2 CONTENTS. 



PART II. 



I. THE DARWINIAN THEORY OF ORGANIC EVOLU- 

 TION . .... 71 



II. RACE 74 



III. SIMILARITY OF SUCCESSIVE TYPES ... 81 

 IV. THE STRUGGLE FOR EXISTENCE AND NATURAL 



SELECTION 85 



V. THE ACCUMULATION OF BENEFICIAL DIFFER- 

 ENCES ....... 92 



VI. THE TIME ELEMENT ..... 98 



VII. RETROGRESSION 102 



VIII. VARIATION ...... 107 



VARIETY OF EXPRESSION . . . 108 



ACCIDENTAL (1 SPONTANEOUS) VARIATION 110 

 SPECIFIC VARIATION . . . .113 



ix. DARWIN'S EXAMPLES OF SPECIFIC VARIATION . 123 



X. USE OR DISUSE OF PARTS AND ADAPTATIONS 



OF ORGANS ...... 129 



XI. EXTERNAL INFLUENCES .... 135 



XII. INSTINCT AND HABIT 143 



XIII. DOMESTIC ANIMALS 150 



XIV. NATURAL SELECTION OF SPECIES . . . 160 



XV. GENERAL SUMMARY ..... 165 

 XVI. CONCLUSION . . . . .170 



