16 SOME POSSIBLE BEARINGS OF GENETICS ON PATHOLOGY 



Since this statement has recently been disputed by Buchanan, from 

 an entirely wrong interpretation of Mendel's principles, I should 

 like to point out that on the Mendelian assumption of two pairs 



Mating of blood group AaBb to same AaBb 



•g£ s 



AB 



a 



B Ab 



a 



b 



bperm 



AB 



lB 



AB 

 AB 



Ab 



ai 



a B 



a B 



m 



a 



B 



a 



m 



n 



a 



a 



B 



IE 



a b 

 a b 



Fig. 8. Representing the kinds of individuals expected when an individ- 

 ual of the blood group type AaBb marries an individual of the same blood 

 type, namely AaBb. Sixteen kinds of individuals are possible in the ratio of 

 <)■. 3- 3- I. These belong to four blood types, namely, class IV that contains 

 at least one A and one B; class II that contains at least one A but no B; 

 class III that contains at least one B but no A; and class I that contains 

 neither A nor B. 



of factors, all the known results are fully accounted for. If we 

 represent one pair of genes by A and a and the other pair by B 



