THE 



AMERICAN NATURALIST 



Vol. XLIV December, 1910 No. 528 



HEBEDITY OF SKIN PIGMENT IN MAN. II 

 GERTRUDE C. DAVENPORT and CHARLES B. DAVENPORT 

 Carnegie Institution or Washington, Station of Experimental 

 Evolution, Cold Spring Harbor, N. Y. 



E. INHEEITANCE OF ALBINISM 



Albinism is the absence of pigmentation through lack 

 of either, or both, the chromogen and the oxidizing fer- 

 ment. The condition occurs widespread among animals 

 and plants. In man it is rather rare, probably not occur- 

 ring (if one may hazard a mere guess) in the population 

 of the United States, as a whole, in more than in one 

 case in 10,000 people. 



Of true albinism in man there are all degrees. Aside 

 from the piebald condition occasionally found in colored 

 persons there are various grades of uniform depigmen- 

 tation — hair color varying from light yellow to pure 

 white ; irides varying from pale blue to absence of blue, 

 and pupils varying in the intensity of the pink color. 

 Indeed, there is abundant testimony that persons born 

 as albinos may acquire a slight pigmentation. Such a 

 case was cited by Dr. H. B. Young (1905) from Illinois. 

 Albino cats also vary in the pinkish glow of the retina. 



Despite variations in the completeness of depigmenta- 

 tion albinism can usually be clearly distinguished, at 

 least in its more marked grades, and so we can study its 

 inheritance. The cases given below were mostly col- 

 705 



