230 



The Journal of Heredity 



D(D) l(d) r(d) r(l) l(iJ d(l) d(d) l(d) R(d) r(l) l(0 d(0 



HOW HAIR AND EYE COLOR ARE INHERITED 



vSolid line — ]K'T cent whieh those of each combination of hair and eyes color form of the 

 relatives of the color combinations at the top of the figures. Broken line — per cent of 

 those of each color combination form of the husbands and wives of the color ccmbination 

 at the toj). D — dark hair, L — light hair, R — red, auburn or yellow hafr, (D) — dark eves, 

 (Lj— light eyes. (Fig. 17) 



rcspcjiisiblc as in the case of traits which 

 are pecuHar to a few famihes. As 

 noted, hair with sufficient suggestion 

 of red to he called auburn is found 

 in 8.8% of a random Wisconsin 

 student pojnilation. If red were reces- 

 sive this would nuan tliat almost half 

 the remaining population would be 

 heterozygous. 'ihe situation is even 

 more diflicuh to analyze in the case of 

 the (hfTerences between dark anfl Hght 

 l\'iir or eyes, brunette or l)lond coni- 

 l)lexi()n, etc. Again, none i)i tl'.ese com- 

 mon variations are obviously discon- 

 tinuous. .\!l grades of com])lexion be- 

 tween dark brunette and the fairest 

 bionfj are common in persons of liritish 

 descent. .All variations in hair color 

 between intense black throuLdi brown 



to flaxen and from black through the 

 reddish blacks and aubiu-ns to clear 

 red ma\- be fotmd in such a ])opidation. 



EVli COLOR 



Kye color shows more discontinuity 

 than hair and skin color as there is 

 rather of an abru])t transition between 

 brown and eyes which show a distinctly 

 greenish or bluish tint, (ialton" con- 

 sidered human eye color a good ex- 

 ample of discontinuous hereditv. Never- 

 theless it appears that the discontinuity 

 is superficial even here, b've color is 

 due to ])igment deposited on both sides 

 of the iris. 1 here is also pigment in 

 other parts of the eye, inchiding the 

 ri'tina. In a series of eves showing 

 gradual rt'duction in i)ignu'mation. tin- 



"Gallon. I".. ]HW. "Xatiiral inheritance." 



