AMEBOID MOVEMENT AMEBOID MOVEMENT BY ASA A. SCHAEFFER, PH.D. PROFESSOR OF ZOOLOGY, UNIVERSITY OF TENNESSEE PRINCETON UNIVERSITY PRESS PRINCETON LONDON: HUMPHREY MILFORD OXFORD UNIVERSITY PRESS 1920 Copyright, 1920, by PRINCETON UNIVERSITY PRESS Published 1920 Printed in the United States of America [Illustration] PREFACE Although the subject of ameboid movement is discussed in this book chiefly because of its intrinsic interest, yet the interests of the student of medicine, the psychologist, the physiologist, the evolutionist and the general biologist have constantly been kept in mind. For the medical investigator probably finds no better means of approach to the study of the reactions and especially the movements of the white blood corpuscles, which play such an important part in the economy of the human body, than the ameba; white blood corpuscles and amebas are strikingly similar in many characteristics and in the fundamental processes of the movement they are probably identical. The comparative psychologist is keenly interested in the activities of the ameba because it exhibits to him the operation of the animal mind in its greatest simplicity. To the physiologist ameboid movement has for a long time represented the simplest phase of muscular contraction as it is known in the vertebrates. The philosophical evolutionist sees in the ameba, both in its structure and in its activities, a close approximation to the earliest ancestor of the animals. And the general biologist, aside from his usual interest in the properties of living matter wherever it may be found, is especially interested in discovering how many of the activities of the ameba are common to other organisms.