H2 CHILDHOOD OF ANIMALS 



Although the instances I have given are the merest samples 

 of the fertile diversity of colour and pattern displayed by birds, 

 they show the chief types of relation between the characters 

 of males, females and young. It is possible to build up from them 

 a general picture of a process that appears to have been going on. 

 The older or ancestral types of birds displayed a plumage generally 

 brownish in colour with little difference all over the body, and with 

 patterns of spots and stripes and mottlings. At first the colora- 

 tion of the young and of the adults in both sexes was more or less 

 alike. Next, during the breeding season, the males began to assume 

 brighter colours, and when the breeding season was over relapsed 

 again into the dull coloration of their ancestors. In such a stage, 

 the males in eclipse, the females and the young were all much alike, 

 and traces of this condition survive in many existing groups. Next, 

 the bright breeding plumage was partly assumed by the females as 

 well as the males, but after the breeding time was over, both relapsed 

 to the ancestral eclipse condition. In this stage, the males and 

 females in eclipse and the young were like the ancestors. This 

 stage too is retained by many birds, and the curious cases where the 

 females have shot ahead of the males is only another variation of 

 it. Next, the breeding plumage was retained for a longer and 

 longer period, for half the year as in the weaver-birds, for all but a few 

 weeks as in game birds and most of the ducks, or for the whole year 

 as apparently in the South American tropical ducks, in kingfishers 

 and in parrots. There are traces of its gradual suppression ; in 

 some of the game birds and in some of the tanagers, for instance, the 

 eclipse is represented by only a few feathers. When the eclipse has 

 been suppressed, it is only the young birds that retain the dull 

 ancestral plumage, and there is every stage of the suppression even 

 of that in the young. 



And so the general trend amongst birds and mammals alike has 

 been from dull colours and mechanical patterns to brilliant and 

 fantastic garbs. The obscure dusky browns and greys may be com- 

 pared with the coal-tar residues from which chemists have separated 

 and distilled a series of vivid aniline dyes. In a sense, all the 

 shining colours of the rainbow lie concealed and confused in the 

 turbid mother-liquid, and it is only by separation and recombina- 

 tion that the individual colours are obtained. And so in a sense, 

 perhaps rather an exact sense, the obscure hues of primitive animals 

 are accidental residues or waste products of the living chemistry of 

 the body, and it is only when they have been split up and separated 



