=Variation=, or differences between organs and also between organisms, is one of the most significant facts in nature. SUGGESTIONS.—The first fact that the pupil should acquire about plants is that no two are alike. The way to apprehend this great fact is to see a plant accurately and then to compare it with another plant of the same species or kind. In order to direct and concentrate the observation, it is well to set a certain number of attributes or marks or qualities to be looked for. =1.= Suppose any two or more plants of corn are compared in the following points, the pupil endeavouring to determine whether the parts exactly agree. See that the observation is close and accurate. Allow no guesswork. Instruct the pupil to measure the parts when size is involved. (1) Height of the plant. (2) Does it branch? How many secondary stems or “suckers” from one root? (3) Shade or colour. (4) How many leaves. (5) Arrangement of leaves on stem. (6) Measure length and breadth of six main leaves. (7) Number and position of ears; colour of silks. (8) Size of tassel, and number and size of its branches. (9) Stage of maturity or ripeness of plant. (10) Has the plant grown symmetrically, or has it been crowded by other plants or been obliged to struggle for light or room? (11) Note all unusual or interesting marks or features. (12) Always make note of comparative vigour of the plants. NOTE TO TEACHER.—The teacher should always insist on _personal work_ by the pupil. Every pupil should _handle and study the object by himself_. Books and pictures are merely guides and helps. So far as possible, study the plant or animal _just where it grows naturally_. =Notebooks.=—Insist that the pupils make full notes and preserve these notes in suitable books. Note-taking is a powerful aid in organizing the mental processes, and in insuring accuracy of observation and record. The pupil should draw what he sees, even though he is not expert with the pencil. The drawing should not be made for looks, but to aid the pupil in his orderly study of the object; it should be a means of self-expression. CHAPTER II THE STRUGGLE TO LIVE Every plant and animal is _exposed to unfavourable conditions_. It is obliged to contend with these conditions in order to live. No two plants or parts of plants are identically exposed to the conditions in which they live. The large branches in Fig. 1 probably had more room and a better exposure to light than the smaller ones. Probably no two of the leaves in Fig. 2 are equally exposed to light, or enjoy identical advantages in relation to the food that they receive from the tree. [Illustration: FIG. 3.—A BATTLE FOR LIFE.] Examine any tree to determine under what advantages or disadvantages any of the limbs may live. Examine similarly the different plants in a garden row (Fig. 3); or the different bushes in a thicket; or the different trees in a wood.