200 



THE AMERICAN NATURALIST [Vol. XLIII 



of light and dark haired offspring. Actually, the lighter 

 colors are in excess— a result again doubtless due to the 



Table VI. Distribution of Hair Color in the Offspring when One 

 Parent has Black Hair and the Other Brown Hair 



relative immaturity of the children as compared with their 

 parents. 



Assuming, as in the discussion of Table V, that the 

 blacks are heterozygous (except in the Ste-D family) we 

 should expect an equality of dark and light haired off- 

 spring modified by preponderance of the lighter type 

 owing to the immaturity of the average of the offspring. 

 Actually, with brown hair and lighter there are 41 chil- 

 dren as opposed to 7 (Ste-D omitted) kith either black or 

 dark brown hair. When we compare the proportion of the 

 children having hair brown or darker in this Table (60 

 per cent.), with that in Table V (36 per cent.) we realize 

 •how much more frequent the darker classes have become 

 with the increased darkness in the hair of the second 

 parent. 



On account of the impossibility of drawing the line be- 

 tween the dark and the light shades of hair and on account 



