BLOOD GROUPS, HETEROGENETIC ANTIGENS 487 



human group differentials and agglutinins. This relationship of the group 

 differentials corresponds to the close relationship existing between the or- 

 ganismal differentials of man and these apes. However, notwithstanding the 

 identity of group differentials in these organisms, a very marked difference 

 exists as far as the organismal differentials in man and anthropoid apes are 

 concerned. Injection of human red corpuscles into chimpanzees leads to the 

 production of species-specific antibodies, which allow the differentiation be- 

 tween human and chimpanzee blood (Landsteiner and Levine), although 

 both of these may possess the same blood-group differentials. This fact again 

 demonstrates the distinction between organismal and the original blood-group 

 differentials. The combination of blood-group antigens M and N has been de- 

 tected so far only in the blood of primates, but the M differential seems to 

 occur also in the Macacus Rhesus erythrocytes. 



If we turn to the lower monkeys, Landsteiner and Miller found among 

 Old World monkeys no blood-group differentials which correspond to human 

 isoagglutinogens, while New World monkeys, which are less nearly related to 

 anthropoids than Old World monkeys, have a differential analogous to human 

 differential B, although B of man and monkey are not identical in this instance. 

 Among the Old World monkeys it is especially Macacus Rhesus that has been 

 studied very extensively. According to Buchbinder, the erythrocytes of 

 Macacus do not possess a differential corresponding to the human blood-group 

 differentials, but in the blood serum of this species there is found the iso- 

 agglutinin alpha, which agglutinates human corpuscles A. However, more 

 recently it has been observed that antigen Rh is common to human and 

 Macacus Rhesus erythrocytes. No Forssman differential exists in Macacus 

 erythrocytes or kidney, but there is a hemolysin for sheep corpuscles in 

 Macacus serum ; however, this hemolysin seems not to behave in the ex- 

 pected way towards the corpuscles of other species which contain Forssman 

 differentials. Macacus erythrocytes do not contain blood-group differentials 

 A and B, and no classification of Macacus blood into groups is possible. As 

 Eisler has found, human corpuscles have also a differential distinct from the 

 Forssman differential, in common with Shiga bacilli. 



We see, then, that to a certain extent the blood-group distribution is con- 

 nected with the phylogenetic relationship of animals ; the anthropoid apes have 

 blood groups more similar to those of man than the lower monkeys and other 

 animals. However, this is a condition which is not restricted to blood groups, 

 but which is observed likewise in other organ characteristics ; thus the shape 

 of the skull and brain, and many other features, are in apes, more similar to 

 those of man than are those of other animals. On the other hand, this paral- 

 lelism between relationship and blood-group distribution is not general and, 

 moreover, we find quite similar characters shown equally by very diverse 

 organisms, without respect to their relationship. 



The investigations in apes and monkeys were preceded by those concerning 

 the blood groups in other mammals. At first the same methods which had led 

 to their establishment in man were used also in the case of various animal 



