Chapter J 



The Relation Between Growth Energy, Adaptive 



Processes and Organismal Differentials in 



the Transplantation of Tumors 



In order to evaluate the role which organismal differentials play in the 

 growth and transplantability of tumors, it will be necessary to consider 

 separately certain variable factors which, in their interaction with 

 organismal differentials, may influence the results of transplantation. Among 

 these the most important ones are changes in growth energy and adaptive 

 processes which may take place in the tumor in the course of serial trans- 

 plantation in response to conditions present in the host; processes of im- 

 munity may also be considered as adaptive changes, but they occur in the 

 host as a reaction to the growth of the tumor. Adaptive processes in the 

 tumor may consist in changes in the readiness with which organismal (indi- 

 viduality) differential substances are produced and given off into the circu- 

 lation of the host; likewise, the sensitiveness of the tumor and its power of 

 resistance to injurious substances of the host may be modified; this would be 

 added to primary differences in the sensitiveness which distinguish different 

 types of tumors. 



However, the degree of adaptability of a tumor to a new environment 

 may be determined, in addition, by variations in growth energy which may 

 take place in the course of serial transplantation. The growth energy of 

 tumors was considered by us (1905) as one of the factors on which depends 

 their transplantability, a low degree of growth energy rendering transplanta- 

 tion more difficult. In addition, we recognized in the host, as significant for 

 the fate of the graft, a factor corresponding to what we later defined as 

 individuality and species differentials. Among the growth factors we dif- 

 ferentiated those inherent in the tumor cells (Gi) from others circulating 

 in the bodyfluids of the host (Ge), and furthermore, we differentiated factors 

 which permit a tumor to live, without necessarily enabling it to grow, from 

 other conditions which enable it to grow. The growth energy was measured 

 by the duration of the period of latency as well as by the rapidity of growth 

 of the visible tumor. Different tumors were seen to differ very much in their 

 growth energy and in their ability to withstand the injurious conditions 

 associated with the process of transplantation, and among the latter there 

 were some tumors which did not grow even after autotransplantation. We 

 distinguished, therefore, between weakly and rapidly growing tumors, be- 

 tween temporarily and permanently growing tumors, and between transplant- 

 able and non-transplantable tumors; also between stable and labile tumors, 

 the former retaining their growth energy unaltered, the latter, as a result of 



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