486 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



the greater the number of additional antigens which will be found in the 

 erythrocytes, the less will be the difference remaining between the totality of 

 these antigens in the erythrocytes and in the individuality differentials. 



Investigations as to the distribution of blood groups in different human 

 races we owe especially to Hirszfeld and his collaborators. In general, it may 

 be stated that the different primary blood groups are found in all races, but 

 the frequency with which the different groups occur differs in different popu- 

 lations and races. In general, in Western Europe A predominates ; the farther 

 we progress in the direction of India, the greater the frequency of B. In 

 certain more primitive races, such as the American Indian and the Eskimo, 

 O is the most common blood group ; but among the Black Feet Indians, Mat- 

 son and Schrader found a marked preponderance of Group A. As a rule, 

 among whites and negroes a certain agglutinogen may occur with varying 

 frequency. 



From these facts it may be concluded that the differences even between 

 supposedly pure races are essentially statistical as far as their blood-group 

 differentials are concerned. On the other hand, as stated above, different 

 species may possess the same kinds of blood groups. Conditions are different 

 in transplantation. Here a large number of very fine gradations in reactions 

 occurs in accordance with the relationship of donor and host. If we compare, 

 for instance, the results of transplantations of thyroid from rat to mouse, 

 or of the reciprocal transplantations, with those of syngenesio- and homoio- 

 transplantations in rats, we do not find in the former, in a single instance, the 

 excellent state of preservation of the thyroid transplant which may be ob- 

 served in a favorable syngenesiotransplantation from rat to rat ; we have here 

 to deal with absolute differences in the distribution of a large number of 

 factors, not merely with statistical differences in the distribution of a limited 

 number of factors as in the case of the four blood groups. In homoio- and 

 inter-racial transplantations we may find an overlapping of the results; but 

 the most favorable ones obtained in some syngenesiotransplantations are not 

 observed in inter-racial transplantations ; the differences in the results of dif- 

 ferent kinds of transplantation are therefore not merely of a statistical nature, 

 such as those obtained in comparing the blood groups in different populations. 



In order to analyze further the relations between blood-group differentials 

 and organismal differentials, we shall consider the occurrence of the former 

 in the cells and of agglutinins in the blood serum in different species of ani- 

 mals. However, some of the evidence concerning this subject is still contra- 

 dictory and the data on hand must, therefore, be used with caution. 



There can be no doubt that in certain anthropoid apes, as Landsteiner and 

 Miller have shown, there are group differentials which are identical with those 

 in man. Thus A and O corpuscles occur in chimpanzees, and A, B and AB 

 corpuscles in orang-utangs. In a Gibbon, A corpuscles were found. In the 

 blood serum of these species there are present agglutinins which react with 

 those differentials not present in their own erythrocytes. The agglutinogens 

 and agglutinins in these anthropoid apes behave exactly like the corresponding 



