SHORTER ARTICLES AND DISCUSSION 



FURTHER REMARKS ON THE INHERITANCE OF 

 CONGENITAL CATARACT 



An article 1 by the writers in a previous number of this publi- 

 cation dealing with the inheritance of congenital cataract in a 

 statistical way has been rather severely arraigned by Danforth* 

 in a more recent issue. In our original paper we presented data 

 taken from genealogical tables published by Harman in the 

 " Treasury of Human Inheritance " which led us to believe — 



1. That congenital cataract could no longer be considered as a 

 single, dominant, unit character. 



2. That Davenport should be criticized for making eugenical 

 recommendations based on the inheritance of cataract as a domi- 

 nant character when the method of inheritance is not positively 

 known. 



3. That from the evidence at hand cataract could better be 

 considered as a single, recessive, unit character, reserving final 

 decision as to this point until more complete data should become 

 available. 



Danforth believes with us that congenital cataract can not be 

 considered as a simple, dominant character. Nevertheless he 

 tries to defend Davenport from "unjust" criticism while he 

 does not agree with him. It is upon the assumption of cataract 

 as a positive or dominant character that Davenport bases his 

 eugenical recommendation as follows: 



The usual method of inheritance is that of a positive character. Af- 

 fected individuals have either half or all of their offspring affected, 

 while two unaffected parents will probably not have defective offspring. 

 However, as cataract usually appears late in life it is not .always pos- 

 sible to predict whether the parent will become affected or not. 



The eugenic rule is this: If either parent has cataract at least half of 

 the offspring will have it also. If a person belongs to a strain that has 

 cataract but is free from it, advice must depend on the nature of the 

 cataract. If in the family strain cataract appears early, before the age 



i Jones, D. F., and Mason, S. L., "Inheritance of Congenital Cataract," 

 The American Naturalist, 50: 119-126, February, 1916. 



2 Danforth, C. H., "Inheritance of Congenital Cataract," The Ameri- 



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