ence to the males endowed with them, over those that are ' 

 less "attractive." These exceedingly romantic ideas have 

 been often and deservedly repudiated, e. g., even by Wal- 

 lace only a short time after their first appearance. Eimer 

 really does them too much honor when he again under- 

 takes, even with a certain amount of respect, a thorough 

 refutation of them, "as in every regard unfounded." It is 

 of primary importance to note here, that in the case of di- 

 morphism of the sexes abrupt modifications occur in con- 

 nection with unilateral heredity. "It is impossible for sex- 

 ual selection to produce a change of design and color, 

 which results in the sudden kaleidoscopic formation of 

 wholly different designs, as we find actually taking place 

 through the action of artificial heat and cold and other 

 factors in nature." 



This brings us to a brief consideration of the answer, 

 which Eimer proposes to give to the question of the real 

 causes of the formation of species among butterflies. A 

 precise and clear statement of this important part of 

 Elmer's theory of Descent, is contained in the following 

 extracts: "The transformation of organisms is primarily 

 conditioned by the action of immediate external influences 

 en the organisms. The same causes, which produce indi- 

 vidual growth, especially climate and nourishment, also 

 produce the organic growth of organisms, that is, trans- 

 mutation, which is but a continuation in the progeny of in- 

 dividual growth, through the transmission of the charac- 

 teristics acquired during the lifetime of the individual. 



81 



