Vi PREFACE BY THE EDITOR. 



thrown other or additional light on these topics. Several complete addresses by Dr. 

 Whitman were found to repeat statements elsewhere given; these have been either 

 entirely omitted or certain paragraphs have been transferred to a position in one or 

 another of the present chapters where the same topic is discussed. 



In some instances the editor has added statements of his own, but it is thought 

 that the reader will never be in doubt as to the source of a statement. In all those 

 chapters in which the present arrangement is wholly that of the editor, and where 

 he has drawn material from manuscripts or folders variously designated by the 

 author, references to those original folders are made at various points within the 

 chapter or at its close. All of these original folders will be permanently filed with 

 the Carnegie Institution of Washington, either in Washington or at the Station for 

 Experimental Evolution at Cold Spring Harbor, where they will at all times be 

 easily accessible to all interested parties. 



The reader will find that the literature of some of the subjects considered here is 

 not adequately treated. It will be easily granted, however, that since the author 

 did not arrange these parts of the manuscript for publication, it would be unwise 

 or impossible for another to go far in an attempt to do so. 



To the two artists, Mr. K. Hayashi and Mr. Kenji Toda, whose skilful and 

 numerous productions assist so much in the presentation of these studies, the 

 author would, I am sure, have recorded his warmest gratitude. 



The editor readily acknowledges that the imperfections of form of the work as 

 it now appears are assignable to him, and not to the author; but if what he has done 

 lacks the finish and completeness of all that which the author had made ready for 

 publication, it is hoped that a full measure of indulgence may be granted for imper- 

 fect results in the rather difficult endeavor to make available material that other- 

 wise must have been wholly lost. But even while deploring the imperfections of 

 his work, he avows it under the circumstances the great pleasure of his life to 

 have been able to assist in presenting the message of his colleague and master to 

 those for whom the labors of many years had pledged it. 



OSCAR RIDDLE. 

 STATION FOR EXPERIMENTAL EVOLUTION, 



Cold Spring Harbor, December 1916. 



