442 PACKARD— ORIGIN OF MARKINGS OF ORGANISMS. [Dec 2 



Colors of Deep-Sea Crustacea. — Alcock also remarks thatVhile in 

 tiie decapods dredged in abyssal waters the colors were red, pink, 

 orange, yellow, a few brown, purple and white, none were spotted, 

 striped or with variegated patterns. Thus they entirely differ from 

 shallow-water forms with their freaks of color or labyrinthine 

 mottlings and dapplings. 



19. Thayer's Law and His Experimental Proof. 



In a suggestive article on protective coloration Mr. Abbott H. 

 Thayer^ considers the subject from an artist's point of view. 

 '* Animals," he says, '* are painted by Nature darkest on those parts 

 which tend to be most lighted by the sky's light, and vice versa.'' 

 The prevalent idea of protective mimicry, he says, makes an animal 

 appear to be some other thing, whereas it makes it cease to appear 

 to exist at all. 



The colors of the ruffed grouse are a complete gradation from 

 brown above to silvery-white beneath. It grows light under the 

 shelving eyebrows and darker again on the projecting cheek. 

 When it stands alive on the ground its obliteration by the effect of 

 the top light is obvious. By extending its protective color all over 

 it, treating the under side with brown to match its back, the bird 

 was made distinctly visible. 



Thayer proved this by the following experiment. He had about 

 a dozen egg-shaped pieces of wood made of the size of a woodcock's 

 body. They were mounted on wire legs to poise six inches above 

 the ground. Most of them he painted in imitation of the color 

 gradation of a grouse or hare — earth color above to pure white 

 beneath — while to two others he gave a coat of earth color above 

 and below. He then set the whole lot like a flock of shore birds 

 on the bare ground in a city lot, and invited a well-known orni- 

 thologist to look for them at a distance of from forty to fifty yards, 

 who at once saw the two monochrome ones, but, although told 

 exactly where to look, he failed to detect any of the others until 

 within six or seven yards of them, and then only by knowing 

 exactly where to look. He also painted bright blue and red spots 

 on the brown back of one of them, which spots only passed for 

 details of the ground beyond the ^gg. 



1 " The law which underlies protective coloration," The Auk, xiii, April and 

 Oct., 1896. Also Smithsonian Report iox 1897, p. 477. 



