PREFACE BY THE EDITOR. V 



Having selected color-pattern in pigeons as supplying a relatively small group 

 of specific characters easily accessible to study, he first set about determining which 

 patterns are the more primitive and which the higher and more recent, each bit of 

 evidence being retested by search for the convergent testimony of various kinds 

 of evidence. A general survey was made of the color-patterns of the wild species of 

 pigeons, a group that includes nearly 600 species, besides nearly 200 domestic races 

 that have been derived from one or a few wild species. Large numbers of genera 

 and species from all parts of the world were brought to the breeding-pens of his 

 yard. There with much patience the patterns were studied from the living birds; 

 male and female were compared; the sequence of pattern in the plumages from 

 young to old was accurately observed; thoughtful experiments were devised to 

 bridge the gap between the molts and thus displace apparent discontinuities with 

 evident continuities; the behavior of many characters in hybridization was exten- 

 sively studied; and the primitive pattern of several diverse orders of birds was 

 ascertained. 



The direction of the evolution of pattern as it was indicated by all these studies 

 was, moreover, further tested by evidence of an entirely different sort. Such char- 

 acters as voice, behavior, and fertility were separately subjected to similar appro- 

 priate, comparative, and breeding tests to learn whether the resulting data would 

 parallel each other and whether all would parallel the data furnished by the exten- 

 sive study of the color-pattern. Only when Dr. Whitman had accumulated a vast 

 amount of consistent and convergent testimony as to where the various genera 

 stand in the phylogenetic series did he permit himself to feel that he was reading 

 aright the history of the specific characters of the pattern. 



In consequence, Whitman's work presents a large body of searchingly self- 

 critical conclusions; and these conclusions unquestionably lead far into constructive 

 evolutionary theory. For his material, he was convinced that he had demonstrated 

 the reality and regnancy of definitely directed variation — i.e., of orthogenesis — as 

 the method of evolution. He has accumulated the most weighty evidences for 

 continuity as against discontinuity in the phenomena of variation, inheritance, and 

 evolution. He has thrown new and extraordinary light on the nature and meaning 

 of "mutants" — such "mutants," at any rate, as occur among pigeons; and he has 

 made a brilliant and comprehensive analysis of the phylogeny of pigeons. 



Chapters I, II, III, IV, and X of the present volume were practically finished 

 by Dr. Whitman, and except for the addition of references to the illustrations and 

 the occasional insertion of a page or a few pages of supplementary matter — often 

 written later by him on the same subject — these remain practically unchanged. The 

 illustrations of Chapter X were descriptively united to the text by Dr. Whitman. 

 Nearly all of the other illustrations have been placed by the editor at those points 

 in the text which to him seemed necessary or appropriate. Chapters V to IX 

 inclusive required a complete rearrangement by the editor. The sources of this 

 material were quite scattered, as is indicated in connection with each chapter, and 

 some topics were not sufficiently treated. In other cases the subjects were studied 

 in the earlier years and it was found that later and more searching study had 



