Bowditch: Red-Green Color-Blindness 

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♦ I s 71 1 » 9 



COLOR-BLINDNESS IN ALLIED FAMILIES 

 Color-blind individuals are designated by black; carriers by stripes; carriers according to 

 theory by shading; normal color-vision by N; and those about whom nothing is known by white. 

 Normal members of the family are not shown in the chart. III. 6 and III. 8 married sisters of 

 III.l in family I, a curious coincidence of three members of one family marrying consorts of 

 color-blind stock. (Fig. 21.) 



III. 6 and III. 8 married sisters, 

 who were the sisters of III.l in Family 

 1. We thus have the curious coinci- 

 dence of three members of one family 

 marrying consorts of color-blind stock. 



III. 6 had five daughters and one 

 son. All five daughters must, accord- 

 ing to the rule, be carriers, but two are 

 without children and one has a son 

 with normal vision and a daughter who 

 has no sons; so that the defect is trans- 

 missable (to date) only through two 

 daughters, IV. 5 and 6. 



IV. 5 has two children, both sons ; one 

 has normal vision; the other, V. 8, is 

 color-blind and has had no children. 



IV. 6 has six children, three sons and 

 three daughters. All three sons are 

 color-blind, V. 9, 10 and 11; of these 

 one is unmarried, one has two daughters 

 VI. 7 and 8, and the other has one, 

 VI. 9; these three granddaughters of 

 IV. 6 are still in their childhood, and 

 must be looked upon as carriers. 

 IV. 6 has, as was stated, three daugh- 

 ters who are potential carriers; one 

 is unmarried, but the other two have 

 respectively four and two sons, all 

 with normal vision. 



III. 8 had two sons and two daugh- 

 ters. One daughter died unmarried, 

 but the other, who must be looked 



upon as a carrier, IV. 7, had a son with 

 normal vision, and a daughter who has 

 had three sons, two of whom have nor- 

 mal vision and the third is too young 

 to be tested. 



To summarize: Family 2 starts with 

 a color-blind woman (II. 6) and the 

 rule of transmission is followed in that 

 it occurs in two sons (and, for all that is 

 known to the contrary, in the third as 

 well), thence descending through fe- 

 males to males; but in this family we 

 have no instances, as in the first family, 

 of transmission through two female 

 generations before it reappears in a male. 



Family 3 has a short chart. II. 8 

 died in 1891 and his daughter, III. 9 

 is now living at the age of eighty-one. I 

 rely upon her opinion for marking her 

 father as having normal color- vision, 

 for it seems as though such a defect 

 could hardly have been unknown to 

 her. She had two sons, one with nor- 

 mal vision, the other color blind, IV. 9; 

 he has no children. III. 9 is therefore 

 a carrier, and it appears safe to say 

 that the defect came to her through her 

 mother, a Virginian, whose family I 

 have been unable to trace, owing, 

 probably, to the destruction of the 

 records in Petersburgh during the Civil 

 War. 



