424 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



that the first homoiotransplant had elicited an increase in polymorphonuclear 

 leucocytes, a second homoiotransplantation of tumor was again followed by 

 a rise in the lymphocytes. 



Furthermore, a like sequence of events was noted when in a first homoio- 

 transplantation normal tissue was used and, sometime later, a piece of homoiog- 

 enous tumor. But if instead of homoiogenous tissue, heterogenous tissue was 

 transplanted and this was followed by a second transplant of homoiogenous 

 tumor, the reaction which followed the second transplantation was not modi- 

 fied by the first transplant. It is apparently only a first homoiotransplantation 

 which influences a second homoiotransplantation. The character of the or- 

 ganismal differentials of both the first and second grafts determines the mode 

 of reaction in the blood, but the tissue or organ differential, or the differences 

 between the differentials of normal and tumor tissue belonging to the same 

 species, is of no importance as far as this reaction is concerned. These very 

 interesting experiments of Blumenthal confirm, therefore, the conclusion that 

 in transplantation of both normal tissues and tumors the organismal differ- 

 entials are a very important factor in determining the kind of reaction of the 

 host against the graft, and the behavior of the lymphocytes and of the 

 polymorphonuclear leucocytes can be used as an indicator of the relationship 

 between hosts and transplants. It may then be concluded that as far as the 

 reactions in the cellular constituents of the blood are concerned, transplants of 

 various kinds of tumors, as well as autogenous tumors, behave like the corre- 

 sponding transplants of normal tissues, and that the reactions in both instances 

 depend on the relationship of the organismal, and in particular, of the indi- 

 viduality differentials of host and transplant, the differentials of the tumor 

 being essentially the same as those of normal tissues from which they are 

 derived. There is reason for connecting the increase in the number of polymor- 

 phonuclear leucocytes in the circulating blood which occurs during a later 

 period in the growth of transplanted as well as of spontaneous autogenous 

 tumors, with the same factors which were responsible for the anemic changes 

 which are noted in the bone marrow. 



In the case of normal tissues we have seen that differences in the constitu- 

 tion of the individuality differentials between host and transplant may cause 

 not only the invasion of the transplant by lymphocytes, but may also induce 

 a more active reaction of the connective tissue cells of the host against the 

 graft, and may tend to diminish the ingrowth of capillaries into the transplant. 

 The experiments of Burgess and Tyzzer indicate that also around a graft, 

 whose organismal differential differs markedly from that of the host, connec- 

 tive tissue growth may be quite active, and the resulting increase in the forma- 

 tion of fibrous tissue may still further contribute to the injury of the trans- 

 plant. But it is exactly the opposite condition, namely, a lack of ingrowth of 

 connective tissue, accompanied by a lack of ingrowth of blood vessels into 

 the graft, a lack of "stroma reaction" on the part of the host tissue, which, 

 according to Russell and Bashford, may result in the destruction of homoiog- 

 enous tumor transplants in immunized animals, and they believe the lack of 

 this reaction to be the mechanism through which the active immunity of the 



