^80 Correspondence. 



Auk 

 Oct. 



guess-work, with no basis in experiment, microscopical study, chemical 

 analysis, or properly observed facts of any sort, as shown by Mr. Keeier's 

 own statements. He is speaking, or supposes he is speaking, of pig- 

 ment, but his remarks show that he refers to color in a broad sense. 

 Yet no blue pigment has ever been discovered, and green and yellow 

 are well-known to be not by any means always due to pigment, but are 

 merely 'objective structural colors.' Thus, according to Gadow, violet 

 and blue always belong to this category, green almost always, and yel- 

 low occasionally. And among the instances he cites where "yellow 

 feathers are in reality without pigment" are such birds as Icterus (.'), 

 Xanthomelas, Picas, etc. Green, except in the Musophagidre, "is always 

 due to yellow, orange, or grayish brown pigment with a special super- 

 structure, which consists either of narrow longitudinal ridges, . . . or 

 else . . . the surface of the rami and radii is smooth and quite trans- 

 parent, while between it and the pigment exists a layer of small poly- 

 gonal bodies, similar to those of blue feathers." Further space cannot 

 be given to the subject in this connection, but the reader is advised to 

 carefully study, in connection with Mr. Keeier's "theory of the assort- 

 ment of pigments," and related parts of his work, the article on 'Colour' 

 bv Dr. Hans Gadow in Professor Newton's recently published 'Diction- 

 ary of Birds,' from which some of the above statements are quoted. 



It is evident that if Mr. Keeler had possessed what may be termed even 

 a tair superficial knowledge of the investigations that have been made 

 respecting pigments, and the structure of feathers in relation to color, he 

 could not have propounded so utterly defenceless a hypothesis as his 

 •Law of the Assortment of Pigments," and would have omitted a great 

 deal of the "rubbish" that he has put into his book on the general subject 

 of the "evolution of colors" in birds. 



Many of the minor points in Mr. Keeier's rejoinder are passed over as 

 hardly demanding space for formal consideration, even though the real 

 bearing of my criticisms is in several instances greatly misrepresented. 



In conclusion I may add that the task of reviewing Mr. Keeier's book 

 was a painful one, and was prompted only by a sense of duty, not only 

 to the many inexperienced readers who might be misled by it, but as a 

 needed protest against a very prevalent kind of pseudo-science that has 

 of late gained great currency and popularity. That some such antidote 

 was not wholly unnecessary is shown by the fact that the editor of a 

 prominent scientific journal is found to have endorsed one of its most 

 groundless hypotheses. — J. A. Allen.] 



Birds of British Columbia and Washington. 



To the Editors of the Auk : — 



Dear Sirs: — Over the initials "C. F. B." there appeared in the last 

 number of 'The Auk' a review of my final paper on the Birds of British 

 Columbia and Washington. 



