vi PREFACE 



interest connected with anthocyanin pigments. For we have now, on 

 the one hand, satisfactory methods for the isolation, analyses and 

 determination of the constitutional formulae of these pigments. On 

 the other hand, we have the Mendelian methods for determining the 

 laws of their inheritance. By a combination of the two methods, we 

 are within reasonable distance of being able to express some of the 

 phenomena of inheritance in terms of chemical composition and 

 structure. There can be little doubt that exact information of this 

 kind must be at least helpful for the true understanding of the vital 

 and important subject of Heredity. 



In the preparation of this book I gratefully acknowledge the help 

 afforded to me by many of my friends, and I am especially indebted 

 to Mrs E. A. Newell Arber for kindly correcting my proofs. 



To Professor Bateson, F.R.S., my sincerest thanks are due for the 

 great interest he has taken in much of my work which is included in 

 this volume, and for his many valuable suggestions and criticisms. 

 I wish also to record my thanks to Dr F. F. Blackman, F.R.S., for 

 criticisms and assistance with the manuscript. 



I regret that some of the most recent and important work on the 

 subject has not been altogether successfully incorporated in the book, 

 owing to the difficulty I have experienced in learning, at the earliest 

 opportunity, of the results obtained by scientists in other countries 

 during this and the preceding year. 



M. W. 



CAMBRIDGE, 

 May, 1916. 



