No. 595] SHORTER ARTICLES AND DISCUSSION 447 



reached maturity and produced one or more normal offspring, 

 thus proving on the assumption that cataract is recessive, that 

 his consort was either NN or Nn. Instead of finding, as we 

 should expect on the assumption that cataract is a recessive, that 

 only 3 or 4 (1:30) of these individuals would find an Nn mate 

 and therefore be capable of giving some affected children, what 

 we really do find is that of these 96 families, 83 have produced 

 cataractous children— 86 per cent. It is significant, incidentally, 

 that of the remaining 13, ten are families of three children or 

 less. A more striking refutation of the assumption could hardly § 

 be found. 



In regard to the second point we find that there are 47 normal 

 individuals in the same F 1 generation from the supposedly Nn 

 X nn matings who have also come to maturity and produced chil- 

 dren. In 42 of these families only normal children have resulted. 

 In 10 per cent, of such families, however, one or more cataractous 

 children have been produced. But the relation between 10 per 

 cent, on the one hand and 86 per cent, on the other is very far 

 from being the relation of one to two. 9 



These considerations based on the results from such matings 

 as are included in category B, and the F 2 descendants of such 

 matings, furnish convincing evidence that congenital cataract is 

 not a Mendelian recessive. 



Finally as to the last point, which concerns category C, we can 

 agree with the authors when they say : 



The ( 



rigs of £ 



by abnormal. Families of this kind should have only aDnormai 

 dren. Only three such matings are available. 

 I find two of these, but have searched the charts in vain for 

 third which must be an error or inadvertently drawn from 

 side sources. This really is immaterial since it would req 

 many such cases to prove the hypothesis, where a single bona 

 ease in which two affected individuals produce normal offsp 

 is sufficient to overthrow it. One of the three cases cited is s 



