484 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



a single dominant gene. Thus seventy-two classes of individuals can now 

 be distinguished if one considers all these factors, and there is little doubt that 

 the number of such differentials could be increased still further. Still more 

 recently, the agglutinogen Rh, which is common to man and the Rhesus mon- 

 key, has been added to the list of blood-group antigens. 



Notwithstanding the possibility of finer differentiations of individuals by 

 such means, these blood-group differentials are not identical with the in- 

 dividuality differentials, according to the evidence which is available at the 

 present time. The fact that two individuals belong to the same primary blood 

 group does not seem to have any relation to the reaction which takes place if a 

 piece of skin is transplanted from the one to the other. Furthermore, inasmuch 

 as Aj and A 2 represent subgroups of A, the same objection applies to the 

 identification of these subgroups with the individuality differentials as to the 

 primary group A. In regard to the M, N and P differentials, they are appar- 

 ently inherited in a similar manner to the four primary blood groups ; neither 

 they nor H, as such, would make possible a differentiation between different 

 individuals. But even if it should be possible to distinguish individuals by 

 means of these additional blood groups, it has not been shown that the mode 

 of distribution of blood-group differentials among the different individuals 

 corresponds to their degree of relationship, and even if contrary to expectation 

 there should be found such a parallelism, it would still remain improbable 

 that these differentials are identical with the individuality differentials so 

 generally found among all kinds of species and animals, including those in 

 which these particular blood-group differentials are lacking. 



In addition to the secondary blood group or subgroup differentials, there 

 occur other unusual agglutinogens and agglutinins in the blood of various 

 individuals, or in certain classes of individuals. Several authors — Guthrie 

 and Huck, Ottenberg and Johnson, and others — have already drawn attention 

 to such occurrences. Thus it seems that especially in cases of insanity abnormal 

 agglutination reactions have been observed. Furthermore, if the union between 

 agglutinogen and agglutinin takes place at a low temperature, abnormal ag- 

 glutinations may result, which are not found at ordinary temperature. Other 

 complications are due to an apparent linkage which has been noted between 

 certain types of agglutinogens or agglutinins. Thus an agglutinin for A 2 

 usually causes an agglutination also of blood corpuscles which belong to 

 the primary blood group I, possessing neither A nor B. Agglutinin alpha x of 

 human sera from groups I and III can be removed by blood cells of Group A, 

 which lack the A x receptor. It is possible that with the agglutinogens N and 

 P, there may be associated other agglutinogens which increase the agglutina- 

 tion effect normally produced by the union of N and P and their respective 

 agglutinins ; perhaps anti-human species agglutinins may be active in anti-N 

 or anti-P rabbit immune sera and cause agglutination in addition to the 

 specific agglutination of the N and P corpuscles. Agglutinins for human P 

 agglutinogen have been observed also in sera of horses, hogs and rabbits. An- 

 other indication of the complexity of this mosaic of antigens is the existence 



