different sciences, and the relative expense of equipment which the different sciences demand. Finally to be mentioned as a powerful factor is the recency of introduction of the various sciences to the course. All subjects shown in the high school course have entered it from above, having been handed down from the colleges, and tend to gravitate from the latter part of the course toward the earlier, until they find their supposed level in youthful capacity. Thus chemistry, the most recent introduction, has probably not yet exhausted its downward tendency.
Yet the foregoing influences are all more or less superficial and transient. Deeper than them all is a rational motive that has sometimes found its expression through them and should ultimately control the sequence of science in the high school.
With the young the learning process involves a great deal of muscular reaction. This necessity of motor expression diminishes with advancing years and the accumulation of an interpretive stock of motor experience with things. The size of the muscles involved in these reactions is an index of the stage of development of the learner. And since the accuracy and promptness of every muscle seem capable of unlimited improvement by education, they, too, indicate stages of development. On final analysis, the correct gradation and sequence of all rational school subjects will probably be found to conform to muscular development. The difficulties in high school sciences mostly inhere in the formulæ with which the teacher short-circuits his explanations or the verbiage with which he covers his ignorance. Whatever is definite is easy. Uncertain or confused things, only, are difficult and anything worth knowing may be taught the adolescent by a competent teacher.
Applying this test of motor adjustments, a solution of the problem of high school science will at the same time determine the correct sequence of the different phases of agriculture in the schools. All of the subjects involve the use of both the large and the small muscles. Subjects demanding more use of the finer muscles go later in the course than those involving more use of the coarser. Those requiring skill and accuracy of the larger muscles may often have an early or late treatment, or both. First-year high school students are familiar with or may make all of the adjustments demanded by such work as geography, soils, stream action, farm machines and elementary physics. Tillage, the study of the corn plant and ear, the morphology of root, stem and leaf, and budding, grafting, pruning and spraying involve motor adjustments appropriate to the grammar grades. The examination of cells, fibro-vascular bundles, and the stamens and pistils of most plants, and the making of biological drawings, work which exercises the finer muscles of accommodation, the preparation of slides and the
