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THE AMERICAN NATURALIST [Vol. L 



cessation of natural selection in the absence of sufficient models 

 to familiarize the hypothetical enemy with the several warning 

 color patterns of the models. On the mainland, however, any 

 of the aberrant intermediates that might be produced by inter- 

 breeding of the different varieties of the polymorphic species 

 would meet an enemy having constant experience with the warn- 

 ing colors of the different models, and tend to be eliminated. 

 The enemy, in other words, would avoid the perfect mimics, 

 while aberrant individuals suggesting two models at once pre- 

 sumably would be attacked and eaten. This interesting case de- 

 serves thorough investigation. 



The author makes a faux pas when he says regarding Seconal 

 variations in butterflies, due to "changes in the conditions of 

 later larval and earlier pupal life ' ' : 



In no ease are they known to be inherited, and in no case consequently 

 could variation of this nature play any part in evolutionary change. 

 In the example cited (Araschnia levana-prorsa) , which pre- 

 sents two color patterns alternately through the year, it is 

 obvious that both patterns are inherited. The environment in- 

 deed decides which shall appear, but the hereditary basis common 

 to both seasonal types is no less real than that of any butterfly 

 of seasonally uniform pattern. Although the seasonal color 

 patterns of A. levana and prorsa apparently can not behave as 

 Mendelian allelomorphs to one another as do the color patterns 

 of other non-seasonal polymorphic insects, they are by no means 

 outside the pale of Mendelian heredity. It is not too much to 

 expect that future studies will disclose colors or color patterns 

 allelomorphic to A. levana-prorsa' 's shifting coloration. The re- 

 viewer would not, with Professor Punnett, rule seasonal varia- 

 tion entirely out of court as possible stages in "the develop- 

 ment of a mimetic likeness" or, rather, in the evolution of the 

 remarkable likenesses, alleged to be mimetic, which this book 

 brings so well to our attention. 



The author is so strongly influenced by the idea that minute 

 variations are fluctuations always controlled by the environ- 

 ment rather than by the internal conditions that result in he- 

 redity that he treads upon uncertain ground in discussing an ex- 

 ample of local variation cited by Poulton. 9 A small white spot 

 on the wing of Danais chrysippus varies in size locally from a 

 conspicuous marking, in China, to a faint dot tending to dis- 

 » Bedrock, 1913, p. 300. Cited by Punnett. 



