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Not being acquainted, or only slightly so, with my observations concerning the 

 colours in Rhopalocera and the manner in which they change in individuals, 

 investigators have worked in this respect not only without reference to these 

 observations but even with a total disregard of them ; a different line of research, 

 as well as a careful selection of material specially adapted for investigation 

 would have been a great desideratum in this connection, but haphazard 

 work has mostly been undertaken in this respect which, moreover, is strongly 

 biassed for the greater part by false theories, such as those of mimicry and 

 natural selection, or those of the German Professor Dr. Eimer, and endeavours 

 above all to seek confirmation of the said theories. Where, for instance, the most 

 accurate of these investigators, Alfred Goldsborough Mayer, actually pays 

 much attention to the colour pattern of the mature imagines, he simply follows 

 Baieson and his wholly unexplained fantastic principle of variability, but is 

 unable to conceive these colour changes as being the expressions of evolutionary 

 processes in a specific direction. I am unable, therefore, to attach much value 

 m this respect to his investigations but I consider it of interest to draw attention 

 to one or two points in them which prove clearly that his very accurate obser- 

 vations, although not, in my opinion, correctly interpreted, agree with my 

 own as regards the process of colour evolution. In his chapter " General 

 summary of results believed to be new to science " he says under (8) {a) '• when 

 in process of disappearance, bands of colour usually shrink away at one end". 

 This agrees entirely with what I have noted when discussing the first commence- 

 ment of the formation of the spurious eye spot in Cyllo Leda L. And again 

 under (12) "A record of the characteristic markings upon the wings of the 

 Danaid and Acraeoid Heliconidae shows that, physiologically speaking, the 

 colours red, rufous, yellow, and white are closely related and that black is 

 quite distinct from these, being the least variable colour of all". This, surely, 

 is just what, according to my observation, constitutes such a prominent fact in 

 the theory of colour evolution. 



I believe that with a view to the experimental ontogenetic investigations 

 referred to, attention may be drawn to a phenomenon which in my opinion is 

 too much neglected. It is true I do not attribute very great value to it but it 

 will not be amiss to consider it. I refer to what occurs in the appearance of 

 the mature colours. It is known especially in Coleoptera that after reaching 

 the mature stage their colour still requires some time before being completely 

 developed. Something similar I observed, as stated on page 62 of my Mono- 

 graph of the Java Pieridae, in the larva of Terias Hecabe L. Until the last 

 moult the larvae of this butterfly and those of T. Sari Horsf. have the heads 

 of the same colour as the body generally, /. e. green. But whereas in T. Sari 



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