COLORATION IN POLISTES. 



Bv WiLHELMINE M. EnTKMAN. 



INTRODUCTION, 



This paper records the results of an inquiry into the nature and 

 probable causes of specific differentiation in the genus Polistes. Apart 

 from differences in size, the chai'acters used to separate the species are 

 based almost exclusively on color. Accordingly, this investigation 

 resolves itself into a stud}' of coloration in the genus. 



It would be superfluous to rehearse here at any length the various 

 theories which have been advanced to account for the origin of species ; 

 but, for the purpose of defining the various lines of investigation taken, 

 I will nevertheless revaew very briefly those most widely accepted. 

 Chief among these, as a matter of course, is the theory of Darwin that 

 species have arisen primarily by the selection of minute fortuitous 

 variations. To explain these variations we have on the one hand the 

 theories of Amphimixis and sexual selection, and opposed to these the 

 belief, first advanced by Lamarck, that characters are acquired during 

 the lifetime of the individual and accumulated by transmission to 

 succeeding representatives of the race. Less generally held, perhaps, 

 but gaining in credence, is the solution urged by Bateson, and main- 

 tained also by De Vries, that individual variations, from the first, tend 

 to be discontinuous and represent conditions of greatest chemical 

 stability for the organism, and related to this is Elmer's theory of 

 orthogenesis, which regards species as arising by the persistence, at 

 various stages, of certain combinations of characters, that, both in the 

 individual and the race, tend to unfold in a particular sequence. Finally, 

 I cite the theories of Henslow, who considered as most important, in 

 this connection, certain auto-adaptive or self-adapted varietal characters 

 which arise in direct response to changes in environment, and those of 

 Gulick and Romanes, who follow Wagner in regarding isolation of 

 various kinds as the primarj^ factor in the evolutionary process. 



The bearing of the foregoing resume is obvious. The theories here 

 cited were applied to the conditions actually observed in Polistes and 

 gave direction to the several lines of experimentation carried out. 



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