188 THE AMERICAN NATURALIST [Vol. L 



upon the bodies) of the mimics. Dried specimens of models 

 and mimics are likely to be confused, but not the living butter- 

 flies. 



Freyer's breeding experiments bring out the fact that a 

 simple Mendelian relation exists between the three varieties of 

 female in P. polytes, the males of which, though phenotypically 

 alike, correspond genotypically to the three kinds of female. Of 

 these three the one resembling the male ("non-mimetic") is reces- 

 sive to the mimetic forms, lacking a factor, X, possessed either 

 in simplex or duplex condition by the "mimetic" females. The 

 male likewise is latently either xx, XX, or Xx, as the case may 

 be, but retains a uniform appearance in all cases owing to the 

 presence of an inhibitor factor for which he is heterozygous 

 (Ii), the female being recessive (ii). The male, unlike other 

 Lepidoptera, so far as they have been investigated, is also sup- 

 posd to be heterozygous for a sex factor which we may for brev- 

 ity call M, responsible for maleness, with which the inhibitor 

 factor is completely coupled, so that the male-producing sperms 

 (MI) always contain the inhibitor factor, the female-producing 

 always lack it (mi). 



The two mimetic varieties of female are differentiated from 

 each other by the presence or absence of another factor, Y, 

 which acts merely as a modifier of the factor X when that is 

 present, and transforms the aristoloehige-like female (XXyy or 

 Xxyy) into the hector-like (XXYY, XXYy, XxYY, or XxYy). 

 This color modifier, responsible for intensifying and extending 

 the red markings, is supposed to occur in either homozygous or 

 heterozygous condition, or to be absent (recessive) in the male- 

 like form of female and also in each biotype of the male, though 

 when present without X, or in the presence of I, it has no visible 

 effect. Thus there are 9 biotypes of males and 3 of male-like 

 females, all phenotypically alike. Referring to Poulton 's theory 

 of the gradual evolution by natural selection of the male-like 

 type of female into the aristolochiffi-like, and subsequently into 

 the hector-like, Punnett argues that crossing the hector-like 

 (double dominant) with the male-like (double recessive) germ 

 plasms and inbreeding should show the hypothetical intermediates 

 postulated by Poulton, but no such intermediates have appeared 

 in the breeding experiments. 



Freyer's random sampling of the population of polytes gave 

 49 of the two mimetic females to 40 of the male-like coloration, 

 or roughly 5 dominants to 4 recessives, a proportion indicating 



