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CONCKALINC-COI.ORATION IN THE AxiMAI. 



Kingdom. An Ex[)osition of the Laws 

 of Disguise through Color and Pattern: 

 Being a Summary of Abljott H. Thayer's 

 Discoveries. By (Jerald H. Thayer. 

 With an Introductory Essay by A. 

 H. Thayer. Illustrated by Abbott H. 

 Thayer, Cleraid H. Thayer, Richard S. 

 Meryman, and others, and with ])holo- 

 graphs. New Yorlc. The Macmilian 

 Company. 1909. Price, $7. 4to x.\+ 

 260 pages; 16 colored pages, 140 uncol- 

 ored figures. 



The fundamental importance of .\bbott 

 H. Thayer's law of obliterative or counter- 

 shading, in animals, first made known by 

 him in 'The Auk' for 1896 (pp. 124—129; 

 318-320), is recognized by all students 

 of the colors of animals. While it had been 

 applied in two instances by Poulton, 

 twenty years before, that eminent natural- 

 ist writes, "The far-reaching significance 

 of the principle was unseen until A. H. 

 Thayer's great discovery in 1896." "For 

 ages," the same writer remarks, "the 

 artist has known how to produce the ap- 

 pearance of solid objects standing out on 

 his canvas, by painting in the likeness of 

 shadows. It has remained for this great 

 artist-naturalist to realize the logical 

 antithesis, and show how solid objects 

 may be made to fade away and become 

 ghost-like, or even invisible by painting 

 out the shadows." (Essays on E\-olution, 

 Oxford, 1908, p. 299.) 



In the handsome volume under con- 

 sideration, Mr. Thayer's son, Gerald H. 

 Thayer, presents his father's further 

 elucidation of the law of counter-shading, 

 and the results of his additional studies 

 of concealing coloration. 



Mr. Thayer contends that the main, 

 if not sole function of color is for purposes 

 of concealment, in order that an animal 

 may either elude its enemies or capture its 

 prey. In 'warning,' 'recognition,' 'signal- 

 ing,' or 'banner' colors, he has no belief. 

 "This discovery," he writes (introduction, 

 by A. H. Thayer, p. 4), "that patterns and 

 utmost contrasts of color (not to speak of 



app(ii(l(ii:,(:s) on animals make wholly 

 for llicir ol)!iUTalion, is a fatal blow to 

 the N-arious theories that these ])alliTns 

 exist mainly as nuptial dress, warning 

 colors, mimicry devices {i. c, mimicry 

 of one species by another), etc., since 

 these are all attempts to explain an en- 

 tirely false conception that such patterns 

 make their wearer conspicuous. So im- 

 measureably great, in the case of most 

 animals, must be the value of inconspicu- 

 ousness, that such devices as achieve 

 this to the utmost imaginable degree, 

 upon almost every living creature, de- 

 mand no further reason for being (although 

 doubtless serving countless other minor 

 purposes)." 



Among birds, it is said, inconspicuous- 

 ness or concealment is achieved; with 

 but few exceptions, primarily by counter- 

 shading, usually aided by markings, 

 patterns or appendages which tend to 

 further obliteration. 



The law of counter-shading, which 

 explains how an animal is rendered incon- 

 spicuous by being darkest above, where it 

 receives the most light, and palest below 

 where it is least lighted, is accepted as a 

 demonstrated principle, and it now too 

 well known to call for comment here. 



In the newly proposed law of oblitera- 

 tive coloration, the invisibility of the 

 counter-shaded bird is increased by the 

 addition of a picture pattern, b}' which 

 the bird is made to resemble the back- 

 ground against which it is most commonly 

 seen by its enemies or by its prey. Or, 

 to quote the author, "The object's ob- 

 literatively-shaded surface must bear a 

 picture of such background as would be seen 

 through it if it were transparent" (p. 31). 



Thus, the American Woodcock bears 

 on its plumage a picture-pattern of "dead 

 leaves, twigs and grasses, variously dis- 

 posed over shadow-holes, in a near view,'' 

 while the markings on Wilson's Snipe 

 represent "sticks, grasses, etc., with their 

 shadows, at various distances." The 



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