vi CONTENTS 



PAGZ 



XIX. THE CURVE OF LIFE . . .142 



XX. REJUVENESCENCE . . .150 



XXI. THE BIOLOGY OF TWINS . .158 



XXII. A LIMB FOR A LIFE . . . 166 



XXIII. LATENT LIFE . . . . 175 



XXIV. THE STORING INSTINCT . . 183 

 XXV. THE ROVING IMPULSE . .191 



XXVI. THE PROBLEM OF PARASITISM . 198 



XXVII. WONDERS OF INSTINCT . . 206 



XXVIII. MAKING A HOME FOR LIFE . 213 



XXIX. WITH DARWIN FORWARDS . 221 



XXX. THE MENDELIAN CLUE . . 229 



XXXI. THE FOUNTAIN OF CHANGE . 238 



XXXII. PROBLEM OF CAVE BLINDNESS . 246 



XXXIII. CONVERGENCE IN EVOLUTION . 254 



XXXIV. DOES ACQUIRED VIGOR COUNT? 263 

 XXXV. THE UNSEEN GOAL ... 270 



XXXVI. BEFORE THE DAWN OF ART . 278 



XXXVII. MAN'S ARBOREAL APPRENTICE- 

 SHIP 287 



XXXVIII. SEQUEL TO " THE JUKES " . 294 



XXXIX. THE OPTIMISM OF PATHOLOGY 302 



XL. THE CULT OF JOY . . . 309 



