COLORATION 129 



and thorn-trees fringed the rare streams ; although the small 

 greenish or yellowish monkeys were common in these trees 

 near the streams of this dry, hot, open country. But in 

 the Lado, where the country was precisely like that into 

 which in East Africa they never ventured, and although 

 there were no forests such as elsewhere constitute their 

 dwelling-place, we found a form of the colobus, with the 

 black increased relatively to the white in the pelage, living 

 among the thorn-trees, precisely like the ordinary monkeys, 

 and likewise trusting for safety to galloping off over the 

 ground. Even in the great forests the colobus was far more 

 revealingly colored than the ordinary monkey; but in this 

 new habitat its color was an almost startling advertisement. 

 Neither from the standpoint of cover nor of food, nor of 

 climate nor of enemies, was it to have been expected that 

 the colobus would so completely change its environment 

 and life habits. 



It is necessary always to remember that it is impossible 

 to lay down laws regarding concealing coloration which 

 shall apply both to the higher and the lower animals. The 

 conditions are wholly different. A caterpillar which passes 

 its whole larval life on green leaves may be permanently 

 concealed by a green color. But a sharp-shinned hawk 

 hunts through woods and across open fields, over snow and 

 over green grass, in summer and in winter, through every 

 kind of landscape; and when it attacks it normally darts 

 with such velocity that its tint and pattern must be a mere 

 blur to its prey. It is evident to any serious thinker that 

 coloration may be all-important to the caterpillar, whereas 

 it must be of minor or negligible consequence to the hawk. 

 Again, a wood-frog or a tree-toad lives almost all its life in 



