Chapter I: Preface

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.

The first is associated with the great names of Aristotle, Cuvier, and von Baer, and leads easily to the more open vitalism of Lamarck and Samuel Butler. The typical representative of the second attitude is E. Geoffroy St. Hilaire, and this habit of thought has greatly influenced the development of evolutionary morphology.

The main battle-ground of these two opposing tendencies is the problem of the relation of function to form. Is function the mechanical result of form, or is form merely the manifestation of function or activity? What is the essence of life--organisation or activity?

The materialistic attitude is not distinctively biological, but is common to practically all fields of thought. It dates back to the Greek atomists, and the triumph of mechanical science in the 19th century has induced many to accept materialism as the only possible scientific method. In biology it is more akin to the formal than to the functional attitude.

In the course of this book I have not hidden my own sympathy with the functional attitude. It appears to me probable that more insight will be gained into the real nature of life and organisation by concentrating on the active response of the animal, as manifested both in behaviour and in morphogenesis, particularly in the post-embryonic stages, than by giving attention exclusively to the historical aspect of structure, as is the custom of "pure morphology." I believe we shall only make progress in this direction if we frankly adopt the simple everyday conception of living things--which many of us have had drilled out of us--that they are active, purposeful agents, not mere complicated aggregations of protein and other substances. Such an attitude is probably quite as sound philosophically as the opposing one, but I have not in this place attempted any justification of it. I have touched very lightly upon the controversy between vitalism and materialism which has been revived with the early years of the present century. It hardly lends itself as yet to historical treatment, and I could hardly hope to maintain with regard to it that objective attitude which should characterise the historian.

The main result I hope to have achieved with this book is the demonstration, tentative and incomplete as it is, of the essential continuity of animal morphology from the days of Aristotle down to our own time. It is unfortunately true that modern biology, perhaps in consequence of the great advances it has made in certain directions, has to a considerable extent lost its historical consciousness, and if this book helps in any degree to counteract this tendency so far as animal morphology is concerned, it will have served its purpose.

I owe a debt of gratitude to my friends Dr James F. Gemmill and Prof. J. Arthur Thomson for much kindly encouragement and helpful criticism. The credit for the illustrations is due to my wife, Mrs Jehanne A. Russell. One is from Nature; the others are drawn from the original figures.

E.S.R.

CHELSEA, 1916.

CONTENTS

CHAP. PAGE

I. THE BEGINNINGS OF COMPARATIVE ANATOMY 1

II. COMPARATIVE ANATOMY BEFORE CUVIER 17

III. CUVIER 31

IV. GOETHE 45

V. ETIENNE GEOFFROY ST HILAIRE 52

VI. THE FOLLOWERS OF ETIENNE GEOFFROY ST HILAIRE 79

VII. THE GERMAN TRANSCENDENTALISTS 89

VIII. TRANSCENDENTAL ANATOMY IN ENGLAND--RICHARD OWEN 102

IX. KARL ERNST VON BAER 113

X. THE EMBRYOLOGICAL CRITERION 133

XI. THE CELL-THEORY 169

XII. THE CLOSE OF THE PRE-EVOLUTIONARY PERIOD 190

XIII. THE RELATION OF LAMARCK AND DARWIN TO MORPHOLOGY 213

XIV. ERNST HAECKEL AND CARL GEGENBAUR 246

XV. EARLY THEORIES ON THE ORIGIN OF VERTEBRATES 268

XVI. THE GERM-LAYERS AND EVOLUTION 288

XVII. THE ORGANISM AS AN HISTORICAL BEING 302

XVIII. THE BEGINNINGS OF CAUSAL MORPHOLOGY 314

XIX. SAMUEL BUTLER AND THE MEMORY THEORIES OF HEREDITY 335

XX. THE CLASSICAL TRADITION IN MODERN MORPHOLOGY 345

INDEX 365

ILLUSTRATIONS

FIG. PAGE

1. HYOID ARCH OF THE CONGER. (ORIGINAL.) 58

2. "VERTEBRA" OF A PLEURONECTID. (GEOFFROY.) 61

3. ABDOMINAL SEGMENT OF THE LOBSTER. (GEOFFROY.) 63

4. IDEAL TYPICAL VERTEBRA. (OWEN.) 102

5. NATURAL TYPICAL VERTEBRA. (OWEN.) 103

6. THE ARCHETYPE OF THE VERTEBRATE SKELETON. (OWEN.) 105

7. IDEAL TRANSVERSE SECTION OF A VERTEBRATE EMBRYO.
(VON BAER.) 119

8. GILL-SLITS OF THE PIG EMBRYO. (RATHKE.) 134

9. MECKEL'S CARTILAGE AND EAR-OSSICLES IN EMBRYO OF
PIG. (REICHERT.) 145

10. CRANIAL VERTEBRAE AND VISCERAL ARCHES IN EMBRYO
OF PIG. (REICHERT.) 148

11. EMBRYONIC CRANIUM OF THE ADDER. (RATHKE.) 152

12. TRANSVERSE SECTION OF CHICK EMBRYO. (REMAK.) 211

13. DEVELOPMENT OF THE ASCIDIAN LARVA (KOWALEVSKY.) 272

14. TRANSVERSE SECTION OF THE WORM _NAIS_. (SEMPER.) 280

15. THE FIVE PRIMARY STAGES OF ONTOGENY. (HAECKEL.) 292

FORM AND FUNCTION