4 THE EVOLUTION OF 



the more so, if such au investigation is to be extended as 

 to other genera and even to families. So if one is not a 

 lepidopterologist possessed with this capacity such au in- 

 vestigation is not an easy matter. 



Now I presume Miss N. is not a lepidopterologist and 

 consequently has not been able to follow my observations 

 in a sufficient manner. Unfortunately this had led her into 

 a very superficial attack on my scientific work, thus obli- 

 ging me to utter a serious protest. 



The authoress seems to consider my theory of colour- 

 evolution in Lepidoptera as resting on a loose hypothesis 

 that has simply arisen in ray brain by contemplating over 

 so many butterflies. Now this is quite false. My theory is 

 not founded on mere guessing, but on a fact revealed to 

 me after long observation which, however, had not yet at- 

 tracted attention. Only so far as it is an hypothesis that 

 the embryological forms revealed by the study of the on- 

 togenesis of an animal do render also those of the phylo- 

 genesis of the species, does my theory also rest on an 

 hypothesis. My paper on colour-evolution in Pieridae is 

 not at all a thing by itself; it is founded — as I ex- 

 pressly stated therein — on the results of my former 

 studies of the colour and the polymorphism of caterpillars 

 of the Sphingidae. In that study, based on several ontoge- 

 netic observations made by myself as well as by others, 

 I had demonstrated pretty decisively, as I thought, that 

 the primary colour of all these caterpillars is in a state 

 of continual changing, having begun to do so even before 

 the differentiation of the family; and always in a definite 

 direction, but proceeding in every species and also in the 

 individuals in a very irregular way. Now with this change 

 neither the influence of environment nor natural selection 

 has any thing whatever to do, and that is why I con- 

 cluded to a hitherto unknown phenomenon of evolution 

 called by me » colour-evolution", a phenomenon by which 

 the difference of colour, as well as the polymorphism in 

 those caterpillars, easily can be explained. It has not been 



Notes from the l-.eydeii Miuseum, "Vol. ^J?<CII. 



