PREFACE ix 



vironmental relationships that any attempt to 

 criticize or correct leads inevitably into Lamarckian 

 problems and terminology. We must continue to 

 investigate environmental relationships, but they 

 may be studied in a spirit wholly different from 

 the controversial approach of the past, and here 

 lies the chief claim of this study. It is presented 

 as a non-partisan discussion of the existing state 

 of evolutionary theory in the hope of finding a 

 more logical approach for experimental work. It 

 has a Lamarckian flavor, but is neither Lamarckian 

 nor Darwinian in intent; I am interested only in 

 the sound investigation of evolutionary processes, 

 regardless of the names by which they may be 

 called. 



Such conclusions as I present here must neces- 

 sarily be the result of years of thought and of 

 many men's work. It is impossible to acknowledge 

 or even to realize the extent of one's obligation to 

 the many who collaborate through the medium of 

 their published works, but that the debt is great 

 I both realize and gratefully acknowledge. 



I wish to extend my thanks for permission to 

 use quotations from copyrighted works to the pub- 

 lishing houses of Henry Holt and Company, 

 Charles Scribner's Sons, Charles C. Thomas, and 

 the University of Chicago Press. My gratitude is 

 also due once more to my wife, Winifred Wood 

 Lindsey, for assistance in reading proof and for the 



