Craig, Expressions of Efuotioji lu Pigeons. 31 



sexual selection takes account of only a fragment of the great utility 

 of the voice. Voice and gesture are of prime importance through 

 all the cycles of the life-history. This is shown, but not at all fully 

 explained, in the present paper. It is somewhat further shown in the 

 following (N^o. 6). 



6. Sociology. A preliminary account of the sociologic interpre- 

 tation of pigeon behavior has already been published.^ 



7. Psychology. The psychologic conclusions are so numerous 

 and so intimately connected with the details of description, that it 

 is impracticable to summarize them in this place. 



My indebtedness to Professor, Whitman is so evident from begin- 

 ning to end of the paper that there is no need to speak of its details. 

 1 wish, however, to acknowledge in gratitude the two chief debts I 

 owe to him. In the first place, Professor Whitman knows the 

 emotions, the voices, and the gestures of the pigeons very much better 

 than I do; he has told me a great many facts about the birds which 

 my more limited experience has not afforded; and he has always 

 given helpful answers to my questions as to what a bird is thinking 

 about when it does a certain act. In the second place, more im- 

 portant than the facts, I owe much to Professor Whitman for the 

 influence of his spirit of research. Enthusiasm and steadiness of 

 labor, sympathetic insight into the animal mind, patience with details, 

 yet a constant reference to general problems, I hope I have learned 

 to some degree. I wish to express grateful obligations also to the 

 University of Chicago and to the Marine Biological Laboratory at 

 Woods Hole, especially for that freedom which allows a student to 

 develop his own ideas. 



DESCRIPTION OF SOUNDS AND ACCOIVIPANYING MOVEMENTS. 



Prefatory Remarks. 



There is among scientists a widespread impression that bird-songs 

 are not susceptible of accurate description. But this impression is 



^The voices of pigeons regarded as a means of social control. The American 

 Journal of Soeiologj-, Vol. 14, 1908, pp. 86-100. 



