No. 590] SHORTER ARTICLES AND DISCUSSION 125 



In the matings of normal by normal, there is, of course, no 

 opportunity for this error to influence the classification of the 

 parents, since abnormals, whether heterozygous or not, would 

 not come here. But with the children, the number with the re- 

 cessive character would be raised above the regular expectancy ; 

 a result which coincides with that in Table I. 



If with more matings of abnormal by abnormal it is found 

 that, with a few exceptions, only abnormal children are given, 

 the evidence that cataract is a recessive character rather than a 

 dominant will be fairly conclusive. It seems rather strange 

 that congenital cataract manifesting itself, as it does, in such 

 different ways, should be determined by a single unit factor. 

 These things, however, must be explained in the simplest pos- 

 sible manner ; an attempt to work it out with two or more factors 

 would introduce great complications, and be practically im- 

 possible with the data as they have been gathered heretofore. 

 The fact that a recessive character may not be recognized, for 

 it occurs in mass data in a greater proportion than would be 

 expected at first, should be noticed. Finally the approxima- 

 tion of the results obtained with those expected from the single 

 unit factor form the best reason for its acceptance. 



That certain geneticists should have laid down eugenic rules 

 based on the inheritance of this character as a dominant is, at 

 the very least, unfortunate. It is not only because of a mistake 

 in the method of inheritance, but such rules should never be 

 made until the exact hereditary processes are positively known, 

 since such practises are likely, not only to bring discredit upon 

 the science, but to injure people who endeavor to follow them in 

 the regulations of their lives. 



D. F. Jones, 

 S. L. Mason. 



Harvard University. 



BIBLIOGRAPHY 



1. Nettleship, E. On Heredity in the Various Forms of Cataract. Rep. 



Roy. Lond. Ophth. Hosp., XVI, 1905, p. 1. 



2. Harman, N. B. Treasury of Human Inheritance, Eugenic Laboratory 



Memoirs, XI, Part IV, Section XHIa. Dulau & Co. 1910. 



3. Davenport, C. B. Heredity in Relation to Eugenics. Holt, 1911. 



4. Apert, E. The Laws of Naudin-Mendel. The Journal of Heredity, 



Nov., 1914, 492-497. Translation from Eugenique, II, 5, 129 ff., 

 Mai, 1914. 



