Preface ix 



through the great kindness of Messrs Sutton of Reading, 

 who have given me the privilege of watching such parts of 

 their, work in raising varieties as seemed especially in- 

 structive, with unrestricted access to their pedigree books. 

 From this I have derived much profit, and many hints 

 which have formed the starting point for fuller experiment. 

 My hearty thanks are due to them for this important 

 assistance. 



W. BATESON. 



GRANTCHESTER, CAMBRIDGE. 

 February ', 1909. 



Note to the third impression. 



In the past three years the progress of Mendelian 

 analysis has been very rapid, and certain chapters of this 

 book, especially those dealing with Coupling and Repulsion, 

 and with the Heredity of Sex, are in essential respects out 

 of date, Knowledge of these subjects is at present in a 

 transitional stage, and I have endeavoured in a series of 

 brief Appendixes to acquaint the reader with the nature 

 of the principal advances made, while awaiting an oppor- 

 tunity of rewriting the book. 



I am obliged to Professor Arnold Lang and to 

 Mr C. C. Hurst for calling my attention to errors, which, 

 with some others, have been corrected. 



W. B. 



November ; 1912. 



