loo COLOUR 



the distribution of colouring matter in transverse lines or bars is the 

 phylogenetically older method, because natural and sexual selection 

 cannot Avell have affected the hidden parts of the feathers. On 

 the other hand, the striated downy or first plumage of the Gallinae 

 and Eatita3 has been already, by Darwin, taken to be a very old 

 stage. This appearance, however, as in Struthio, is not due to 

 striation of the single feathers, but to juxtaposition of colourless 

 and deeply pigmented downs. To judge from the growth of a 

 feather, the production of crossbars seems to be the older stage, 

 since they will result from the intermittent deposition of pigment, 

 while, on the other hand, the production of shaft-streaks is not yet 

 satisfactorily explained. At any rate, it must be borne in mind 

 that possibly various groups of birds have gone independently 

 through such stages, and that what is primitive or archaic in one 

 need not be so in all. But a strong proof of the soundness of 

 Darwin's views is that we are able to trace the pattern of the most 

 beautifully-adorned feathers of the Argus-Pheasant or of the Peacock 

 step by step backwards to longitudinal stripes, spots, crossbars, and 

 lastly to insignificant and simple irregular little dots. 



Natural and sexual selection, whether combining or striving 

 against each other, have worked marvels in plumage. Significant 

 colours, as for instance total blackness or whiteness, could be 

 developed only when higher intellectual qualities, bodily size and 

 strength, or occasionally even special smallness, guaranteed the 

 safety of the bird. The females and the young mostly retain a 

 more sombre garb, and thus remain on a phylogenetically lower 

 level. It takes the large Gulls several years to change from a 

 mottled brownish and grey appearance into the beautifully dark 

 and white colours. The same applies to the white shoulders of 

 certain Eagles \ and many other instances, too well known to be 

 repeated here, shew clearly how. the changes of bygone ages of the 

 ancestors are recapitulated in the yearly moult of the growing 

 individual until with maturity its present stage of perfection is 

 reached — ^but only its present stage, because its descendants in turn 

 will be different, either still more beautiful or still better adapted 

 to the ever-changing conditions of life. This consideration implies 

 that whole-coloured birds, like Swans and Kavens, have reached their 

 limit so far as coloration is concerned ; since both black and white 

 are very conspicuous and are correlated with a considerable amount 

 of intellectual development. The very early assumption of the 

 black plumage by the nestlings of Kavens and Crows is a strong 

 argument for their relatively highest position on the hypothetical 

 avine tree. Albinos are notoriously shy. The females of birds 

 which breed in holes, as Rollers, Kingfishers, and Parrots, are fre- 

 quently as beautifully coloured as the males, because they need 

 no protection through colour while sitting on the nest. In the 



