MELANIN COLOR FORMATION. 319 



receive the attention which they deserve without such a setting. 

 I am, of course, rather confident of the correctness of the point 

 of view set forth. I am absolutely convinced that the facts here 

 presented will prove valuable assets to the student of develop- 

 ment and inheritance. 



There are three reasons why melanin color formation, better 

 than any other process or group of processes, may furnish the 

 starting point for certain inquiries and criticisms regarding the 

 way Mendelian inheritance is construed and described : 



1. Color characters have been more extensively studied and 

 described from the Mendelian standpoint than have any others. 

 A very considerable share of the color investigated all mam- 

 malian color, for example is due to melanin pigment. 



2. It was to recognize a fact in melanin color development that 

 Cuenot ('03) introduced the idea of presence and absence of a 

 character, or character determiner, etc.; an idea which is now 

 made by many workers to support practically the whole struc- 

 ture of Mendelian description and interpretation. Again, the 

 now rather elaborate terminology introduced by Castle is based 

 almost wholly upon the behavior of melanin colors. A few 

 paragraphs of the paper by Cuenot furnish practically all there 

 is of a tangible basis for representing cJiromogens, enzymes, and 

 activators in gametic formulae. 



3. There is already at hand a certain amount of definite chem- 

 ical knowledge, and some reasonably safe physiological informa- 

 tion, which can be brought to bear on some points of the color 

 philosophy of Mendelism. There is, moreover, something which 

 though apparently less substantial, is none the less important - 

 namely, the assurance of further, definite light from these same 

 sources. There can be no doubt that we can use biochemical 

 and physiological methods and data to give us what is now more 

 needed than all else, perhaps, in the study of evolution and de- 

 velopment namely, the intimate developmental history, and na- 

 ture of some one character ; I mean the proximate history, the 

 mechanics of what some would call the "late stages" of the 

 development, or the " differentiation " of a character. 



It may help to keep the reader oriented throughout this dis- 



