PREFACE TO THE FIRST EDITION ix 
the science of genetics of the more modest dimensions 
which I had contemplated. I should wish, however, 
particularly to recommend Dr. Lotsy’s lectures to any 
reader who wishes to go further into these matters. 
I am indebted to several friends for assistance during 
the course of my work. Mr. R. P. Gregory kindly 
read through the proof of the chapter on cytology ; and 
I wish here to record my thanks to Mr. J. Stanley 
Gardiner, to Mr. C. T. Regan, to Mr. W. S. Perrin, and 
to Mr. R. C. Punnett for information on special points. 
To the last-named I owe the photograph which appears 
as Fig. 15. I am particularly grateful to Mr. R. H. 
Biffen and to Mr. G. Udny Yule for access to work 
which has not hitherto appeared in print. 
Adequately to acknowledge Mr. Bateson’s influence 
upon these pages is a more difficult matter, and not 
the less so because I have deliberately refrained as 
far as possible from consulting him whilst the book 
was in course of preparation, in order that it might 
retain if possible some traces of individuality. It is 
therefore clear that he is in no way responsible for its 
deficiencies. But, apart from the fact that I am 
conscious of having quoted his ideas at more points 
than could possibly be acknowledged seriatim, I owe 
to Mr. Bateson both my first introduction to the science 
of genetics, and a continual fund of encouragement in 
the prosecution of studies connected with it. 
I have to thank Mr. Francis Darwin for kind per- 
mission to reproduce a portrait of his father; Professor 
