THE INHERITANCE OF FAMILY TRAITS Ul 



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kfo 



b|6 ^ ^ 



Fig. 88. — Ideal scheme, showing method of inheritance of color blindness. 

 Tj^ically it appears in sons only of simplex females, represented by a heavy 

 ring. The mating II, 5-6, is rare and has not been observed. The nature of 

 III, 11, is also doubtful. 



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more thanl 



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Fig. 89. — A remarkable and exceptional pedigree of color blindness. The 

 fraternity, II, 1-5 (which comprises the grandfather, his brothers, and his 

 3 sisters), were said all to be color blind. The grandmother, II, 6, had the 

 normal color sense but had an affected brother. The entire fraternity, III, 1-5, 

 including 4 females, has impaired color perception. Details are given about 

 III, 5, as foUows: She is about 50 years old, a physician's wife, and a test 

 shows complete confusion of dark green, dark red and brown. While Hghter 

 tints are better distinguished, rose and blue are confounded. The sons show 

 exactly the same conditions. Reber, 1895. 



ters may inherit color blindness from fathers. At least such 

 is the history given by Reber (1895), Fig. 89; an exceptional 

 history that is not entirely without precedent. In the case 

 of these exceptional families a color blind parent may have 

 color blind offspring of either sex. 

 0. Myopia. — That the shape of the eyeball is largely 



