THE 



AMERICAN NATURALIST 



Vol. XLV August, 1911 No. 536 



A C< >MPARATIVE MICROSCOPIC STUDY OF THE 

 MELANIN CONTENT OF PIGMENTED SKINS 

 WITH SPECIAL REFERENCE TO THE 

 QUESTION OF COLOR INHERIT- 

 ANCE AMONG MULATTOS 



PROFESSOR H. E. JORDAN 

 University of Virginia 



Introductory, with a Statement of Problems 

 Involved 



The comparative histologic study of pigmented skins 

 was undertaken with the hope of discovering evidence 

 that might throw more light on the problem of color 

 inheritance among the descendants of crosses between 

 whites and negroes. The primary point at issue, until 

 very recently, was whether human skin color in inherit- 

 ance conformed more closely to the alternative (Men- 

 delian), or the blended scheme; or perhaps to the ances- 

 tral (Galtonian) scheme. The studies of G. C. and C. 

 B. Davenport show conclusively that there is a measure 

 of segregation among the individuals of the third gen- 

 eration, hence a Mendelian-like inheritance. 



This study, suggested to me by the above-mentioned 

 investigators, is, consequently, more especially an at- 

 tempt to test, as critically as microscopic data will allow, 

 the theory of discrete unit characters in color inherit- 

 ance (discontinuity theory; segregation theory), as op- 

 posed to the theory of continuity of the pigment char- 

 acter with interruption of the pigmentation process at 

 449 



