THE USES OF AJTIMAL COL OB. 533 



the bottom of his cage. Evidently he was puzzled ; heretofore, 

 when he climbed those walls, he had invariably found a rest at 

 top — tin at one end and cardboard at the other; but this vast 

 expanse of light was a marvel to be* pondered and not too rashly 

 accepted. That mantis never did fly ; he crawled around the edge 

 of the cage at last to a spot where it touched a higher shelf of the 

 flower-stand, and, as if he had just discovered that he was a 

 prisoner no longer, scrambled with more haste than discretion up 

 to the next shelf, where a huge black spider, whose lair was just 

 under the verge of the shelf, pounced upon him so suddenly that 

 retreat was impossible. The mantis was taken completely by sur- 

 prise, and the start he gave was so violent that but for the spider's 

 swift, encompassing arms, he must have fallen backward off the 

 shelf. Thereupon ensued a terrific struggle ; the devil's-riding- 

 horse made a brave resistance, but the spider would have proved 

 too much for him, so his late jailer, armed with a broom-straw, 

 separated the combatants. The spider retired to the shadow of 

 the shelf, and the mantis, climbing upon the leaves of a mespilus- 

 tree that reached against the farther side of the flower-stand, dis- 

 appeared from our ken forever. 



-♦♦♦- 



THE USES OF ANIMAL COLOR.* 



By EDWARD B. POULTON, M. A., F. R. S. 



COLOR, as such, is not necessarily of any value to an organism. 

 Organic substances frequently possess a chemical and physi- 

 cal structure which causes certain light- waves to be absorbed ; or, 

 the elements of tissues may be so arranged that light is scattered, 

 or interference colors are produced. Thus blood is red, fat is 

 white, and the external surface of the air-bladder in certain fishes 

 has a metallic luster, like silver. In such cases there is no reason 

 why we should inquire as to the use or meaning of the color in 

 the animal economy; the color, as such, has no more meaning 

 than it has in a crystal of sulphate of copper or iron. Such colors 

 are the incidental results of chemical or physical structure, which 

 is valuable to the organism on its own account. This argument 

 will be still further enforced if we remember that the colors in 

 question are, strictly speaking, not colors at all. Blood and fat 

 are so constituted that they will be red and white, respectively, in 

 the presence of light, but they can not be said to possess these 

 colors in their normal position, buried beneath the opaque surface 

 of an animal. 



* From advance sheets of The Colors of Animals, by Edward B. Poulton, M. A., F. R. S. 

 International Scientific Series, No. LXVII. In press of D. Appleton & Co. 



