TABLE OF CONTENTS 21 



PAGE 



Individual selection and interspecific selection. — 

 The origin of mutations. — Partisans and opponents 

 of the mutation theory. — Its practical importance. 



CHAPTER XXI 



Resume 326 



The present status of the question. — Differentia- 

 tion and adaptation. — Theories of differentiation : 

 Mutation, orthogenesis, isolation. — Theories of 

 adaptation : Darwinism and Lamarckism. — Natural 

 selection, transmission of acquired characters. — 

 The limits of adaptation. — Structure and func- 

 tion. — Non-adaptive variations. — Increasing com- 

 plexity of living things. — A possible solution of 

 the question at issue. 



Conclusion . . . .... . i., ... i.. . 338 



