PREFACE 



This book is intended as an introduction to the study of 

 heredity, which every one admits to be a subject of fascinating 

 interest and of great practical importance. In recent years 

 much progress has been made in the scientific study of heredity, 

 and, as the hterature is widely scattered, and often very technical, 

 there may be utility in an exposition which aims at being com- 

 prehensive and accurate, without being exhaustive or mathe- 

 matical. Simple the exposition cannot be, if one has any 

 ambition for thoroughness, but it is probably simple enough 

 for those who have got beyond the pottering, platitudinarian 

 stage, which deals in heredity with a capital H. My stacks of 

 unused manuscript remind me sadly of how much I have had 

 to leave out, to keep the volume approximately within the 

 limits of the series to which it belongs ; but the bibliography 

 will enable serious students to fill in details, and follow up the 

 clues I have given. It is arranged with a subject-index, so that 

 the literature dealing with particular points can be seen at a 

 glance. I have tried to avoid partisan handling of any theme, 

 though I have been at no pains to conceal my general adherence 

 to what is called Weismannism, or — to take a particular case — 

 my conviction that we do not know of any instance of the trans- 

 mission of an acquired character. I have also tried throughout 

 to keep the practical side of the study in view, but I have re- 

 frained from making many suggestions, in the belief that the 



