You will find that those grown in the dark are very straggling and of a sickly yellowish colour, and are a great contrast to the shorter sturdier young green plants grown in the open air. The stems of those grown in the dark are long and limp, and not able to support themselves upright, while the distance between the leaves is very great, and the leaves themselves are small and useless (~see~ fig. 27). [Illustration: Fig. 27. Seedlings of Bean of the same age, A grown in the light, B in the dark.] Why should these plants have such a great length of stem? It shows us, that when the plant is already supplied with food, ~darkness does not prevent mere growth in length~. In fact it grows faster in ~length~ in the dark, which is an effort on the part of the plant to grow away from the darkness into the light. It economises in material and does not form stiff, thick stems and big leaves which would be useless until it reaches the light. If you now make a small chink in the black box with which you cover the plants, you will find that they grow towards it and through it into the light. Once the tip of the stem is outside in the light, it will form the usual leaves at the proper intervals from one another. The power of rapid growth in length of a plant growing in darkness, which economises the material generally used for strengthening the plant, and its power of growing towards the light, combine to be of practical use to a bulb or seed which is planted too deep in the earth. You will find that the part underground has much the same character as a plant grown in artificial darkness, until it reaches the surface. These weak underground stems bring the growing part into the light, and the plant does not waste material in forming large leaves and strong stems underground where they would be useless. Although light is so important, it does not follow that the stronger the light, the better it is for the plant; just as it does not follow that because we like to be warm, we like to be as hot as possible. It has been found that plants bend away from the light when it is too strong for them, as you may see in some plants near one of those very brilliant electric lamps. The sun even is sometimes too brilliant (English plants, however, do not suffer from that very much), and many plants living in the tropics and regions of strong sunlight, protect themselves from its direct rays by a number of different devices. CHAPTER IX. GROWTH IN SEEDLINGS When once the young plants start growing under suitable conditions they steadily get bigger. At first sight they appear to grow equally all over, stretching out in each direction as indiarubber does when it is pulled. Let us try to find out whether this is actually the case. [Illustration: Fig. 28. A Bean seedling: A, with divisions marked on root and stem; B, after further growth, showing where most of the stretching has taken place.]