"THIS book is not intended to be a full or detailed history of animal morphology: a complete account is given neither of morphological discoveries nor of morphological theories. My aim has been rather to call attention to the existence of diverse typical attitudes to the problems of form, and to trace the interplay of the theories that have arisen out of them. The main currents of morphological thought are to my mind three-the functional or synthetic, the formal or transcendental, and the materialistic or disintegrative."