194 EVOLUTION AND GENETICS 



The Four Blood Groups and their Inheritance 



One of the most remarkable cases of heredity in 

 man is found in the so-called blood groups. As first 

 shown by Von Dungern and Hirschfeld in 1910 the 

 inheritance of the four blood groups conforms to 



I 



II 



III 



IV 



V 



VI 



VII 



mo 



Dt6 OtOO 



iiP ko 6n666a6 it^hi 



^6hn6hni^^ 



ma 5a5^ 



d 



DiO 



iiiii tin 



Fig. 74. — Diagram to illustrate the inheritance of bleeding or 

 haemophilia. {After Bulloch and Fildes.) 



Mendel's laws. So consistent is this relation that, 

 as Ottenberg pointed out in 1921, the evidence 

 might be used in certain cases to determine the par- 

 entage of the child. The presence of two pairs of 

 factors will account for the results. Thus if one pair 

 of genes be represented by A and a and the other 

 pair by B and h, and if an individual with the ge- 



