190 HALFDAN BRYN 



d) Gray parents and blue parents will have either only gray 

 children, or gray children and blue children in equal numbers. 



e) If one of the parents has gray eyes and the other brown ones 

 all their children will have either brown eyes (if the brown 

 parent is a homozygote) or 50 per cent of them will have brown 

 eyes and 50 per cent will have gray eyes, or 50 per cent will 

 have brown eyes, 25 per cent gray eyes and 25 per cent 

 blue eyes. 



It seems to me that these conclusions are very audacious. First, 

 the material is very small. Secondly, they have been collected by laity. 

 Further, their classification of the eye types is very vague, which is 

 also acknowledged. In the fourth place, their conclusions are not 

 correct. The fact is that cases where parents with plain blue eyes are 

 able to have children with brown eyes are recorded. 



But as this is at variance with the opinion held by the authors 

 they take for granted that such cases are due to mistakes made by the 

 observers. If the conclusions drawn by these investigators were cor- 

 rect they would of course be of great consequence in cases of paternity. 

 If a child for instance has brown eyes when the mother has plain 

 blue eyes, it should be out of the question that the father should have 

 blue eyes. This is not, however, the case according to my researches. 

 I have therefore found it of interest to take up the question in this 

 review. 



In »Proceedings of the Royal society» for 1908 there is a treatise 

 on the same subject by Professor C. C. Hurst entitled »On the Inheri- 

 tance of Eye-colour in Man». He has the same type-division as I 

 have employed in the following treatise, viz. simplex-types and 

 duplex-types. He arrives at the following conclusions: 1) If both pa- 

 rents are »simplex »-types, they will only have »simplex» offspring. 

 2)If both parents are »duplex »-types, they will have a) either only 

 duplex» offspring, or b) duplex offspring and simplex offspring in 

 the proportion 3:1. 3) In the case, where one of the parents is a 

 duplex-type and the other a simplex-type, their offspring will either 

 a) be duplex-types, b) or duplex-types and simplex-types in propor- 

 tion 1 : 1. 



My own results confirm in all essentials the correctness of his 

 assertions regarding points 2 and 3, but not as regards point 1. 



In table 1 a and b I have placed all the couples of parents who 

 have »simple» eyes. As will be seen, I have found 30 couples with 99 

 children in all belonging in this group. 26 of these couples had 



