

INTRODUCTION. 



In the preliminary observations prefixed to my study on the Java Pieridae, 

 I expressed my intention to enter into a more particular discussion of various 

 biological facts or phenomena — though, in a general way, these also concern 

 the Rhopalocera or even the Lepidoptera — when treating of the families in 

 which these facts or phenomena stand out more clearly, either on account of 

 their frequent occurrence, or because they are very obvious or particularly 

 suitable for observations in them. Indeed, by thus uniting such discussions with 

 the treatment of certain families, I can at the same time indicate more easily 

 the examples with which my considerations in this respect are concerned and 

 mostly illustrate them with figures, without which such considerations always 

 remain obscure for many a one. Thus, in connection with the treatment of the 

 Pieridae I discussed especially the subject of colour-evolution and the pretended 

 tropical seasonal influences. 



Also with regard to the Hesperidae^ some observations may now be made 

 about the phenomena of colour-evolution. These butterflies are of course subjected 

 to the same evolutionary changes, but only in a few species is this distinctly 

 visible. The Koruxhaiolos Xanites Butl. e.g. have preserved on a part of 

 the fore-wings the original red colour, while for the rest the upper-side of the 

 fore-wings has been entirely darkened by the increase of black pigment. Hence 

 this red colour forms there a band the extent of which, however, differs very 

 mucli in different individuals and the colour also fades from dark orange into 

 lighter shades, whilst in other species the same evidently happens in the more 

 advanced stadia of orange, yellow and white. Thus among the species living in 

 Java such a yellow band is found on Celaenorhinus Dhanada Hb. which 

 has faded into white in other Celaenorhinus species and also in NoTOCRYFrA 



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