XIX 



is, such as in regard to colour-evolution stand, so to siiy, on the very line of 

 demarcation between both forms, or, the degree of development of which in 

 this respect is but little behind that of the ^ form. Now this, since these 

 specimens are found as well at the same time as some ^ form ones in the dry 

 season, is the very thing I stated about the ocellar spots of Cyllo Leda L. 

 and mentioned on page XVI. So that, in fact, what this comparative study 

 has taught me, did fully confirm the afore-said, namely : that no pecuHar 

 wet and dry season forms may be admitted, though butterflies of the same 

 species found in those different periods, may mutually differ a little in degree 

 of evolutional alteration. 



It has also to be noticed here that in Java it often happens that dwarfish 

 Pieridae and also other Rhopalocera are caught which entirely correspond with 

 such as can be artificially bred by insufficient feeding of the caterpillar. It is, 

 however, to be doubted whether this dwarfish development is excited by the 

 same cause, as I have also caught such specimens in the middle of the rainy 

 season. 



So we see that we must be very careful in admitting these season forms 

 and that the wild exaggeration of nowadays in this respect — much of which 

 is due to the pursuit of gain by the dealers in insects — can not be called 

 scientific. An equalization with what happens in Europe in this respect by the 

 great difference between summer and winter, is altogether wrong. We must 

 not forget that in many tropical butterflies as f. i. in those of Cyllo Leda L. 

 already mentioned, the generations succeed each other uninterruptedly, also 

 during the dry season ; though probably during that time the progress is slower 

 in the wet season when among some butterflies a generation from egg to egg 

 comes to an end within a month, which does not prevent, however, the time 

 necessary for the development of the insects from sometimes varying a good 

 deal. From larvae, pupated at the same time one part will sometimes give 

 the butterflies after one week, the other part only after months, even after eleven 

 months. And such under evidently the same circumstances; here also the 

 individual susceptibility plays its part. The European colour-dimorphism of 

 Araschnta Levana L. with the form Prorsa L. is nothing but a phenomenon 

 of colour- evolution in which, however, not the lesser value of the food, but the 

 cold prevents its further development of colour as happens in the said case 

 with the ocellar spots of Cyllo Leda L. 



Best of all may the process of colour-evolution among the butterflies be 

 studied in the genus Iphias Bsd. (Hebomoia Hb.). Because the numerous 

 species or races of this genus really only differ in colour, so that it is doubtful 

 whether it is here a question of species or only of races; at all events, if we 



