No. 632] SHORTER ARTICLES AND DISCUSSION 



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THE INHERITANCE OF CONGENITAL CATARACT IN 

 CATTLE 1 



Cataract in mammals may be due to environmental causes, or 

 it may be hereditary. The mode of inheritance has been debated. 

 In the case of man Bateson (1) and Davenport (2) regarded 

 cataract as a dominant Mendelian character, while Jones and 

 Mason (3) in an analysis of human pedigrees collected by Har- 

 mon (4) concluded that cataract is probably a simple recessive. 

 Danforth (5) raised some pertinent objections to this latter 

 hypothesis, and Jones and Mason (6) later admitted the validity 

 of some of these objections. There are a number of elements in 

 this analysis of human pedigrees which are no doubt perplexing, 

 but the preponderance of evidence seems to favor the hypothesis 

 that cataract in man is a Mendelian recessive. 2 Hereditary cat- 



i Paper No. 10 from the Laboratory of Genetics, Illinois Agricultural 

 Experiment Station. 



calculated series. While there can be little doubt but that the observed 



expect the values of P to fluctuate around 0.5. Their results would there- 

 fore be interpreted as consistent with their theory, if their method were 

 correct. By using the method adopted by Jones and Mason, one might 

 nevertheless obtain a better (?) fit in this case and thus a more satisfactory 



than the^ series of cataractous. Ill any monohybrid ratio, the deviation of 



of larger calculated values for normals, then Xs will be perceptibly smaller 

 and P larger (P = 0.71 in this case). This procedure would be somewhat 

 comparable to stating that in a single toss of 8 coins, 5 heads are more 

 likely to appear than 3 tails, or in a single throw of n coins (n-p) heads 



