CONTENTS 



PAGE 



Introduction ...... 1 



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 . . . .24 



Individual Development as Organic Growth . . .25 



Separation of the World of Organic Forms into Species — 



Genepistasis . . . . . .27 



The Particular Causes which determine 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 — Kulliker's Hypothesis . . 45 



Constitutional Impregnation . . . . .51 



Elaboration and Simplification in the Evolution of Species . 52 



