MELANIN COLOR FORMATION. 34! 



4. The result of the union is a blend ; /. e., an oxidizing 

 power intermediate to that of the two gam'etes. 



Numbers I and 2 represent colors at points of fairly fixed color 

 equilibrium, as proved by the fact that individuals, varieties and 

 species tend to stop color formation at those points ; and most of 

 the offspring of such hybrids may reasonably be expected to 

 breed true with reference to this character, because of such stable 

 equilibrium. Categories 3 and 4 often represent, on the other 

 hand, colors at points of unfixed equilibrium ; stages in the oxi- 

 dation of tyrosin are not easily held at these points ; that such 

 points of unstable equilibrium arise in the chemical building of 

 melanin, as elsewhere, is practically certain ; this unstable condi- 

 tion is followed by an immediate tendency - - in the second (next) 

 generation usually --to shift to one or both of the stable points 

 represented by the male and female condition, or to a new point. 1 



The above considerations seem to be of far-reaching applica- 

 bility. They are, I think, rigorously consistent with what we 

 know of the oxidation process, and with the various facts of 

 melanogenesis ; whereas Mendelian interpretation is consistent 

 with neither. How much of the totality of color-inheritance is 

 thus brought under one point of view will be at once appreciated 

 by naturalists ; while in striking contrast is the very small frac- 

 tion of such inheritance that can be brought into the Mendelian 

 system, even with all its elaborations. 



In following out the implications of our conception of the state 

 in which these color characters exist in the germ, it may be said 

 that hybrid offspring possessing a color of easy, fixed equilibrium, 

 mated with similar forms may usually be expected to breed true 

 (that is, to continue this oxidizing power into their germ cells) 

 with respect to this character. If mated, however, with another 

 variety possessing some very different character, let us say size, 

 which is also in very stable, fixed equilibrium, it seems quite 



1 These four types give nothing of qualitativeness nor of discontinuity ; we have to 

 deal absolutely in these initial stages with quantity, degree or pitch of oxidation 

 power, and the gaps which we find in the end-result of the development of the color 

 characters are but the cumulative, final expressions of different degrees of oxidation 

 power, and of the fact that certain stages of oxidation are more stable in firmer 

 equilibrium than others. 



