PIGMENTATION IN OLD AMERICANS HRDLICKA. 463 



As in the skin and hair, so here again there are no lines of demar- 

 cation between the various shades, and we must make a somewhat 

 arbitrary classification. In this we may recognize to start with two 

 great groups, the pure eyes and the mixed. The pure in their turn 

 are capable of three subdivisions, the browns, the blues, and the lights 

 other than blue (gray, greenish) ; and the browns and blues are 

 further subdivisible each into the dark (or deep), medium and light. 

 Intermediary tinges occur appearing different under varying condi- 

 tions of light, health, and mental state, and can be classified only with 

 difficulty. 



The "mixed" eye is strictly speaking a misnomer. It does not 

 mean an eye with a mixture of any two distinct pigments, but an 

 eye, resulting from a mixture of a brown-eyed with a lighter parent, 

 in which the parental conditions are not well blended. If the eyes of 

 the parents are different, the eyes of some of the progeny may show a 

 darker or lighter blend of the parental colors ; the eyes of some may 

 show one or the other parental shade dominating with the other 

 in recession ; but the eyes of most of the children will bear traces of 

 the mixture in an unequal distribution of the pigment derived from 

 the darker parent. 11 It is these last eyes alone that the observer can 

 designate as " mixed." 



The " mixtures " are of many kinds, but they are all characterized 

 by some imperfection in the distribution of the brown. This may 

 occur as a narrower or broader ring about the pupil ; as a greater or 

 lesser dispersion of brown spots, with an aggregation about the 

 pupil ; in the form of brown patches or stains of color over the iris, 

 with lighter regions; and rarely in the form of a single brown seg- 

 ment radiating from the pupil to the periphery of the iris. 



From the above it will be seen that the only rational classifica- 

 tion of eye color can be about as follows : 



EYE COLORS. 



(Largely) [Light. 



Depigmented, pure Blues j Medium. 



[Deep. 

 Gray. 



Greenish. 



Grayish-blue. 



Greenish-blue. 



[Light. 



Pigmented Brown JMedium. 



[Dark. 

 Black, or near black. 

 Mixed Light brown . . . 1 with ring8; gpotS; patc hes, areas, 



Gray t stains, or segments of brown. 



Greenish or bluej 



u The laws of heredity in this connection are still under investigation. See Davenport 

 (C. B.)— Heredity of Eye-Color in Man. Science, 1907, XXVI, 589; Hurst (C. C.)— On 

 the Inheritance of Eye-Color in Man. Proc. R. Soc, 1908, SO :S ; Boas (Helene M.) — In- 

 heritance of Eye-Color in Man. Am. J. Phys. Anthrop., 1919, II, 15-20. 



