COLORS AND MARKINGS OF ANIMALS 



441 



thus shingled above and below (fig. 228) by thousands of 

 tiny scales which produce all its colors and markings. These 

 colors are made in two ways; either the scales are actually 

 brownish or reddish or yellowish or black themselves be- 

 cause they contain pigment granules inside, or else they 

 reflect white light in such a way that it is broken up, as by a 

 prism, into colors, only some of which reach our eyes. The 

 metallic and iridescent kinds, the greens, blues, coppers, 

 purples, etc., all of which change somewhat as we change 

 the position of our eyes, 

 are produced in the second 

 way. The duller and the 

 fixed colors, such as the 

 reds, yellows, browns, etc., 

 are produced by scales con- 

 taining pigments of the same 

 shade. 



Colors of other animals. 

 — ^The colors of other ani- 

 mals are also produced in 

 one or both of these two 

 ways; that is, either by col- 

 ored pigment, or by reflec- 

 tions from structures which 

 act as the prism does. 

 Only a few other animals have scales, and almost no 

 others have scales just like those of the butterfly, but they 

 have other kinds of structures on the outside of the skin, 

 such as feathers or hairs, which contain pigment, or break 

 up white light into colors. 



Observe the coloring on a blackbird; note the fine iri- 

 descent blue and purple or bronze-green reflections. These 

 are made by the feathers reflecting broken-up white light. 

 Such iridescent colors produced by structure, and hence 

 called structural colors, are especially pronounced and 



Fig. 227. Bit of rubbed wing of a 

 butterfly, Grapta sp., greatly mag- 

 nified, to show the rows of scale 

 insertion pits op both upper and 

 lower sides of the wing. 



