Chapter 6 



Regeneration, Transplantation, and the 

 Autogenous Tissue Equilibrium 



IN earlier periods of the experimental study of transplantation a dis- 

 cussion arose between two French biologists, Yves Delage and Giard, 

 as to the relation which exists between transplantation and regeneration. 

 Yves Delage maintained that there is an antagonism between these two proc- 

 esses. He based this conclusion on the very great regenerative potency in 

 lower organisms, such as planarians and lumbricidae, which renders trans- 

 plantation difficult, because the new tissue developing in or near the surface, 

 which separates host and transplant, tends to push off the transplant. Plants, 

 on the other hand, in which the tendency to regeneration is very slight, are 

 very suitable for grafting. However, according to Giard, such an antagonism 

 does not exist. He cited the fact that in tunicates, sponges and corals, where 

 the regenerative power is great, transplantation can readily be accomplished. 

 In previous chapters we have mentioned the importance of regenerative 

 processes in the fate of transplants; we shall now consider these facts in a 

 connected way, because they have an important bearing on the establishment 

 of the autogenous equilibrium in higher organisms, which holds together the 

 various organs and tissues, as well as different parts, in the same organ or 

 tissue, and unites them into one individual. This equilibrium is autogenous in 

 higher organisms, because adjoining tissues need to possess the same individu- 

 ality differential. The proof of the existence of such an equilibrium is based 

 largely on the absence of regenerative growth phenomena whenever adjoining 

 autogenous tissues or constituents of the same tissue balance one another in 

 such a way that there is a relative state of rest and a lack of interference with 

 the neighboring tissues. To such a state of formative equilibrium there must 

 correspond a similar equilibrized state of metabolic and functional interactions 

 of tissues; whenever a replacement of the autogenous tissue constituents by 

 homoiogenous constituents alters this equilibrium, regenerative movements 

 and growth tend to take place, and thus antagonisms between adjoining tissues 

 may become manifest ; these changes may be taken as an indication that an 

 autogenous equilibrium has existed before the disturbances became manifest. 

 As the following discussion will show, in certain respects there does exist an 

 antagonism between the regenerative activity of the host and the successful 

 outcome of transplantation. There are conditions in which the tendency of 

 the host to regenerate may be responsible for the casting off or the resorption 

 of the transplant; but, on the other hand, there are also conditions in which 

 the transplant may prevent regenerative processes in the host ; this it may do 

 if, owing to the nature of the organismal and organ differentials of host and 

 transplant, the contact mechanisms at the point of junction between the 



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