218 



THE AMERICAN MUSEUM JOURyAL 



tains noble poetry; and as regards 

 mammals and birds Thayer's book con- 

 tains just about as mucli new scientific 

 truth as does Paradise Lost. To treat 

 his book as in this respect superior to 

 such a book as Dewar and Finn's, 

 stands on a par with ranking the noble 

 Miltonic poem of the creation as scien- 

 tificall}' above Darwin's Descent of 

 Man. Until we have attained the ele- 

 mentary knowledge necessary in order 

 to understand that the facts above out- 

 lined have been amply "demonstrated," 

 further biological discussion does not 

 tend to edification. 



My discussion 1 of revealing and con- 

 cealing coloration among birds and 

 mammals covers but a tiny corner even 

 of the question of animal coloration ; 

 but I do not think that it is possible to 

 controvert my main thesis, which is, 

 that as regards these higher vertebrates, 

 concealing coloration (with or without 

 countershading as a basis), as a sur- 

 vival factor working through natural 

 selection, has been of trivial conse- 

 quence in producing the special color 

 patterns on the great majority of birds 

 and mammals; that it has in an im- 

 mense number of cases been wholly in- 

 active, so that in very many of these 

 cases the animals are extraordinarily 

 conspicuous in nature at almost all 

 times, including the vital moments of 

 their lives ; and that in most of the 

 large number of cases where it has ac- 

 tually been a factor it has merely set 

 limits of conspicuousness. sometimes 

 very narrow, sometimes very broad, 

 which must not be exceeded, but within 

 which innumerable tints and patterns 

 are developed, owing to some entirely 

 different slant of causation. 



I have not tried to deal with reptiles 

 and batrachians as a whole, nor at all 

 with fishes and invertebrates. I am 

 very confident that as regards some 

 common land reptiles and insects which 



' See Bulletin of the American Museum of Natu- 

 ral History, August. 1911: Xfrican Game Trails, 

 Scribner's," 1910. Appendix, pp. 491-512; also 

 Life Histories of African Game Animals, Scrib- 

 ner's, 1914, pp. 54-148. 



] continually come across — black snakes 

 for instance, numbers of black or show- 

 ily colored beetles, and woolly cater- 

 pillars which are boldly marked with- 

 black and red or which are white — the 

 coloration has not the slightest con- 

 cealing, and probably has a revealing, 

 (juality ; that they are conspicuous. 



I am quite prepared to find that the 

 reverse is the case as regards many, or 

 even the vast majority, of the lower 

 forms of life, including especially all 

 those in which the individuals undergo 

 a rapid change of color corresponding 

 with the change in the color of their 

 backgrounds. It seems to me utterly 

 unscientific to try to generalize, nega- 

 tively or affirmatively, about all ani- 

 mals from observations on one highly 

 specialized group; and above all to try 

 to apply deductions from observations 

 made on such a group as that of the 

 coral reef fishes to groups of animals 

 like prongbucks or white goats, or os- 

 triches, or crows, or white egrets, or 

 scarlet tanagers, where practically every 

 condition is entirely different. In the 

 bay beside which I live are mollusks 

 with white, black, dark green, slate, 

 gold, silver and brown shells; and the 

 pebbles on the beach have about as 

 varied colors : but I do not try to gen- 

 eralize from the shellfish to the pebbles 

 or vice versa. 



There is ample room for genuinely 

 scientific study in order to find out 

 what coloration laws, if any, apply uni- 

 versally to Long Island Sound shell- 

 fish, to coral reef fishes, to land insects, 

 to reptiles, to forest and desert birds, 

 and to mountain and plains mammals : 

 and what laws apply only in one or an- 

 other group. But in order that our 

 studies shall be to good purpose, we 

 must be willing to face all the elemen- 

 tary facts, including our ignorance as 

 to most of them; and when once these 

 elementary facts have been shown to be 

 obvious, we must not waste time in re- 

 investigating them without sufficient 

 cause. November 15, 1917. 



