4 HEREDITY OF SKIN COLOR IN NEGRO-WHITE CROSSES. 



times reveals the deception. We shall have occasion to call attention 

 to some of these cases where the putative father is not the real father. 



D. ONTOGENETIC DEVELOPMENT OF THE SKIN COLOR 



OF THE NEGRO. 



In making comparisons of skin color a certain difficulty is intro- 

 duced by the fact that the color of the skin is not constant throughout 

 life in the same individual. The variations due to the direct action of 

 the sun (tanning) were largely eliminated by making measurements 

 upon a covered part of the arm. This was possible inasmuch as both 

 children and adults in both Bermuda and Jamaica usually wear clothing. 



Variations due to age have to be carefully considered. It is pretty 

 generally agreed by accoucheurs, both in Africa and in the Southern 

 States, that the negro baby is nearly white at birth. Some of this 

 testimony may be cited. 



Pruner-Bey (i860, 1864) stated that it was sometimes impossible to 

 distinguish a new-bom negro from a new-bom white, by examining skin 

 color only. 



Simonot (1862), stationed at Senegal, says that the negroes of Yoloff de 

 Saint Louis are the blackest that he knows. At birth the infant of this race is of 

 a rose color lightly accentuated with a bistre tint, which is the representative 

 at this early age of the future pigmentation and enables one to distinguish 

 it from a European infant; but it is not always easy to distinguish it from 

 certain crosses .... After some hours have elapsed the rose tint is obliterated 

 and at the same time the bistre shade becomes more pronounced, approaching- 

 more and more to the black. . . . Only after several days has the skin ac- 

 quired a definitely black color and this grows darker until the end of the first 

 year at least and does not acquire its maximum intensity until puberty. The 

 color is acquired more promptly if the infant is exposed to the sunlight. 



Brodnax (1900), who has particularly attended to this matter in our 

 southern states, writes: "Twenty cases of new-bom negro infants have been 

 examined by me per year and I have never yet seen a dark-colored infant at 

 birth. They are of a tallowy white, while the white infant is of a clear, 

 bright pink. It makes no matter how black or white (mulatto) the parents 

 are, the scrotum and raphe are of a dark brown." 



Schiller-Tietz (1901) concludes, from the accounts of travelers and 

 sojourners in Africa, that the negro child is born, if not distinctly white, at 

 least of a clear color, and only after a longer or shorter time after birth acquires 

 the dark-brown color of its race. He adds : " The color is darker after eating, 

 at a higher temperature, during exercise, in consequence of psychical disturb- 

 ances (embarrassment, shame), and, in general, whenever the blood pressure 

 is increased in the skin capillaries." He concludes that the attainment of 

 full skin color, even in Africa, varies from 6 weeks to 3 years, but occasionally 

 takes only a few days. 



Studies by Thomson (1891) and others show that the formation of melanic 

 pigment has already begun at the base of the hairs in the fetus at the age of 

 S months. 



At the Memorial Hospital, Richmond, Va., a male child was ex- 

 amined 6 days after birth. His mother and father were both dark- 



