252 A HISTORY OF BIRDS 



though generally coming into the world blind, naked and help- 

 less, yet frequently exhibit brilliantly coloured markings, gener- 

 ally confined to the mouth. These coloured areas belong to 

 another category, and will be discussed later. 



The down-clad nestling, there can be no doubt, represents 

 the more primitive condition, but it is not so easy to determine 

 whether in any case the primitive type of coloration has also 

 been retained, or whether what appear to be instances of primi- 

 tive coloration are really cases of adaptation to environment 

 independently acquired. 



That the dominant type of coloration among primitive 

 animals took the form of longitudinal stripes seems to be a very 

 widespread belief. These stripes are next supposed to have 

 given way to spots, and these latter either became re-arranged 

 to form transverse stripes, or mottlings, or disappeared alto- 

 gether, leaving a perfectly uniform coloration unrelieved by any 

 markings, or at least any very conspicuous markings such as 

 form a pattern. This orderly sequence seems to imply that 

 these patterns have followed an inherent line of development, 

 determined in the germ plasm, and encouraged, so to speak, 

 by natural selection. 



Eimer supposes "that the fact of the original prevalence 

 of longitudinal striping might be connected with the original 

 predominance of the monocotyledonous plants, whose linear 

 organs and linear shadows would have corresponded with the 

 linear stripes of the animals ; and further that the conversion 

 of the striping into a spot marking might be connected with 

 the development of a vegetation which cast spotted shadows. 

 It is a fact that several indications exist that in earlier periods 

 the animal kingdom contained many more striped forms than 

 is the case to-day. " This supposition," he goes on to say, " is 

 also supported somewhat by the fact ' that at present strongly 

 spotted forms mostly occur in places with spotted shadows, 

 the longitudinally striped more in grassy regions. . . . Cross- 

 marking is perhaps to be connected with the shadows, for 

 example, of the branches of woody plants — thus the marking 

 of the wild cat escapes notice among the branches of trees.' " 



That these several types of markings are, in many cases, 

 direct survivals enjoying a transient existence, like many other 

 vestigial characters, is highly probable, but in others they, with 



