No. 595] SHORTER ARTICLES AND DISCUSSION 445 



neither parent of the affected individual shows the defect (i e., 

 both are presumably heterozygous). These 44 pairs of parents 

 are recorded as having 320 children, of whom 77 are affected— 

 24 + per cent, as compared with an expectation of 25 per cent. 

 If the data on cataract were to yield results as close as this we 

 would be more disposed to credit the view that the character is 

 recessive. 



So far as the 31 families of category A are concerned it must 

 be admitted that absolute proof of the fallacy of the recessive 

 character view can not be furnished, but it will be apparent that 

 there is considerable evidence which not only fails to support 

 this view, but actually points decidedly against it. This fact, 

 taken in connection with the positive refutation which the data 

 in categories B and G supply, makes a very strong case against 

 the view that congenital cataract is a recessive character. 



In the second category (B) where one parent is allVrtc.l the 

 other normal, Jones and Mason remark that "the number of 

 affected children would be expected to be approximately the same 

 whether the character was inherited as a dominant or a recessive" 

 (p. 121). But it must be borne in mind that the offspring of a 

 recessive show the 1 : 1 ratio only when the mate is heterozygous, 

 and in their second table Jones and Mason assume that the par- 

 ents of the children in group B represent the cross "NnX nn." 

 The question is not raised as to the probability of the occurrence 

 of such matings nor does there seem to have been an attempt 

 made to trace the offspring from the normal and affected mem- 

 bers of the F 1 generation. In other words, the data of really 

 critical significance do not seem to have been considered. As it 

 stands, then, Table II seems to present no evidence either for or 

 against the above hypothesis, a point which the authors them- 

 selves recognize as the quotation indicates. 



Since the authors have not tabulated the data which would 

 seem to be of most significance, we may return^o Harman's orig- 

 inal charts assuming for purposes of the discussion that con- 

 genital cataract really is a recessive. On this assumption there 

 are two important conditions which we should expect to find ful- 

 filled. 



1. If congenital cataract were a recessive, a cataractous person 

 married to a normal should in most cases produce only normal 

 children. This will be apparent when it is recalled that con- 



