51 



a certain process of development, and that this utterance, though the progress 

 of this process remains the same, complies in all kinds of manner with the 

 circumstances and in this way causes that great variety, which is the charac- 

 teristic of every evolution. It is the same dissimilarity, which may be observed 

 here in the process of the colour-evolution, which has been indicated above 

 concerning the atrophy of the so-called horn peculiar to the larvae of the 

 Sphingidae. 



When in the exhumations in Egypt pottery is found ornamented in different 

 manners, people not acquainted with archaeological matters will only consider 

 it as objects made with more or less care and ability, but the expert will know, 

 according to the age of the layers in which those pieces are found, to deduce 

 from them the whole development of the art of pottery. By comparison of 

 such objects from different layers for instance, it will become clear to him how 

 the ornamentation with imitations of plants has really only been a development 

 sprung from an older system of ornamentation with crossed lines, and that this 

 latter has arisen again as an imitation of the plaited baskets which were used 

 before the art of pottery had been invented, and which served as a model 

 for the first productions of this art. In the same way does the study of 

 colour-evolution show the origin of the present ornamentation on the wings of 

 butterflies, but the lepidopterologists of our days as a rule understand just as 

 little of it as the ignorant people above-mentioned concerning archaeological 

 matters. To them all these colour-patterns are only the fantastic result of some 

 climatical or other unknown influence. 



For a long time more red may still be recognized in the yellow of the 

 under-side than in the colour of the upper-side. Gradually, however, all the 

 yellow turns into white, first on some parts of the wings and afterwards on 

 their whole surface, while at the same time the black spreads over it, which 

 fact is very strong in some countries. Here also the evolution proceeds very 

 irregularly in different regions. In many $ from Celebes and from the isle of 

 Salaiara the black on the upper-side has increased so much, that it covers a 

 great part of, or sometimes entirely, the ground colour which is now bright 

 yellow and then white. But there occur also yellow 9, on which the black has 

 not spread itself more than on those of Java. Some 9 of Java, the ground- 

 colour of which has also become white already, but in which the black has also 

 increased, show along the costa of the fore-wings on the upper-side also that 

 peculiar thick stripe which marks the beginning of the increase of the black, 

 and which sometimes also in connection with a black dot on the fore-wings, 

 forms the hooked stripe, which has already been treated of in the Introduction. 



It is evident that among the </ the said process has not always and everywhere 



