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THE AMERICAN NATURALIST [Vol. XLIV 



A. INTRODUCTION 

 In the modern discussions on heredity there are those 

 who, without undertaking experiments themselves, as- 

 sume an attitude of hostility to the work of the experi- 

 mental investigators of heredity and have taken a last 

 stand in the phenomena of inheritance of human skin 

 color. Pearson (1909), who has urged that the collection 

 of extensive statistics is a prerequisite of deductions in 

 the field of heredity, has actually published the non- 

 quantitative impressions of a medical correspondent in 

 the West Indies concerning the method of inheritance 

 of skin color in negro X white crosses and concludes that 

 "in view of the opinion" cited "the suggestion that skin 

 color 'mendelizes' should not be vaguely made." He 

 thinks his correspondent's "views" establish "the main 

 point" "that the segregation in the second generation 

 to pure white or black skins does not occur." On the 

 other hand, a writer in the Mendel Journal, No. 1, has 

 also a correspondent in the zone of intermingling whose 

 observations indicate partial, if not complete, segrega- 

 tion. Altogether the subject seems to deserve a more 

 extended, less biased treatment. 



B. ANATOMICAL KELATIONS AND KINDS OF 

 SKIN PIGMENT 

 The pigment of the skin, at least the melanic pigment 

 which alone concerns us here, has its basis in the fine 

 granules lying in the deeper layers of the stratum 

 mucosum of the skin. The granules themselves are of 

 mesodermal origin and the pigment cells — melanoblasts 

 — seem to penetrate from below into the mucosa. Ehr- 

 mann (1896, Taf. XI, Fig. 24; Taf. IX, Fig. 19) has fig- 

 ured these melanoblasts in sections of the skin, both of 

 brunets and of negroes. They are much the more abun- 

 dant in negroes. The anatomical facts are that black 

 skin pigment is made up of many discontinuous elements 

 —the pigment granules. But the mosaic is so fine that, 

 to the naked eye, the color is apparently uniform and a 



