vni 



outside this sphere ! And moreover my investigations forced me to attribute 

 the great variety in colouring to evolutionary changes. As to evolution,— as 

 I have repeatedly stated, on p. xin of the introduction to my first monograph 

 as well as on p. xix of that to my last monograph, — since Darwin the word 

 evolution occurs everywhere, but a clear idea of what we are to understand 

 by that term is seldom met with. I was obliged to refer to this just now in 

 connection with the so-called tails of the Lepidoptera. Not only for the general 

 public, but even for most biologists, evolution is a hollow phrase. Whereas 

 formly the changes in animate creatures were attributed to supernatural influences, 

 which were supposed to regulate and control them, it is now thought necessary 

 to regard them as an expression of evolution. But the one is as vague to them 

 as the other. And while I was led to assume that these changes were due to 

 an independent, evolutionary impetus, and did not arise from the pressure of an 

 immediate necessity, that is of utility, or from the influence of surroundings, 

 although these might influence the further development of the process to a certain 

 extent, it was almost impossible for minds steeped in Darwinian or Lamarkian 

 ideas to accept this theory. To many the theory of an independent development 

 seemed necessarily based upon a mystical conception. Naturally if one regards 

 the colour as a phenomenon which is not of evolutionary origin, but created by 

 the above mentioned influences, it is also impossible to understand, how its 

 alteration can be caused by evolution, least of all when the ideas of what is 

 meant by evolution are very vague, as is usually the case. I may refer, for 

 instance, to the idea which I have formerly discussed, that an evolutionary change 

 must necessarily include an entire species, usually the nature of evolution is con- 

 sidered to be quite explained by the Darwinian theory of selection, as it is com- 

 monly accepted, frequently with more or less modification; while as a matter of 

 fact it only plays a very subordinate part in evolution. And other similar ideas. 

 Even the mutation theory which attracts so much attention at present rests in 

 my opinion upon a similar error. I shall return to this point presently. 



Although I might not, therefore, taste the satisfaction of seeing my theory 

 gain a wide popularity, yet the further I continued my studies, the firmer 

 became my belief in the soundness of my views. I am more than ever con- 

 vinced that without a knowledge of the process of colour-evolution it is impossible 

 to understand why the colouring, especially in many of the Lepidoptera, displays 

 itself in such rich variety. Sometimes the tints and their shades, especially the 

 way in which they are spread over the surface of the wings, are not the same 

 in races, or in the sexes, and even in individuals of the same sex of the same 

 species, on the other hand sometimes the variety is nearly or completely absent. 

 In fact sometimes, different species, even those inhabiting districts far removed 



