V ° S L 3 X ] Correspondence. T>19 



whole organism, and thus involving, among other changes, the amount 

 and character of the pigment at the time of its deposition during the 

 formative stage of the feather. 



5. Any fair-minded reader who will take the trouble to see how the 

 phrase "slipshod generalization" is introduced will see that it lias no 

 necessary bearing on the case of the Brown Creeper, but relates directly 

 to his assumption that "the habits of birds have been more or less deter- 

 mined by their colors," and to his explanation of how they have been so 

 determined. In case there is any connection between color and habits, 

 it is habit that has determined color, according to the views of most evolu- 

 tionists, rather than color that has determined habit, which seems to be 

 purely a discovery of Mr. Keeler's. 



6. When Mr. Keeler has observed the living bird and found that when 

 the Pigeon spreads its tail it spreads only the rectrices and not the lower 

 coverts as well, it will be time to consider the point made in his rejoinder 

 as well taken. 



7. It is perhaps worth while to state that "the fact that the streaked 

 feather is the elementary type of feather marking" is not accepted as a 

 "fact" to the extent Mr. Keeler's positive statement might lead one to sup- 

 pose. Indeed, the opinion of several eminent investigators who have 

 recently expressed themselves on the subject is quite the reverse, both 

 Kerschner and Gadow, for example, believing that the distribution of 

 coloring matter in transverse bars and lines is phylogenetically the older 

 method. 



S. Professor Cope, in reviewing Mr. Keeler's work in the 'American 

 Naturalist' (June, 1S93, p. 459) has said: "The most important con- 

 tribution towards the discovery of the origin of colors in birds by Mr. 

 Keeler is his demonstration^ of the law of the Assortment of Pigments. 

 His classification of our birds in accordance with their color relations, 

 is a valuable preliminary to further research." But it is impossible for me 

 to believe that Professor Cope spoke from a due consideration of the subject 

 or from any intimate knowledge of the facts involved. His careless men- 

 tion of the matter is evident from his reference to Mr. Keeler's "demon- 

 stration" of his law, when Mr. Keeler tentatively puts it forth with the 

 usual ' it's ' and other qualifications, and says distinctly that the "theory 

 could not be demonstrated without further study of the chemical prop- 

 erties of pigment" ; and further adds : "Until such experiments have been 

 made, however, it is necessary to depend upon appearances, and here 

 there are many facts that seem to support the view." This, then, is Pro- 

 fessor Cope's "demonstration" of ''the law of the assortment of pig- 

 ments," which seems to give Mr. Keeler so much consolation. 



It is needless to say that I look upon this theory as no better than 

 numerous others I took the trouble to criticise, and almost regret that 

 I am now called upon to expose its worthlessness. It is based on pure 



'Italics mine, 



