PHYSICAL CHARACTERS IN MAN 45 



in albinotic eyes is shown to be absent or imperfect, 

 and this may be the chief cause of the imperfect vision 

 in such eyes. In the eyes of albinotic individuals 

 belonging to dark races the mesoblastic pigment 

 appears earlier and is found in much larger quantity 

 at time of birth than in European eyes. Chemical 

 examination indicates that there is more pigment in 

 the eyes of albinos of dark races than of white races. 

 This is in line with much evidence from mammals 

 of a close relation between density of coat colour and 

 of eye pigmentation. 



Recent studies of brown and blue eyes indicate 

 that they are not alw^ays a simple pair of Mendelian 

 characters as formerly supposed, but sex-linkage 

 and other complications may come in. Br^^n (1920) 

 collected statistics in Norw^ay and states that in four 

 out of thirty marriages tw^o blue-eyed parents had 

 some brown-eyed children. From these four mar- 

 riages there were ten children with brow^n eyes and 

 seventeen with blue. One or both grandparents, in 

 all cases, had brown eyes. Winge (1921), in a much 

 more extended studv, criticises these results and 

 concludes that such cases are exceedingly rare if the 

 parents have normal vision. By means of a question- 

 naire, Winge collected data of eye colour in about 

 1 ,400 children of natural history association members 

 in Denmark and their parents. The data obtained 

 were carefully sifted, and the results are given in the 

 table on p. 46. 



From the table it will be seen that, in addition to 

 the seven children with doubtfull}^ blue eyes from 

 blue-eyed parents, twelve children (belonging to eight 

 families) had brown pigment in their eyes. Further 

 information obtained from five of the families indi- 

 cates that the condition was due in two cases to 

 abnormalities in the eye. In another family of seven, 

 two of the daughters had some brown pigment in 



