COLOR AXD PATTERN IX AXIMALS 399 



in such a case is to Ije sought in utility. The usefulness of 

 color in animate nature as an inspirer and satisfier of our own 

 ipsthetic needs and capacities, or of color patterns as means 

 whereby we may distinguish and recognize various sorts of 

 animals and })lants, is a usefulness which may be answer ciiougii 

 to the passing poet on the one hand, and to the old-liiK,' Lin- 

 ncean systematist on the other, but it is, of course, no answer 

 to science. Science demands a usefulness to the ccjlor-bejiring 

 organisms themselves: and a usefulness large and seriou.s 

 enough to be the sufficient cause for so highly specialized and 

 amazing a development. 



The explanations of some of the color i)henomena of animals 

 are obvious: some uses we recognize quickly as certain, some as 

 probable, some as possible. Some colors are obviously there 

 simply because of the chemical make-up of parts of the insect 

 body. That gold is yellow^ cinnabar red, and certain copper 

 ores green or blue, are facts which lead us to no special in(piir.y 

 after significance: at least, not after significance based on 

 utility. If an insect has part of its body composed of or con- 

 taining a substance tliat is by its very chemical and i)hysical 

 constitution always red or blue or green, we may be content 

 with knowing that, and not be too insistent in our demand to 

 the insect to show cause, on a basis of utility, for ])eing partly 

 red or blue or green. And even if this red or blue be dis})osed 

 with some symmetry, some regularity of repetition, either 

 segmentally or bilateraUy, this we may well attribute to the 

 natural segmental and bilaterally synnnetrical repetition of 

 similar body parts. Some color and some color pattern, then, 

 may be exphcable on .the same basis as the color of a mineral 

 specimen or of a tier of bricks. 



But no such explanation will for a moment satisfy us as 

 to the presence of and arrangement of colors in the wings of 

 Kallima, the dead leaf butteriiy, or in Plnfllium, the green leaf 

 phasmid, or in the butterfly fish, Cfuvtodon, or in the lichen 

 spider, or in the chameleon with its changing tints, or in any 

 one of a score of other more or less familiar forms whose color 

 pattern makes, even on the casual observer, an insistent 

 demand for rational exi)lanation. 



Certain uses of color seem apparent: tlie coIohmI eye flecks 

 or pigment si)ots of many of the lower animals i)resumal)ly 

 serve their possessors as organs by wliich to distinguish tho 



