FIVE GENERATIONS OF CONGENITAL STATIONARY 

 NIGHT-BLINDNESS IN AN AMERICAN FAMILY. 



By H. H. NEWMAN. 



{Fi'om the Hull Zoological Laboratory, University of Chicago.) 



In his book Mendel's Principles of Heredity, BatesoD, discussing 

 the laws of sex-limited inlieritaiicc in man, says that " the only one of 

 the notoriously sex-limited conditions which is available for testing the 

 rules is colour-blintiness. Haemo2:)hilia and Gowers' disease are too 

 fatal and night-blindness is too rare and too little known." It is the 

 purpose of the present paper to add a chapter to the present meagre 

 literature on the inheritance oF night-blindness'. The data herewith 

 presented were obtained in collaboration with Miss Elizabeth L. Brown, 

 who has had exceptional opportunities for getting at the facts since she 

 is a member of the affected family and has seen and tested the majority 

 of her living relatives. Those whom she has been unable to observe 

 have freely communicated the facts to her. I have been in correspond- 

 ence with Miss Brown for considerably over a year and have directed 

 her investigations. Every effort has been made to eliminate all sources 

 of error and to obtain all information that might be of value. There is. 

 still some doubt as to the exact character of the defects associated with 

 night-blindness, but we can vouch for the accuracy of the pedigree as 

 given in the diagram in so far as the major defect, night-blindness, is 

 concerned. Errors have been eliminated from the pedigree largely 

 through the use of a questionnaire suggested by Mr Nettleship, who 

 has been kind enough to express a personal interest in the progress of 

 the investigation. 



' A very recent paper by Nettleship has just come to my attention in which a case of 

 night-bUndness similar to that here dealt with is discussed. The paper is : "A Pedigree 

 of Congenital Night-Bliiidness with Myopia." Ophth. Soc. Trans. Vol. xxxii. 1912. 



