CONTENTS 



Introduction 



I'AGE 



SECTION I 



THE NEWEST THEORIES CONCERNING EVOLUTION 8 



SECTION II 



THE ORGANIC GROWTH OF THE LIVING WORLD 20 



Fundamental Causes of the Manifold Variety of Organic Forms 22 



Eeproduction as Organic Growth . . . .2-1 



Individual Development as Organic Growth . 



Separation of the World of Organic Forms into Species — 

 Genepistasis ...... 



The Particular Causes which determme the Difference of the 

 Directions of Evolution, and which also contribute to 

 bring about the Division into Species . .32 



Sexual Combination — One-sided Inheritance . . .35 



Intermittent Evolution — Kolliker's Hypothesis . . ■i'> 



Constitutional Impregnation . . . • . ol 



Elaboration and Simplification in the Evolution of Species 



25 



27 



52 



