Bird Migration from the Standpoint of Its Periodic Accuracy

ON• must confess to a feeling of trepidation on entering into such a dangerous field of discussion as bird migration, especially in its theoretical aspect, for perhaps no scientific subject has been so flooded with wild speculation, dogmatic assertions and poetical fancy.This is natural, because the facts cannot fail to come to the notice of every lover of nature, and their msthetie quality makes them attractive material for thought and discussion.Bird migration touches many interesting provinces of science, such as zo6geography, geology, meteorology, evolution and comparative psychology.What has recently excited the writer's curiosity is the meaning of the time sense of certain species of birds, especially where such an accurate sense does not seem to be warranted; in a word, where it seems more highly developed than is compatible with adaptive necessity.In the past decade many of the facts of migration have become common knowledge, but when these facts are completely grasped, and even when the movements of the individual bird have been thoroughly studied, the great problem of migration is likely to remain as much unsolved as ever, for the sense on which distant orientation depends, and the instinet whleh starts the travellers are beyond the reach of our present methods of investigation.Instinet itself is of course the fundamental problem, a problem as deep and obscure as any in the realm of philosophy.Bergson says: "The intellect is characterized by a natural inability to comprehend life.Inst]nct on the contrary is moulded on the very •orm of life.While intelligence treats everything mechanically, instinct proceeds so to speak organically.If the consciousness that slumbers in it should awake, if it were wound up into knowledge, instead of being wound off into action, if we could ask and it could reply, it would give up to us the most intimate secrets of life."• Bergson, Creative Evohltion, p. 165.