwise and looked at through a magnifying-glass, this seed would reveal to us what is represented in the picture I now show you. At the bottom and toward one side is the germ, forming but a very small part of the seed. At c is the single cotyledon, whence will come the first leaf, the seminal leaf. At e is the gemmule, which will furnish the next leaves. At the opposite end is a short nipple, the radicle, whence the root will spring. Now compare the tiny cotyledon of the wheat with the two voluminous ones of the almond. The latter, with their rich store of nourishment, will easily be able to feed the young plant until it has vigorous roots; but the cotyledon of the wheat, so poor and slender—can it nourish the young plant? Certainly not. Then the wheat germ must without fail have a storehouse of provisions. This storehouse is the perisperm (pr), a farinaceous mass constituting nearly the whole of the seed. This same perisperm, the first food of the wheat’s first shoot, is also the chief food of man; it is what, under the millstone, becomes flour, of which bread is made. But how can the farinaceous substance of the perisperm nourish the plant? A very simple experiment will show us. Put some wheat in a saucer and keep it slightly moist. In a short time the seed will germinate. As soon as the young sprouts show their green points [[158]]take one of the grains: you will find it softened all through. You can crush it between your fingers and squeeze out a white fluid, very sweet to the taste and much resembling some sort of milk. What has taken place ought not to be beyond your power to surmise from the account I gave you of the wonderful change starch may undergo. The perisperm of the wheat-grain consists chiefly of starch. During germination this accumulation of starch is converted into a sugary substance, into glucose in fact. Thence comes the sort of plant-milk with which the seed is now swollen. The germ is immersed in this sweet liquid; it imbibes it, soaks it up almost as a fine sponge would; and with the matter thus absorbed it augments its own substance, which lengthens into root, stem, and leaves. With what furnishes us bread the grain of wheat suckles the starting wheat-stalk.” [[159]]
CHAPTER XXXIII
CULTIVATED PLANTS
“Three modes of plant-propagation are in use among horticulturists, namely: layering, slipping, and grafting. To get an adequate notion of the great usefulness of these operations let us dwell for a moment on the origin of our cultivated plants.
“You perhaps imagine that from the beginning of time, in view of our need of food, the pear-tree was eager to bear large fruit, plump and juicy; that the potato, just to accommodate us, stuffed its big tubers with farinaceous matter; that the cabbage, in its desire to gratify us, conceived the idea of gathering those beautiful white leaves into a compact head. You imagine that wheat, pumpkins, carrots, grapes, beets, and no one knows what besides, possessed with a great interest in man, have always worked for him of their own accord. You think that our grapes of to-day are like those from which Noah extracted the juice that made him drunk; that wheat, ever since it appeared on the earth, has never failed to yield its annual harvest of grain; that the beet and the pumpkin had at the beginning of the world the plumpness that makes them prized by us now. You imagine, in short, that our food-plants came to us originally just as we have them now. Undeceive yourselves: [[160]]the wild plant is usually of very little nutritive value to man. His is still the task of so cultivating it as to derive advantage from its natural aptitudes by improving them.
“In its native country, on the mountains of Chile and Peru, the potato in its wild state is a poor diminutive tuber about as large as a hazel-nut. Man takes the worthless wild stock into his garden, plants it in rich soil, tends it, waters it; and behold, from year to year the potato thrives more and more, gaining in size and in nutritive properties, and finally becoming a farinaceous tuber as large as your two fists.
“On the sea-coasts, exposed to all the winds that blow, there grows a wild cabbage with a tall stalk and a few green leaves of bitter taste and rank odor. But beneath its rude exterior it may perhaps hide invaluable aptitudes. Apparently this suspicion occurred to him who first, so long ago that the record of it is lost, took the sea-coast cabbage under cultivation. The suspicion was well-founded. The wild cabbage has been improved by man’s incessant care: its stalk has become firmer and its leaves have multiplied, whitened, acquired tenderness, and massed themselves in a compact head, so that we have the crisp and succulent cabbage of to-day as the admirable result of this notable metamorphosis. There on the sea-coast rock was the first beginning of the excellent plant; here in our gardens is its present attainment. But what about its intermediate forms which, through the centuries, marked the gradual [[161]]development of the species to its present high state of perfection? Each of these forms was a step forward, and each had to be preserved, kept from degenerating, and made the subject of still further improvement. Who could tell the story of all the labor and pains it has taken to produce the cabbage-head as we now have it?
“And the wild pear-tree—are you acquainted with it? It is a frightful bramble-bush, all bristling with sharp thorns; and the pears themselves—a most repellent fruit, sure to choke you and set your teeth on edge—are very small, sour, hard, and full of grit that reminds one of gravel-stones. Surely he must have had an extraordinary inspiration who first pinned his faith on this crabbed specimen of underbrush and foresaw in the remote future the butter-pear on which we regale ourselves to-day.
“In the same way, by the painstaking culture of the primitive vine, whose grapes were no larger than our elderberries, man has, in the sweat of his brow, developed the luscious fruit of the modern vineyard. From some poor species of grass now forgotten he has also produced the wheat that to-day supplies us with bread. A few wretched herbs and shrubs, far from promising in appearance, he has cultivated and improved until they became the vegetables and fruit trees so prized by us at present. This old earth of ours, in order to make us work and thus fulfill the law of our existence, has behaved to us like a harsh stepmother. To the birds of the air she gives food in abundance, but to us she offers of her own free [[162]]will nothing but wild blackberries and sour sloes. But let us not complain, for the stern struggle with necessity is precisely what constitutes our grandeur.