28 ANIMAL COLORATION. 



On tlie whole, however, it is clear that there is a great deal 

 to be said for many of the phenomena of progressive change in 

 coloration being advantageous, and therefore conceivably due 

 to the action of elimination of unfit varieties. 



Mr. Poulton has studied the life history of a caterpillar 



belonging to quite a diiferent group of moths— the Geometry.* 



The adult larva of Selenia illunaria (one of the "thorn 



moths ") has the usual twig-like appearance and coloration 



found in the group to which it belongs. 



When first hatched, the caterpillars are almost entirely black, 

 with four transverse white stripes ; these stripes gradually 

 disappear, and the ground colour becomes browner. Daring 

 the early stages the attitude, as figured by Mr. Poulton, would 

 seem to render the caterpillar rather conspicuous ; the twig- 

 like attitude assumed during later stages would probably be 

 more advantageous in the earlier stages in spite of the colour. 

 In ifact, it is difficult to see any adaptation of colour and colora- 

 tion in this first stage. 



It is still harder to detect any meaning of this kind in the 

 colour changes of some birds and mammals. The Tapirs are 

 for the most part of a greyish-brown colour, which is uniformly 

 distributed. The Indian species has, on the other hand, a 

 good deal of white on the under parts. 



Now, the young Tapirs are invariably spotted with white 

 spots on a brownish ground colour ; the brown is decidedly 

 diiferent from that of the adult animal. In the same way the 

 young of many Carnivora differ from their parents ; the young 

 Lion is distinctly spotted, and traces of this are to be seen 

 in the adult — particularly in the female; in relation to this fact 

 it must be remembered that the female is less differentiated 

 than the male. The young Puma is even more darkly spotted 

 * Trans. Eidomol. Sue, 1885, pp. 309 et seq. 



