BLOOD GROUPS, HETEROGENETIC ANTIGENS 481 



group differentials in various species, or when we analyze the relationship 

 between Forssman and blood-group differentials, and these results are inter- 

 preted as indicating that the various differentials have certain sidechains in 

 common, while they differ in respect to others ; or it is assumed that antigens 

 with a blood-group, Forssman, species or organ differential, which are unlike 

 in different individuals, are associated with other differentials (antigens) 

 which are the same in two individuals and which explain the partial con- 

 cordance in the results obtained in the testing of the antigens. 



It is a very characteristic feature of the individuality differentials, and of 

 the organismal differentials in general, that they occur in all or almost all of 

 the various tissues and organs of a certain individual or species and are not 

 restricted to one particular type of cell or tissue. At first it appeared as if the 

 blood-group differentials were limited to the erythrocytes, but subsequently 

 they have been found also in other cells, and according to Kritschewsky and 

 Schwarzmann, they occur in all the organs of an individual, except the lens 

 of the eye. The blood serum also seems to contain blood-group differentials, 

 but here they are present in only a small quantity and are apparently covered 

 up by other substances. They gained access to the body-fluid, presumably 

 secondarily, perhaps as the result of the destruction of certain cells. As we 

 have seen, also individuality-specific substances are present in the blood 

 serum. In addition to the blood serum, various secretions, such as saliva and 

 urine, may contain blood-group differentials. Landsteiner and Levine demon- 

 strated "blood-group specific substances" in human spermatozoa, which had 

 been freed from the sperm fluid through centrifugation and subsequent wash- 

 ing with salt solution. This observation suggests that germ cells contain pre- 

 formed blood-group differentials ; otherwise we should have to assume that 

 some of the constituents of the sperm fluid may have adhered to the sperma- 

 tozoa, or that a precursor substance of the fully developed differentials, rather 

 than the latter themselves, was responsible for the group antigen reaction. 



In regard to their general distribution among various tissues, blood-group 

 antigens and organismal differentials behave, then, in a similar manner. As to 

 the Forssman differentials, in one species they may occur only in the erythro- 

 cytes, in another species in the kidney, and perhaps also in the liver ; in still 

 others they may be found in the erythrocytes as well as in the kidney, and 

 in the guinea pig they are present in the kidney, but only in the erythrocytes 

 of certain individuals. In man, according to Schiff and Adelsberger, the 

 Forssman differential is present in those corpuscles which possess the blood- 

 group differential A ; according to Kritschewsky, it is present also in various 

 organs, but not in the brain. However, it is possible that blood-group A and 

 the Forssman antigen have certain chemical characteristics in common, while 

 they differ in respect to others ; or there may be perhaps not even an identity 

 of certain chemical groups, but merely a chemical similarity in these two 

 antigens. This similarity in chemical structure may lead to an overlapping 

 in the action of the resulting antibodies. In their wide distribution in human 

 tissues the blood-group differentials would then differ from the typical organ 

 differentials which, on the whole, are limited to one organ, although different 



