56 



THE AM ERIC AX X AT U BALI ST 



[Vol. LIV 



Interchange of tissues between the children (brothers 

 and sisters) should give results identical with those of 

 autotransplantation, and transplantation of tissues from 

 one of the two parents to a child should in all children 

 give the same result, and the results should be those of 

 either auto- or homoiotransplantation. Or, it might be 

 possible that in the offspring a blending of the individu- 

 ality-differentials of both parents occurs. It might fur- 

 thermore be possible that in all children the same kind of 

 blending occurred or that all intermediate degrees of 

 blending of the differentials of father and mother be 



In using transplantation of tissue as a means of deter- 

 mining which of these possibilities is realized, we have to 

 take into account the difference in the situation of host 

 and graft. Under the usual conditions of transplanta- 

 tion the host is a self sufficient organism and is not in any 

 essential manner dependent for his nourishment upon 

 the graft. The graft on the contrary depends upon the 

 host for its nourishment. The relation between host and 

 graft is therefore not that of simple reciprocity. This 

 relation may be important in interpreting certain results 

 of transplantation as we shall see later. 



We have carried out two series of experiments in which 

 wo analyzed the mode of inheritance of the individuality- 

 differential, one in the rat 1 and a second one in the guinea 

 pig. 2 In the former we transplanted simultaneously 

 pieces from different organs into rats ; in the second we 

 used the thyroid gland for transplantation. We trans- 

 planted tissues from parents to children, from children 

 to mother and from brothers to brothers. Both series, 

 in the rat and guinea pig, gave the same result as far as 

 the main problem is concerned : the individuality-differ- 

 entials of the children are intermediate between those of 



2 Leo Loeb, Journ. Med. Research, 1918, XXXIX. 



