Fig. 1.—No Two Branches are Alike. (Hemlock.)
If one compares any two plants of the same kind ever so closely, it will be found that they differ from each other. The difference is apparent in size, form, color, mode of branching, number of leaves, number of flowers, vigor, season of maturity, and the like; or, in other words, all plants and animals vary from an assumed or standard type.
If one compares any two branches or twigs on a tree, it will be found that they differ in size, age, form, vigor, and in other ways (Fig. 1).
If one compares any two leaves, it will be found that they are unlike in size, shape, color, veining, hairiness, markings, cut of the margins, or other small features. In some cases (as in Fig. 2) the differences are so great as to be readily seen in a small black-and-white drawing.
Fig. 2.—No Two Leaves are Alike.
If the pupil extends his observation to animals, he will still find the same truth; for probably no two living objects are exact duplicates. If any person finds two objects that he thinks to be exactly alike, let him set to work to discover the differences, remembering that nothing in nature is so small or apparently trivial as to be overlooked.
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 endeavoring 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 color.
(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; color 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 vigor 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.
Laboratory.—Every school, however small, should have a laboratory or work-room. This work-room may be nothing more than a table at one side of the room where the light is good. Here the specimens may be ranged and studied. Often an aquarium and terrarium may be added. A cabinet or set of shelves should be provided for a museum and collection.
The laboratory may be in part out of doors, as a school garden; or the garden may be at the pupil’s home, and yet be under the general direction of the teacher.