858 



This view can be backed by numerous arguments. First it is 

 seen in several groups of motlis and butterflies that the light and 

 darli shades are substitute for each other, some species showing- 

 dark spots on a light ground, others near akin to them light spots 

 on a dark one. Obviously the connection between these two cases 

 is not such that the dark spots in the species of the first group 

 have grown light in those of the second, while the light ground 

 colour at the same time darkened, but quile the contrary, that the 

 dark spots grew larger and entered into connection with each other, 

 thereby forming a network in which the remnants of the light 

 ground-colour remained as isolated spots. Compare e. g. Rhyparia 

 piirpurata with Calliniorpha doniinula and Arctia viilica. 



In the same way as rows of spots can coalesce and form bars, 

 the dissolving of the original design may proceed further and lead 

 to complete selfcolour. An intermediate stage in this process is 

 formed by ihe coalescence of part of the markings so as to form 

 a groundcolour, while the rest of the spots stand out against it. 



Neither does there exist a fundamental difference between light 

 and dark colouring matter: black spots in one species being repre- 

 sented in an allied one by such of an identical shape and place, but 

 of a diffei-ent hue. 



Generally" this change in the shade of spots does not occur 

 simultaneously over the whole of their surface, but starts from their 

 centre and spreads to their circumference, this giving rise to annular 

 spots with a light centre and a dark ring. In \\\e genera, Ecpant/ieria 

 and Halesidoia all stages of this tiansformation may be found side 

 by side in one and the same individual, and on comparing various 

 specimens of the same S|)ecies, it appears that the identical spot is 

 entirely diirk in one, annulated with white core in the other. Nor can 

 arguments be detected for ascribing a different character to dark spots 

 with a light ring, as in Anjina, in comparison to light spots with a 

 dark one. Consequently in my opinion, when considering the genesis 

 of wing design, no plausible reason can be found to distinguish 

 betw^een spots of a more active behaviour in the transformation of 

 the pattern, and a ground colour that plays a more passive lole. In 

 the Hepialids for instance the pattern is formed by the regular 

 alternation of biconvex and biconcave spots, forming what I have 

 called the 0X0 motive of wing design, these spots being equi- 

 potential in so far as they undergo similar modifications in colour, 

 size and arrangement, under the influence of identical causes. 



So I cannot agree with dk Meyere's view, who considers the 0- 

 spots as the markings, the X-spots howexer as the areas of ground 



