But though the importance of intelligent adjustment to the circumstances of life is widely admitted as a general principle, it is perhaps through a study of animal behaviour that we are best able to realize its full range and extent. Biologists are so largely, and quite wisely, occupied in the study of morphological and physiological problems, which admit of a treatment more exact than the most ardent advocate of the investigation of behaviour, under natural or even under experimental conditions, can claim; they devote, again quite rightly, so large a share of attention to the variation and natural selection of adaptive structure in its adult condition and embryonic stages; the pendulum of opinion has, under the teaching of Professor Weismann, swung so far in the direction of the non-acceptance of the hereditary transmission of characters individually acquired through intelligent adjustment or otherwise; that the part played by consciousness in the evolution of the higher and more active animals is apt to pass unnoticed or unrecorded. It is well, therefore, to put in a reminder that a great number of animals would never reach the adult state in which they pass into the hands of the comparative anatomist save for the acquisition of experience, and the effective use of the consciousness to which they are heirs; that their survival is due, not only to their possession of certain structures and organs, but, every whit as much, to the practical use to which these possessions are put in the give and take of active life; and that many interesting problems which are keenly discussed by evolutionists in the light of natural selection presuppose conscious situations which are more or less tacitly taken for granted. Let us cast a rapid glance over some of these topics of biological discussion. The fascinating subject of mimicry, involving as it necessarily does the discussion of the value of warning colours and behaviour, a subject opening up an extensive group of problems so brilliantly studied by Professor Poulton, is meaningless save in so far as there is implied a conscious reaction to colour and form on the part of animals which can learn from experience. The warning colours reinstate a conscious situation, so that, misled by appearances, a bird mistakes the mimicking insect for its nauseous “model.”