24 THE THIRD YEARBOOK 



minor center may be resolved yet into others, which have an 

 organizing influence within the whole. The rational study of a 

 landscape involves nothing but the study of the relations that exist 

 among its parts. 



The course of a stream is the dominating organizing influence in 

 a valley. But each slope, especially if the stream lies east and west, 

 will have an organizing individuality of its own. The writer 

 recalls two such slopes which supported the two species of a genus 

 of plants. Each species, however, was confined entirely to its own 

 particular hillside, though the valley was not more than a quarter 

 of a mile in width. 



Each slope will present in itself different centers of organization. 

 Even the casual observation of children will show that it is some- 

 thing more than accident that segregates the plants with the fine 

 capillary roots on the sandy crest, and that it is more than coinci- 

 dence that groups the thicker-fascicled roots in the alluvial bottoms. 



Even a single living tree becomes an interesting center for study. 

 It is beset by many things that without it could not possibly exist. 

 The green algae on one side and not on the other speak of the 

 contrasts of heat which it affords. The moss clustering at its base, 

 and ascending the stem in a thinner layer, accurately measures the 

 area of moisture furnished by its capillary bark ; while the papery 

 lichens take undisputed possession of the dryer areas above. Its 

 dried and riven bark furnishes protection for crowds of insects 

 that find shelter in the crevices, and these in their turn become the 

 chief attraction for a vigilant host of birds. Even when dead 

 and prostrate it is a center of no less activity. Beset by a new 

 race of animals and plants, it remains a determining influence upon 

 a considerable community until the last vestige is returned to the 

 original elements. Here again a broad presentation brings the pupil 

 at once face to face with nature at work. He acquires some notion 

 of the dynamism in creation, which is the beginning of wisdom. 



3. The landscape as a composite whole presents several series 

 of aspects, each of which includes a well-defined succession of events. 

 — These may be described as : 



a) The transitory and somewhat irregular changes ; as, for 

 example, those caused by the movement of a cloud over the sun, 

 the passing of a storm, the work of a flood, etc. 



