TRANSPLANTATION AND INDIVIDUALITY. 155 



MULTIPLE AND SUCCESSIVE TRANSPLANTATIONS. 



We can demonstrate this fact also by multiple simultaneous 

 transplantations of the same kind of organ, for instance, the 

 thyroid from different individuals into the same host. The lobes 

 of thyroid taken from the same animal behave then in an approxi- 

 mately similar manner, while the lobes taken from different ani- 

 mals may behave very differently, each calling forth a lymphocytic 

 reaction in a quantitative way in accordance with the relationship 

 between host and donor. One piece can call forth a marked reac- 

 tion, while at the same time and in the same host another piece 

 proves rather indifferent. This indicates that the reaction is of 

 an entirely local character, called forth by the substances diffusing 

 from the transplanted cells into the neighboring tissue. It is not 

 primarily a general reaction of the character of an immune - 

 reaction, which would depend mainly on the presence of sub- 

 stances originating in response to the inoculation of the tissue and 

 carried through the circulation equally to all parts of the body. 

 The local character of the reaction we could prove still in another 

 way, namely by carrying out successive transplantations of the 

 same kind of organ into the same host. Under these conditions 

 the latent period of the lymphocytic and connective tissue reac- 

 tion was approximately the same after the first and second trans- 

 plantation. An immune substance which could have accelerated 

 the second reaction had, therefore, not been formed. In certain 

 cases, however, such an immune substance may actually develop 

 and hasten the appearance of a reaction around the transplant. 

 This takes place after inoculation with certain tumors. Thus it 

 comes about that the function of the lymphocytes has been misin- 

 terpreted in the case of tumor inoculations. It is believed that 

 they are solely concerned in the production of an immunity 

 against tumor growth. Our observations on the action of lymph- 

 ocytes in the case of transplantation of ordinary tissues, which 

 date back a considerable number of years, clearly prove that the 

 role of lymphocytes is a much more general one, namely, a direct 

 and local, quantitatively graded response to the homoio and syn- 

 genesiotoxins. The immunity reaction in certain cases of tumor 

 transplantation is merely a special case in a set of phenomena of 

 much wider biological significance. 



