An easy and effective way to begin the study of the plant is to watch it as it sprouts from the seed. Since a large seed, easy to see and simple in structure, is best, an ordinary bean answers the purpose admirably, particularly as the bean has the convenient habit of rising up above the ground when it sprouts, the development of the embryo proceeding in full view. Any of the common varieties will answer the purpose, though of course the larger the bean the more easily it can be observed.
A child of three or four will be interested in watching a seed grow. The first season he may get only one idea, the seed grows into a plant. The next season the experiment may be repeated with as much of the story of the plant added as the little one can understand. Thus Spring after Spring the child plants his seeds and watches them grow, constantly adding to his store of knowledge about them, until the story of the plant and its seed is as familiar to him as any fairy-tale, and has gone into his consciousness to stay there forever. Let us examine the bean, then, and see what can be learned from it, the information thus obtained to be shared with the child as fast as his age and his power of understanding permit.
The Bean, Sprouting, To Show the Two Seed-leaves And The Embryo
First let us examine the dry bean. It is hard, so hard that we can scarcely bite it. Put it to soak in tepid water, leaving it over night. Next day look at the changes that have taken place in it. The first thing we notice is that it has swollen until it is twice as large as it was, being now soaked full of water. It is also softer than it was. Its outer skin during the process of soaking has loosened, being no longer firmly attached to the body of the bean. This skin, being unable to stretch, soon splits open by the swelling of the bean inside. We can easily slip it entirely off.
The Bean—Embryo-Leaves, Seed-Leaves, and Root
Having done this let us take a good look at the bean that is now out of its skin. We see that it is composed of two thick parts which are joined together at only one end. These two thick parts which make the bulk of the bean are called seed-leaves (cotyledons).
Just at the point where they seem to be joined together there is a tiny flat white object. Looking closely at this we discover it to be a plant consisting of two minute leaves and a little blunt tip. As a matter of fact, the two seed-leaves are not attached directly to each other, but each is attached to this tiny plant, or embryo, as it is called. The word "embryo" is a valuable one to use later, and its precise meaning can easily be fixed by always calling the young plant tucked away in the seed the embryo. The difficulty of learning new words does not lie in their length, but in not knowing what they mean. A child who has been to the circus has no trouble in remembering the word "elephant," and the child who frequently hears the word "embryo" spoken in connection with the plant concealed between the cotyledons quickly and unconsciously learns it.
Place some of the soaked beans on damp cotton, and plant others in a pot of earth, or, if it is Summer, in the garden. Those sprouted in the house in the Winter must be kept warm. In a short time the little white embryo tucked away in the bean begins to grow. We say the bean sprouts. As the embryo develops, its little blunt tip grows down into the ground and gives off roots. At the same time its two tiny white leaves grow large and green, coming out from the seed-leaves (cotyledons) into the air and sunshine. As the stem lengthens the seed-leaves are lifted up above the ground along with the embryo. The bean thus seems to come out of the ground, and children are very apt to want to cover it up. But it has not really unplanted itself. The lower part of the stem and the roots hold it firmly in the earth.