XXI 



individual, but in proportion to its conditions of life and to its susceptibility to 

 this power which constantly varies in individuals. Hence each individual 

 assumes an independent station in the course of these evolutionary processes 

 and amongst the individuals, therefore, all stages may be encountered formino- 

 transitions to one another. Now in the same manner as the cinematograph, 

 by the combination of a number of impressions of successive stages, reproduces 

 a whole occurence in its natural sequence, the individual colour patterns indi- 

 cate to the person, possessing sufficient lepidopterological knowledge to combine 

 them, how this process of colour change, of which each pattern represents a 

 specific stage, operates. 



Colour evolution teaches us how to explain the origin of existing colour 

 variety, somewhat in the same manner as embryology and comparative anatomy, 

 from forms in various stages of development existing side by side; it teaches 

 this, however, by observing the living forms and its study is thus identified with 

 that of the nature of evolution in general in which so much remains to be 

 elucidated, and is, therefore, of far-reaching importance. 



Recently I read the following sentence, written by a naturalist : " The whole 

 colour question of the plumage is one of evolution " . With the colours of 

 Lepidoptera it is the same. Nothing is further from the truth than the super- 

 stition so general amongst zoologists, against which I have already protested on 

 page vi of the Introduction to my Monograph of the Java Pieridae, that the 

 colour of animals is accidental, devoid of biological value and, therefore, not 

 susceptible to evolutionary change. But all this and consequently the pheno- 

 menon of colour evolution is, of course, scarcely comprehensible to those to 

 whom evolution is, as I stated, not much more than a term. Recourse is then 

 had to unknown influences which, even if they be termed meteorological, differ 

 litde in reality from the supernatural with which the uncultured satisfies his 

 lack of knowledge. 



A great part, in this connection, is probably played by a certain pedantic 

 shallowness, unfortunately, far from uncommon, which, however, assumes a 

 decided scientific guise and as such may exercise much influence on the semi- 

 learned. This manifests itself in the, to my mind unwarranted, weight attributed 

 to the only objection, of any importance, raised against my theory of colour 

 evolution. According to this theory, as I have summarily explained on page ix 

 of the Introduction of my Monograph of the Java Pieridae, the original pigment 

 was red, which gradually faded to white until the pigment disappeared in the 

 scales, and during this process a black pigment, moreover, increased at first 

 and then decreased. It is objected to this that the ontogenetic investigations 



