SYNGENESIOTRANSPLANTATION 81 



number of transplantations was made in the third series. The time of ex- 

 amination varied between 7 and 40 days in the different experiments ; only 

 those transplants examined not earlier than 17 days after transplantation were 

 included in series III, while in series II some experiments are included in 

 which the examination took place at an earlier time. 



TABLE II 



The average results obtained are shown in the accompanying table II. There 

 is only one average figure for homoiotransplantation given ; it was obtained in 

 series I and it is probably too high ; this is due very likely to the fact that only 

 a rather small number of transplantations was made, and that among these 

 there were two grades which exceeded the usual range in homoiotransplanta- 

 tion, one of them closely approximating the results obtained in autogenous 

 transplantations. It is possible that in this instance we had to deal with related 

 guinea pigs. If we make allowance for this discrepancy, the table shows that 

 the grades in syngenesiotransplantations are higher than in homoiotransplan- 

 tations, but that they are nearer those characteristic of homoiogenous than of 

 autogenous transplantations. This was true also in the experiments with rats, 

 which we have already discussed. 



Taking these grades as a whole, the results of the syngenesiotransplanta- 

 tions are intermediate between those obtained in autogenous and homoiogenous 

 transplants in either of two ways : (1) In a number of experiments the grades 

 in the individual experiments vary, approaching either the results in autoge- 

 nous or in homoiogenous transplantations. In these cases it is merely the aver- 

 ages which are intermediate. (2) In other transplantations the grades of the 

 individual experiments are intermediate. In order to understand the manner 

 in which such an intermediate condition may come about, we may distinguish 

 in the reaction against the transplants on the part of the host cells, two periods, 

 the first one tending from 6 to 12 days following transplantation, the second 

 one covering the time from the 12th day to the time of examination. The re- 

 actions in the thyroid gland may be cited as an example of varying results in 

 these two periods. During period I, the connective tissue reaction takes place. 

 If during this time the production and accumulation of injurious individuality 

 differential substances around and in the transplant has been strong, there 

 is an active ingrowth of connective tissue cells towards the center of the graft 

 and this tissue soon becomes transformed into hyaline substance; the ingrowth 



