Dec , X903 1 Weeks: Evolution of Secondaries ok Catocala. 228 



sessed of more wing to sacrifice had just so much more chance to escape, 

 while those possessed of abbreviated wings would in the ordinary course 

 of existence be first destroyed, and consequently those individuals in- 

 heriting a tendency to enlargement of the secondaries would be most 

 likely to survive and transmit their structural peculiarities to their 

 descendants until the character became fixed and permanent. Such 

 development, of which the secondaries of the luna moth are an ex- 

 ample, is directly opposed to the common understanding that wings 

 should be as compact as possible without unnecessary appendages and 

 thus facilitate escape by rapid flight. If, therefore, it be deemed 

 reasonable and well proved that aggressive formation has developed 

 through its protective qualities, why is it not quite as reasonable to 

 assume that aggressive coloration has originated under similar circum- 

 stances and for a similar purpose, viz.: to divert the attention of a 

 pursuer to the conspicuous, vividly-colored, attractive-appearing sec- 

 ondaries, whereby the plainer, uncolored and unattractive but vital 

 parts escape injury. This result would undoubtedly be obtained 

 along the lines of natural experimental variation and varietal produc- 

 tion, those individuals having brighter, more striking, or more attrac- 

 tive-appearing secondaries being most likely to escape for the reason 

 that the attention of an enemy would ordinarily be diverted to these 

 showy but non-vital portions, and, as in the case of the luna moth and 

 other species with tailed secondaries, the individuals thus escaping 

 would be enabled to propagate and so bequeath their excess of color- 

 ation for fuller development. In the course of a long series of gener- 

 ations a constant elimination of the duller-hued individuals as being 

 the first captured and an equal survival from capture of the brighter 

 forms would inevitably tend to the abnormal development of highly 

 colored secondaries such as we find in the members of the genus Cato- 

 cala to-day, and will, I think, be accepted as a reasonable solution of 

 the origin of the extraordinary and apparently inexplicable departure 

 in coloration of the members of this genus from those of kindred gen- 

 era. The fact that there are now so many species, all variant in color 

 and maculation by bands or stripes, works no contradiction to this 

 theory. Granted that in the far distant past there was a primitive 

 ancestor in whose secondaries slight suggestions of bands might ap- 

 pear, it is easy along the lines of development to obtain more pro- 

 nounced variations, and the several species are simply the variant 

 forms which always arise under favorable or unfavorable environ- 



