DEMONSTRATION OF INDIVIDUALITY DIFFERENTIALS 515 



on the other hand, the character of various tissues and organs of one in- 

 dividual is contrasted with that in another individual ; this is possible because 

 the individuality differential is not merely an attribute of one particular kind 

 of cells, such as the erythrocytes, but is present in the various tissues and 

 organs of an individual. 



We find, in general, in the serological tests a lack of those fine gradations 

 between intensities of reaction, which correspond to the degrees of relation- 

 ship of the partners, observed in cases of transplantation. In transplantation 

 experiments the cells and tissues transferred to a strange environment set in 

 motion finely graded cellular mechanisms of attack in the host and the trans- 

 plants are also acted upon by the graded injurious actions of the host body- 

 fluids. In the experiments of Ehrlich and Morgenroth, as well as in those 

 of Todd, the antigens of the red corpuscles initiated the production of im- 

 mune hemolysins or immune agglutinins. On the whole, these latter reactions 

 resembled either autogenous or fully developed homoiogenous reactions, al- 

 though in the hemolysis tests certain gradations in the intensity of hemolysis 

 were found in different combinations of corpuscles and immune sera in some 

 instances, and such gradations were apparently in accordance with the rela- 

 tionship between the animal whose blood corpuscles were tested and the 

 animal serving as the immune-body producer. Is this difference between the 

 reactions following transplantation and the effects of immune sera due to a 

 difference in the differentials or antigens which participate in these two tests? 

 Presumably it depends largely on the more finely graded reactions exhibited 

 by living tissues, as compared with the in vitro reactions between antigen 

 and antibody. 



The antigens present in the erythrocytes are substances which can be 

 partly or wholly neutralized or removed through absorption with the corre- 

 sponding antisera. When a certain degree of relationship exists between the 

 donors of the erythrocytes and the various animals to be injected with these 

 cells, the correspondence between the immune bodies and the antigens may be 

 sufficiently great to make possible the complete removal of these immune sub- 

 stances by the erythrocytes of the donor. These differences between antigens 

 may conceivably depend upon chemical groups forming part of one complex 

 substance, or perhaps we may have to deal with distinct substances. These 

 antigens, which ultimately are derived from genes situated in the nucleus, are 

 themselves situated outside the nucleus; at least this is the case in the non- 

 nucleated erythrocytes. 



We have seen that the individuality differentials are preformed and there is 

 reason for assuming that they elicit homoioreactions in transplantation di- 

 rectly, at least to a large extent, and that these reactions do not primarily 

 depend upon the formation of immune bodies, although secondarily, immune 

 reactions may occur. Similarly, the solution of the foreign blood corpuscles, 

 after intravenous injection into homoiogenous hosts, depends primarily upon 

 the incompatibility between the strange individuality differentials of the 

 erythrocytes and the bodyfluids of the host, and the formation of immune 

 substances is a process caused by this primary incompatibility. While it has 



