CONTENTS 



CHAPTER I 



The Problem 



PAGE 

 I 



CHAPTER H 

 Historical 7 



CHAPTER HI 

 Mendel's Work . . .... 15 



CHAPTER IV 



The Presence and Absence Theory . .26 



CHAPTER V 



Interaction of Factors 39 



CHAPTER VI 



Reversion ........ '54 



vii 



