6 THE EVOLUTION OF 



asserted against it that female preponderance always exists 

 among butterflies. And Prof. Dr. Eimer accepted that both, 

 male- and female-preponderance, exist, and founded there 

 on two of his so-called laws. Now against these three 

 opinions I alleged as the results I collected from the facts 

 of colour-evolution observed by me, that indeed botb phe- 

 nomena occur, but that it would be a mistake to derive 

 therefrom any constant rule or law, since they are merely 

 the expression of the enormous difference in susceptibility 

 for evolution — and thus in the course thereof — not 

 only between the familiae and genera but also between 

 the races, sexes and even individuals. This too is often 

 the cause of one sex sometimes presenting itself as more 

 or less primitive than the other. So in fact, in a biolo- 

 gical sense every kind of preponderance is excluded. This 

 now appears to me very different from what Miss N. 

 seems to have read in my paper. 



Further she says it seems to her a much simpler expla- 

 nation of the phenomenon which I denominated » colour 

 evolution" to accept that red, yellow and white as chemi- 

 cally nearly related original colours of Pieridae, are readily 

 converted into one another and tend to disappear, as the 

 dark pigments develop, replaced by the brilliant optical 

 colours which are apparently associated both with these 

 dark pigments and with the progressive differentiation of the 

 scales. Now it is my opinion that the strangeness of a new 

 view does not necessarily involve the evidence of its being 

 a false one; that indeed most new things look strange, 

 and that moreover the apparent simplicity of a superficial 

 explanation does not suffice in this matter for its being 

 substituted for the one I gave. Biological phenomena usu- 

 ally are brought about by the cooperation of so many 

 factors that indeed they are anything but simple, in fact 

 rather of a very complex nature, and therefore cannot be 

 explained in such a simple way. Besides that so called 

 simple explanation is not found to be confirmed by what 

 the study of butterflies teaches us. The transition of red 



Notes from the Leyden M.useut£i, Vol. >CXII. 



