PREFACE BY THE EDITOR. 



At the mature age of 50 years Professor ( 'harl. , < Mis Whitman l>cgan tin- work 

 now presented in these volumes, and the long task was still incomplete ul.m, 18 

 years later, on December 6, 1910, a brief illness terminated the work and lit 

 this investigator, to whom biology and many American biologists especially are so 

 much indebted. 



After six years, the efforts of some of his friends to make the results of his long 

 labors available to others are nearly concluded. This t:isk has IM-.-M n< Tessurily 

 shared by a number of persons and organizations, and UK- demands upon -nun- of 

 them have been so considerable and unusual that the nature of their endeavors is 

 here most gratefully acknowledged. 



The continued maintenance of the large collection of pi. i|>on which this 



series of studies was based was essential to a presentation of anything more than 

 a fragment of the results; it was necessary to learn the term of life and the se\ of 

 all the surviving individuals; and further breeding or testing of certain " mutants" 

 among them was scarcely less urgent. This formed one of a number of h 

 exactions upon those who have felt the necessity of presenting the largest possible 

 portion of the author's results. The whole of these and other obligat ions, during tin- 

 first year, was shared by Mrs. C. O. Whitman and by the editor, who was gem-ro 

 assisted by unasked grants from the A. A. Sprague Institute of < 'hicago and 

 from the Laboratory of Experimental Therapeutics of the University of ('hicago. 

 During the five following years the Carnegie Institution of Washington has fully 

 maintained the work during two years at Chicago and for the -uci-.-eding ti 

 years at the Station for Experimental Evolution at Cold Spring Harbor. New York ; 

 that Institution has also assumed the entire expenditures incident to the publication 

 of these volumes. For all this generous assistance the editor expresses enduring 

 obligations. 



Not more than one-fifth of the matter herewith presented was found to 

 approach a stage of readiness for publication; it has required some years to bring 

 the results to their present form. Even now we have been unable to utilize all 

 of the records and data, and many of the carefully prepared illustrati- 

 also omitted. If our progress in the preparation of these materials has seemed 

 lingering and slow, it should be said that much time has been given to all those 

 materials which proved impracticable for use as well as to those which are now 

 incorporated in the work. It was, however, in some cases found obligator 

 become familiar with a subject as to which only records and raw data were avail- 

 able. Again, other and nameless difficulties have sometimes attended our ell 



In the task of preparing the various materials for publication the editor found 

 himself wholly unprepared to deal with the manuscripts on Behavior in ! 

 Professor Harvey A. Carr has most generously carried that work to completion and 

 these studies are grouped to form Volume III. The special materials on vo, 



