RED-GREEN COLOR-BLINDNESS IN 

 THREE ALLIED FAMILIES 



Harold Bowditch, M. D. 

 Boston, Mass. 



rp, 



^HIS small piece of research was 

 JL undertaken with the purpose of 

 discovery, if possible, the source of 

 red-green color-blindness in the family 

 numbered 1 in the accompanying chart. 

 The quest was unsuccessful ; but in its 

 pursuit enough cases of color-blindness 

 were found to make it seem worth 

 while to put the facts on record. I 

 wish to take this opportunity to 

 thank Prof. Leon J. Cole of the Llniver- 

 sity of Wisconsin, Prof. Edwin G. 

 Conklin of Princeton University, and 

 especially Dr. Howard J. Banker of the 

 Eugenics Record office at Cold Spring 

 Harbor, New York, for their kind sug- 

 gestions and criticisms, as well as nu- 

 merous members of the families under 

 consideration for their courtesy in 

 answering questions. 



In the accompanying chart I have 

 designated males by squares and fe- 

 males by circles; color-blind individuals 

 by black; carriers of color-blindness by 

 stripes; carriers according to theory by 

 shading, normal color-vision by N, 

 individuals about whose vision nothing 

 is known by white, and suspected color- 

 blindness by a query. 



It will be convenient to begin by 

 considering the case of Family 1, 

 Generation IV, individual No. 1, 

 whom, for brevity, we shall call IV. L 



IV. 1 , was a professor of physiology 

 and an authority on the physiology of 

 vision; he wrote the section on this 

 subject in the American Text Book of 

 Physiology (1896). He was red-green 

 color-blind and was much interested in 

 the subject but I have been unable to 

 find out that he knew how the defect 

 descended to him. He had two broth- 

 ers with normal color-vision, and three 

 sisters, of whom two died unmarried 

 and the third is represented on the 

 chart as IV. 2. IV. 1 had two sons, 

 both with normal color-vision, and five 

 daughters; of these, two have no sons; 



one, V. 1, has three daughters and 

 one son, VI. L who is color-blind, and 

 the two others, V. 2 and V. 3, twins, 

 have each two color-blind sons, VI. 2 

 and 3, and VI. 4 and 5 respectiv^ely. 

 V. 2 has in addition one daughter and 

 three sons whose color-vision is normal. 



IV. 2 had one daughter and three 

 sons; the daughter has a daughter, and 

 of the three sons, two are color-blind, 

 V. 4 and 5. V. 4 has a daughter, VI. 6. 



IV. 1 must, according to the rule, 

 have derived the defect from his 

 mother. III. 2; and as it is known that 

 her husband. III. 1, had normal color- 

 vision, it is clear that IV. 2, also derived 

 her color-blind carrying capacity not 

 from him but from the mother. III. 2. 



IV. 4, who was first cousin to IV. 1 

 and 2, was color-blind; his brother, 

 however, is a successful painter; there 

 are two unmarried sisters; and a mar- 

 ried sister, IV. 3, who has had two 

 daughters and a son with normal color- 

 vision, and two sons, V. 6 and 7, who 

 are color-blind. IV. 4, like IV. 1, 

 indicates that his mother. III. 3, was a 

 carrier, and her husband having had 

 normal color-vision, it is evident that 

 V. 6 and 7 get their defect through 

 their mother's mother. III. 3. 



III. 2 and III. 3 were sisters; they 

 had a brother and two sisters who died 

 single, and had the brother been color- 

 blind it would have been known to 

 IV. 1, who lived near his uncle and 

 saw much of him. Had this been so, 

 we might safely have attributed the 

 defect to the mother, II. 2, but as it is 

 we can say only that the sisters III. 2 

 and 3 got the defect either from a 

 color-blind father, II. 1, or from a 

 carrier mother, II. 2. From which of 

 these it comes is the point I have 

 failed to elucidate. 



II. 1 was a lawyer, well known in 

 Salem and Boston, and he lived 

 until 1848, eight years after the birth 



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