Ever since the publication of Darwin’s “Origin of Species,” evolutionists have been divided into two sections where consciousness in the narrower sense is under discussion. The members of the one have contended that, though the physical and perhaps the lower mental nature of man is the outcome of evolutionary process, his higher mental attributes are of other origin. The members of the second section have urged that the higher not less than the lower characteristics of the mind of man have been evolved. It is somewhat strange that naturalists who accept the latter position are not infrequently impatient when any serious attempt is made to discuss it from the standpoint of psychology. It is, however, becoming more and more clearly evident that the discussion of the relation of the animal to the human mind, if it is to be made a subject of scientific inquiry, must be conducted on psychological lines by those who have devoted years of study to the subject. In this work such a discussion will be attempted, and animal behaviour will be treated as the precursor of human conduct, and as affording evidence of the germs from which the distinctively human mental attributes may have been evolved. CHAPTER III _INSTINCTIVE BEHAVIOUR_ I.--DEFINITION OF INSTINCTIVE BEHAVIOUR There are probably few subjects which have afforded more material for wonder and pious admiration than the instinctive endowments of animals. “I look upon instinct,” wrote Addison in one of his graceful essays, “as upon the principle of gravitation in bodies, which is not to be explained by any known qualities inherent in the bodies themselves, nor from any laws of mechanism, but as an immediate impression from the first Mover and the Divine Energy acting in the creatures.”[21] In like manner Spence said: “We may call the instincts of animals those faculties implanted in them by the Creator, by which, independent of instruction, observation or experience, and without a knowledge of the end in view, they are all alike impelled to the performance of certain actions tending to the well-being of the individual and the preservation of the species.”[22] According to such views, instinct is an ultimate principle the natural genesis of which is beyond the pale of explanation. But similar views were, at the time these passages were written, held to apply, not only to animal behaviour, but also to animal structure. The development of the stag’s antler, or of the insect’s wing, was also regarded as “an immediate impression from the first Mover and the Divine Energy acting in the creatures.” This view, however, is, neither in the case of structure nor in the case of behaviour, that entertained by modern science. It is indeed an expression of opinion concerning the metaphysics of instinct. Leaving the question of ultimate origin precisely where it stood in the times of Addison and of Spence, modern science seeks to trace the natural