CONTENTS. 



PREFACE : 



PART I. INTRODUCTION. 



WHAT IS EVOLUTION? 



PART 11. THE EVOLUTION OF LIVING BEINGS. 



CHAPTER I. DEFINITIONS OF TERMS USED 



DO DIPLOID SPECIES VARY? 



SPECIES, LINNEONS, GENERA AND OTHER 

 „HIGHER GROUPS" AND EVOLUTION . . 



THE ORIGIN OF DIPLOID SPECIES 



THE PERPETUATION OF THE NEW SPECIES 

 HOW TO GET AT THE CONSTITUTION OF 



THE GAMETES 



HOW CAN GROUPS OF DIFFERENTI.Y CON- 

 STITUTED TYPES FORM A LINNEON, SI- 

 MULATING A SPECIES ? 



THE LIMITS OF LINNEONS 



THE CAUSE OF THE INCREASE OF „VARIA- 

 BILITY" under DOMESTICATION .... 



PROGRESSION IN EVOLUTION 



THE EVIDENCE FOR THE OCCURENCE OF 

 CROSSES BETWEEN INDIVIDUALS BE- 

 LONGING TO DIFFERENT LINNEONS IN 

 NATURE 



THE EFFECT OF CROSSING LINNEONS.. 



THE ORIGIN OF THE GREAT CLASSES. . . 



THE QUESTION OF RELATIONSHIP .-, 



THE QUESTION OF PHYLOGENY 



HOMOLOGOUS P^RTS AND RUDIMENTARY 

 ORGANS 



II. 

 III. 



IV. 



V. 



VI. 



VII. 



VIII. 

 IX. 



X. 

 XI. 



XII. 

 XIII. 



xrv. 



XV. 



XVI, 



PAGE 



VII 



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