178 IMMUNOLOGY 



above table after the groups of the parents and child are deter- 

 mined. It will also be noted that there are limitations to one's 

 ability to determine paternity by means of isoagglutination tests. 

 For a more comprehensive discussion of this subject the student 

 is referred to the studies of Ottenberg (1928), Snyder (1929), 

 Hooker and Boyd (1929), Wiener, Lederer and Polayes (1930), 

 and Wiener (1933). 



Bernstein's Triple Allelomorph Theory. — For all practical pur- 

 poses the assumption of Landsteiner that there are two agglu- 

 tinogens and two agglutinins for which reciprocal relationships 

 exist is quite satisfactory. However, the genetic formulas de- 

 veloped from such an assumption do not give data that explain 

 the racial distribution of blood groups; Bernstein (1925) de- 

 veloped an hjT)othesis which enables him to write formulas that 

 give data comparable to those observed. His theory is known 

 as the three factor or triple allelomorph hypothesis. In this he 

 assumes that the red cells of the group contain a recessive ag- 

 glutinogen designated by Snyder (1929) as and that there exists 

 a corresponding agglutinin o. He furthermore assumes that the 

 agglutinogen is present in some bloods of group A and also 

 of group B but never in group AB, He postulates that all three 

 agglutinins are present in all sera, but that there exists a recipro- 

 cal binding between an agglutinin and its corresponding ag- 

 glutinogen that prevents autoagglutination. Thus he assumes 

 the existence of six genetic types. Snyder* has illustrated these 

 assumptions in the following diagram. 



Group O A B AB 



Agglutinogen 66 Ao AA Bo BB AB 



Agglutinins ab(6) (a)b(6) (a)b6 a(b)(o) a(b)o (a)(b)6 



In this diagram it will be observed that the agglutinins in- 

 volved in a reciprocal binding with the corresponding agglutino- 

 gens in the red cells are enclosed in parentheses. The reciprocal 

 binding prevents autoagglutination. Conclusions concerning non- 

 paternity are not in confiiet in the two theories except where AB 

 parents are involved. Reference to Table V shows that accord- 



*Snyder: Blood Grouping- in Relation to Clinical and Legal Medicine, Wil- 

 liams and Wilkins Co. Published by permission of Snyder and Williams and 

 Wilkins Co, 



