CONTENTS. 



PAGE 



I. THE PROBLEM STATED i 



II. THE STUDY OF BIOLOGY . 14 



III. THE CONSTITUTION OF THE ANIMAL AND PLANT KINGDOMS . 36 



IV. CONCERNING PROTOPLASM 61 



V. THE EVIDENCE FROM RUDIMENTARY ORGANS .... 80 



VI. THE EVIDENCE FROM THE TAILS, LIMBS, AND LUNGS OF ANIMALS 97 



VII. THE EVIDENCE FURNISHED BY THE SCIENCE OF LIKENESSES . 121 



VIII. THE EVIDENCE FROM MISSING LINKS ..... 143 



IX. THE EVIDENCE FROM DEVELOPMENT. i. THE EARLIER STAGES 



IN THE LlFE-HlSTORY OF ANIMALS 167 



X. THE EVIDENCE FROM DEVELOPMENT. 2. THE LIFE-HISTORIES 



OF STAR-FISHES AND CRUSTACEANS 191 



XI. THE EVIDENCE FROM DEVELOPMENT. 3. THE DEVELOPMENT 



OF MOLLUSCS, AMPHIBIANS, &c 220 



XII. THE EVIDENCE FROM THE LIFE-HISTORIES OF INSECTS . . 252 



XIII. THE EVIDENCE FROM THE CONSTITUTION OF COLONIAL OR 



COMPOUND ANIMALS . . . - . . . . . 273 



XIV. THE FERTILISATION OF FLOWERS 308 



XV. THE EVIDENCE FROM DEGENERATION 342 



XVI. GEOLOGY AND EVOLUTION 366 



INDEX 377 



