Chapter J 



The Mechanism of the Reactions Against 



Homoiogenous Individuality Differentials; 



Autogenous Tissue Regulators 



1. Various phases which follow auto and hotnoio transplantation. It fol- 

 lows from the observations discussed in the preceding chapters, that after 

 transplantation there is a first phase in which there is no noticeable difference 

 between the conditions of autogenous and homoiogenous transplants. This 

 phase is dominated by the injury due to the process of transplantation and 

 by injurious conditions existing in the new location of the tissue. The damage 

 to the tissues is followed by regenerative reactions ; the homoiogenous tissues 

 are subjected subsequently, during the second phase, to further specific 

 injuries by the host and these may also call forth regenerative processes as 

 long as the injury has not progressed too far. These injuries, furthermore, 

 initiate the activity of the host connective tissue, which moves towards the 

 transplants. There originate, thus, general, partly non-specific changes, which 

 are based on attributes of the grafted tissues and of the host tissues. 



This first phase is followed by a second one, in which differences develop 

 between the autogenous and the homoiogenous transplanted tissues. There is 

 a preponderance of regenerative growth processes and regulative processss 

 in the autogenous transplants, and there are injurious effects which the host 

 exerts on the graft under the influence of homoiogenous individuality differ- 

 entials. The latter tend to prevent a satisfactory recovery of the transplanted 

 homoiogenous tissue from the injuries received during the first phase, and 

 they cause additional damage to the homoiogenous transplant, which thus, in 

 many cases, cannot maintain itself and during the third phase is gradually 

 destroyed. These are the characteristic features of the second and third phases 

 following transplantation, in which differences between the conditions of the 

 autogenous and homoiogenous tissues become more and more marked. How- 

 ever, there occur, also, changes opposed to this outcome, namely, conditions 

 of adaptation between transplant and host, which in certain instances may 

 slowly lead to an improvement in the state of the homoiogenous transplant and 

 may make possible its survival in the strange host. 



As to the mechanisms leading to the secondary injury of the homoiogenous 

 tissue, they consist, in the first place, in the action of the homoiotoxins of the 

 host, and secondly, in the activities of the host cells ; the most specific among 

 the latter are the reactions of the lymphocytes ; but also the behavior of the 

 connective tissue and blood vessels is influenced by the homoiogenous charac- 

 ter of the individuality differentials. Furthermore, the age of the host in- 

 fluences the action of the connective tissue ; the latter is diminished if the host 

 is very young. It seems that in every instance the homoiotoxins act on tissues 



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