COLOUR AND PATTERN IN ANIMALS 71 



or unconsciously, of preferring the most vividly marked. Sexual 

 conspicuousness, however, is a subject which does not specially 

 concern young animals, and it would be outside the purpose of 

 this book to discuss the theory of it at length. But it is interesting 

 to notice that where adult males are specially conspicuous, so differing 

 from young males and females, the latter usually resemble each 

 other and together resemble more primitive forms. This seems 

 to suggest that the sexual coloration is an instance of my third 

 grade of coloration, and is a relatively late acquisition, a thing 

 imposed on the more primitive patterns and colours. It is to be 

 noticed also that in a great many cases sexual coloration does not 

 conform with the growth and structural lines of the body, but has 

 much of the character of an artificial addition. 



It is quite possible that females may not exercise a conscious 

 preference in favour of conspicuous males, and that none the less 

 the conspicuous pattern is of advantage in attracting her attention. 

 The sexes find each other in many ways : by call- notes, by scents, 

 by coloration. I have been watching this afternoon the familiar 

 display of the males of two of the beautifully coloured pheasants. 

 The Peacock pheasant kept strutting round to face the hen, and 

 then stopped in front of her, hiding his dull-coloured breast but 

 showing the white tuft that hangs over his forehead in the breeding 

 season, raising and expanding the wings with their rows of blue 

 " eyes," and holding the tail erect and expanded, with the rows of 

 large green eyes shining in the sun so that the whole bird was a 

 gorgeous mass of spangles. The Amherst cock ran round the hen, 

 exhibiting himself sideways, raising the wing farthest from her, 

 depressing the one nearest her, and twisting the tail sideways so as 

 to show the greatest part of its coloured upper surface. The hens 

 in both cases were at first indifferent or reluctant, but the glittering 

 expanses of feathers soon excited their attention. So also brightly 

 coloured male butterflies mob a female, fluttering round her and 

 showing off to the best advantage ; whilst male spiders dance in 

 front of the females in such a fashion as to show off their colours. 

 Even if such decorations are no more than outcrops of structure and 

 surplus physiological activity, they are used to attract the attention 

 of the females and possibly to excite them. 



Conspicuous patches of colour, like sounds and scents, may be 

 useful as recognition marks, especially amongst gregarious animals, 

 or where the young follow the mother. Notable instances are the 

 yellow or white patches on the rumps of many deer and antelopes, 



