464 TJie Descent of Man. Part II. 



With animals of all kinds when the adults differ in colcui 

 from the young, and the colours of the latter are not, as far as 

 we can see, of any special service, they may generally be 

 attributed, like various embryological structures, to the re- 

 tention of a former character. But this view can be maintained 

 with confidence, only when the young of several species resemble 

 each other closely, and likewise resemble other adult species 

 belonging to the same group ; for the latter are the living proofs 

 that such a state of things was formerly possible. Young lions 

 and pumas are marked with feeble stripes or rows of spots, and 

 as many allied species both young and old are similarly marked, 

 no believer in evolution will doubt that the progenitor of the 

 lion and puma was a striped animal, and that the young have 

 retained vestiges of the stripes, like the kittens of black cats, 

 which are not in the least striped when grown up. Many 

 species of deer, which when mature are not spotted, are whilst 

 young covered with white spots, as are likewise some few species 

 in the adult state. So again the young in the whole family of 

 pigs (Suidce), and in certain rather distantly allied animals, such 

 as the tapir, are marked with dark longitudinal stripes; but 

 here we have a character apparently derived from an extinct 

 progenitor, and now preserved by the young alone. In all such 

 cases the old have had their colours changed in the course of 

 time, whilst the young have remained but little altered, and this 

 has been effected through the principle of inheritance at corre- 

 sponding ages. 



This same principle applies to many birds belonging to 

 various groups, in which the young closely resemble each 

 other, and differ much from their respective adult parents. The 

 young of almost all the Gallinacese, and of some distantly allied 

 birds such as ostriches, are covered with longitudinally striped 

 down; but this character points back to a state of things so 

 remote that it hardly concerns us. Young cross-bills (Loxia) 

 have at first straight beaks like those of other finches, and in 

 their immature striated plumage they resemble the mature 

 redpole and female siskin, as well as the young of the goldfinch, 

 greenfinch, and some other allied species. The young of many 

 kinds of buntings (Emberiza) resemble one another, and like- 

 wise the adult state of the common bunting, E. miliaria. In 

 almost the whole large group of thrushes the young have their 

 breasts spotted— a character which is retained throughout life 

 by many species, but is quite lost by others, as by the Turdus 

 migratorius. So again with many thrushes, the feathers on the 

 back are mottled before they are moulted for the first time, and 

 this character is retained for life by certain eastern species 



