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 Oven[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 Vertebræ 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]