Contents 



XI 1 1 



CHAPTER X 



The Origin of the Different Kinds of Adaptations 

 Form and Symmetry 

 Mutual Adaptation of Colonial Forms 

 Degeneration ..... 

 Protective Coloration 

 Sexual Dimorphism and Trimorphism 

 Length of Life as an Adaptation 

 Organs of Extreme Perfection . 

 Secondary Sexual Organs as Adaptations 

 Individual Adjustments as Adaptations 

 Color Changes as Individual Adaptations 

 Increase of Organs through Use and Decrease throug 

 Reactions of the Organism to Poisons, etc. 

 Regeneration ...... 



CHAPTER XI 



Tropisms and Instincts as Adaptations 



382 



CHAPTER XII 



Sex as an Adaptation . 



The Different Kinds of Sexual Individuals 



The Determination of Sex 



Sex as a Phenomenon of Adaptation 



414 



4U 

 422 



439 



CHAPTER XIII 



Summary and General Conclusions 



452 



INDEX 465 



