114 HEREDITY IN RELATION TO EUGENICS 



dren at from 55 to 40; and a mother is affected in one eye at 

 60 and the other eye at 81, while her 3 children are affected at 

 60. In one family strain, Von Graef e noticed an unusually long 



^~^ 



Fig. 80. — Pedigree of family with glaucoma, showing simple dominance 

 of the trait. In I, 4, the disease appeared at 40 years of age; in II, 2, at 28; 

 in II, 4, at 25; in generation III, at 28 to 17 years — an extraordinarily early 

 age. Howe, 1887. 



prodromal stage (10 to 15 yrs.), before the fully developed 

 attack. This is one of the special family strains. 



Glaucoma is said to have various inciting causes. The 

 tjT^e that follows a characteristic inflammation shows the 



[KSoip 



5E^ii 



a 9 6 



Fig. 81. — Pedigree of family with glaucoma, percentage of incidence of 

 disease small, owing perhaps to early deaths (?). In the first generation the 

 disease began at 71 years, in the second at 40; in the third at between 25 and 

 30 years. Nettleship. 



best evidence of heredity. A pedigree or two will illustrate 

 the method of its inheritance (Figs. 80, 81). 



The eugenic teaching is rendered more difficult by the 

 fact that glaucoma usually first appears toward the end of 

 the reproductive period. But certainly affected persons 



