6 CONTENTS. 



PAGB 



In-and-in breeding: Used for fixing characters Evil 

 effects of. 



Prep o tency : Defined Males usually prepotent 

 Chamoise sheep. 



Growth. 



CHAPTER II. 

 THEORIES OF HEREDITY AND VARIATION 48 



Heredity is self-evident Variation demands explan- 

 ationVariation defined as applying to characters Con- 

 genital and acquired characters Variations existing at 

 birth are congenital. 



Assigned causes of congenital variation: Climate and 

 environment Ancestral use and disuse Unlike parents- 

 Views of Aristotle Inherited mutilations Lamarck's 

 laws. 



Weismann's theory: Cells Multiplication of cells- 

 Conjunction of cells Germ cells and somatic cells Pro- 

 pagation by conjunction of cells Continuity of the germ 

 plasm Germ cells protected from exterior influences Neo- 

 Darwinians and neo-Lamarckians Conflict between their 

 theories Practical necessity of knowledge on the subject. 



CHAPTER III. 

 BASIS OF INVESTIGATION ,59 



The problem stated Non-functional characters Func- 

 tionally active organs Organs compared Effect of func- 

 tional activity Functional capacity Use-inheritance 

 means the inheritance of acquired functional capacity 

 The brain as a functional organ selected for investigation. 



Deduction from Weismann's theory: Law of proba- 

 bilities Extent of variation Relative fertility of classes 

 Result of different degrees of fertility Present condi- 

 tions show that the lower classes produce more rapidly than 



