H. H. Newman 27 



now good evidence as to the condition of 23 sons of colour-blind men 

 and all are normal (besides 15 more said to be normal on less ceitain 

 authority). Such a fact is very significant." 



That colour-blindness is not the sole optic affection following this 

 interesting inheritance formula is shown in the present case where 

 night-blindness is seen to follow exactly the same course. 



Following the method adopted by Nettleship and others I shall first 

 give a pedigree showing the inheritance of night-blindness, dealing 

 with the less certain accompanying affections in connection with the 

 descriptions of individual cases. The five generations will be taken up 

 serially, beginning with the oldest, and each individual will be referred 

 to a number shown in the diagram. 



I, 1. Joel Bryan of North Carolina, a Quaker, probably of English 

 extraction. No definite information as to whether or not he was night- 

 blind. 



I, 2. Wife of Joel Bryan. No information obtainable concerning 

 her maiden name or antecedents. 



I, 3. Thomas W. Vause of North Carolina, a physician, a first 

 cousin (?) of Joel Bryan, but considerably younger than the latter. As 

 a young man Mr C. D. Uzzell carried on a considerable correspondence 

 with Dr Vause with reference to the night-blindness with which both 

 were affected. There is no doubt then that niglit-blindness was of 

 earlier origin than this generation. 



II, 1. Margaret Bryan Uzzell, daughter of Joel Bryan, is the only 

 issue of the latter that it has been possible to bring to light. Several 

 years after her marriage to Mr Uzzell in North Carolina she moved to 

 Texas and was the ancestor of the present Texas night-blind connection. 

 She had normal vision but transmitted night-blindness to three of her 

 four sons. There were in addition five normal daughters. 



II, 2. Mr Uzzell, husband of Margaret Bryan Uzzell, had normal 

 vision, as is testified by his son, Mr C. D. Uzzell. 



III, 1 — -11. Issue of II, 1 and 2. No other pregnancies known to 

 Mr C. D. Uzzell. 



1. J. C. Uzzell, dead, night-blind to the same extent as C. D. 

 Uzzell (5). He seems to have left no progeny. 



2. Mrs Haynie, dead. There is no record of night-blindness in her 

 or in her progeny. 



3. Mrs Bayers, dead. Normal and normal progeny. 



4. Mrs C. U. Carson, aet. (1912) about 77, normal vision and 

 normal progeny. 



