EDITORIAL STATEMENT. VII 



The entire task of compiling and editing Chapter X, Voice and Instinct in 

 Pigeon Hybridization and Phylogeny, has been performed by Dr. Wallace ( 'raig 

 and Dr. Oscar Riddle. From the manuscripts and materials reviewed by them a 

 number of excerpts have also been taken and utilized, under proper designations, 

 in some of the other chapters. Dr. Craig, while studying pigeon behavior under 

 the author's direction, made a practice of taking notes of his remarks during 

 their conferences. From this material he has selected those observations closely 

 related to the topics under discussion. This material has been inserted in the form 

 of footnotes with the designation of "conv." 



Any editorial criticism, evaluation, or interpretation of the results has been 

 steadily avoided as far as possible. The single wish and hope actuating our labors 

 has been to present this material to the reader in a serviceable form and to leave 

 to him the final task of criticism and evaluation. Any evaluation of the material 

 at the present time must consider the date of these manuscripts. The work began 

 twenty-four years ago, two years before the appearance of Thorndike's monograph 

 on "Animal Intelligence," which publication is generally regarded as the first 

 experimental contribution to the subject of comparative psychology. Whitman's 

 work was thus begun shortly after the appearance of the initial works of such 

 authors as Romanes, Lubbock, and Lloyd Morgan. 



I wish to express my appreciation of the courtesies extended me by the Station 

 for Experimental Evolution of the Carnegie Institution of Washington, which have 

 made this labor possible. Acknowledgments are also gratefully rendered to Dr. 

 Riddle for his stimulating interest and suggestive help in the task. 



HARVEY A. CARR. 

 UNIVERSITY OF CHICAGO, January 1919. 



