142 Inheritance of Specific Iso-agglutinins in Human Blood 



Theoretical Considerations, 



The division of human sera into four groups, in the manner suggested 

 by Moss, has tended to some degree to obscure the problems connected 

 with the inheritance of those qualities upon which the classification is 

 based. Taking as the precise quality the agglutinophilic reactions of the 

 red cells of the blood, inspection of the table above reveals the fact that 

 there are but two such characteristics fundamentally present in human 

 blood — namely those possessed by individuals of Groups II and III. 

 Group I consists of individuals in whose red cells both these characteristics 

 are found ; while in the red cells of individuals belonging to Group IV 

 neither characteristic is present. Similarly, the iso-agglutinating power 

 of a Group IV serum is built up from the presence, and that of a Group I 

 serum from the absence, of both the iso-agglutinating capacities which 

 separately characterise the sera of Groups II and III. That the individual 

 agglutinophilic capacities of Group II cells and Group III cells are 

 mutually exclusive, i.e. that one such characteristic cannot be present at 

 the same time as the other, is precluded by the existence in Group I of 

 cells which display both capacities towards appropriate agglutinating 

 sera. Similarly, the agglutinating capacity of Group IV serum affords 

 proof of a similar condition of affairs with regard to the iso-agglutinins 

 found in Groups II and III respectively. The work of Landsteiner 

 makes it abundantly clear that the agglutinating power of the serum of 

 a blood, and the agglutinophilic capacity of its red cells, are reciprocal 

 in terms of the aforesaid characteristics. That is, a Group II blood, in 

 which the red cells are agglutinable by a Group III serum, has in its 

 own serum an agglutinin for the cells of a Group III blood ; and vice 

 versa. So also Group I blood contains no iso-agglutinin in its serum ; 

 and a Group IV blood contains iso-agglutinins for the red cells of 

 Groups I, II. III. 



Von Dungem and Hirschfeld (1911) give the symbol a to the iso- 

 agglutinophilic capacity displayed by Group II red cells, and /S to that 

 displayed by Group III red cells. These symbols define the specificity both 

 of the agglutinophilic capacity of the red cells, and of the iso-agglutinin 

 in the serum, if cognisance be taken of the work of Landsteiner referred 

 to above. The cells of Group IV, which show no iso-agglutinophilic 

 capacity, they consider to carry properties which they name non-a and 

 non-/3. To bring this terminology into line with that generally adopted 

 in genetics we may regard the agglutinophilic capacity as due to definite 



