PHYSICAL CHARACTERS IN MAN 117 



of whom had the defect. Photographs are given, 

 and a chart indicating that the character is a 

 Mendehan dominant. 



Nyctalopia or day-bhndness is also said to be 

 hereditary. Sedgwick (1861) cites a case of moment- 

 ary blindness after bending their heads in a father 

 and two sons. He also refers to the Le Compte 



Q X % Blind at 35 

 n X % Blind at 19 



1 



4 4 A 6 i 



bl.l3 bl.13 d-2 age 13 age 3 age I 



Fig. 21. — Female Sex-Linked Blindness. 



family, in which thirty-seven children and grand- 

 children became blind, like the grandfather, at the 

 age of seventeen or eighteen years. 



Two interesting, because contrasted, pedigrees of 

 amaurosis or hereditar}^ blindness are given by 

 Sedgwdck (1863). In the first (Fig. 21) the condition 



i * i i ii 6 6 6 



Fig. 22. — Male Sex-Linked Blindness. 



is apparently confined to the females, wdio go blind 

 before middle age. In the second the same con- 

 dition is confined to the males and skips a generation 

 in inheritance (Fig. 22). 



Several pedigrees of sex-linked inheritance of excep- 

 tional interest are described or cited b}^ Sedgwick 

 (1861). One of them is a family with ichthyosis 



