134 THE EVOLUTION THEORY 



row upon each side may depend upon the fact that the two rows 

 would be visible at the same time, and that they would blur each 

 other in the eyes of the swimming enemy, and so destroy the 

 resemblance of the picture to its unknown model. 



But it cannot be denied that there are characters which have 

 no special biological significance. There are doubtless many such 

 characters, which stand beyond the threshold of good or bad, and 

 which are therefore not affected by personal selection ; it is difficult 

 and often impossible to point these out with certainty. The shape of 

 the human nose and of the human ear, the colour of the hair and of 

 the iris, may be such indifferent characters whose peculiarities are to 

 be referred solely to germinal selection. On the other hand, I would 

 not venture to assert that the gay colouring and the complex markings 

 on the wings of our modern Lepidoptera are always and in all cases 

 unimportant, even when we cannot interpret their details either as 

 protective, or as a sign of nauseousness, or as mimetic. The usually 

 very exact similarity of the colour pattern in the individuals of each 

 species seems to point to the intervention of personal selection in some 

 form or other, for in what other way could such a large majority of 

 variations in the same direction have developed in the germ-plasm 

 as this constancy of the character indicates. 



We know, of course, that the colours of butterflies and moths can 

 be caused to vary through external and especially climatic influences, 

 but this would only account for simple modifications of colour, and not 

 for the origin of the complex colour patterns that actually occur. I 

 therefore believe with Darwin that sexual selection has had much to 

 do with this by giving a slight preference to the variations produced 

 by spontaneous germinal selection, and thus preventing the majority 

 of varied ids once acquired from being scattered again, but always 

 collecting more of them, and so securing free play for the increase 

 of the new character through intra-germinal processes. In this 

 way have arisen not only the brilliance of our Lycaenidse and of 

 the large Morphidse of South America, but also many of the coloured 

 spots, streaks, bands, eyes, and other components which have gradually 

 in the course of time evolved into the complex colour pattern of many 

 of our modern butterflies. I should like to remind any one who doubts 

 this of a fact which corroborates the view that personal selection has 

 co-operated in the production of these colours — I refer to the incon- 

 spicuous colouring of the females of many of these brilliant males — 

 while in contradistinction to these cases there are other species in 

 which both sexes are alike brilliant, so that it is impossible that mere 

 spontaneous germinal selection can have determined that the females, 



