No. G30] THE 1X1)1 VI DUALITY Dl 11EBENTIAL 



57 



are found varying between those approaching identity of 

 individuality-differentials on the one extreme and 

 homoio-differentials on the other. 



In the guinea pig we analyzed further the difference in 

 the results after transplantation of tissues from brother 

 to brother, from mother to child and from child to mother. 

 "We found transplantation from brother to brother to 

 give the best results, but even here the mixing of the indi- 

 viduality-differentials called forth the development of 

 toxins, syngvnesiotoxins, which usually were relatively 

 mild, but in certain cases would be more severe. Trans- 

 plantation from child to mother led to the production of 

 toxic effects which were almost as marked as those pro- 

 duced by the homoio-toxins. Transplantation of tissues 

 from mother to child on the whole resembled that of 

 transplantation from brother to brother, but seemed to 

 be somewhat less favorable. In the rat there were like- 

 wise indications that the transplantation from child to 

 mother was more unfavorable than the others, but a de- 

 cided difference between transplantations from mother 

 to children and from brother to brother could so far not 

 be established. However, the indicator of effects which 

 we used in our guinea pig series was liner than that in 

 our rat series. 



We have begun experiments to determine the behavior 

 of individuality-differentials in the second generation. 

 It seems that here too the results are intermediate, but 

 further experiments need to be carried out, before a defi- 

 nite statement can be made. 



In a provisional way we may attempt to explain these 

 results as follows. In most cases each individual has at 

 least two sets of individuality-differentials, one inherited 

 from the father, the other from the mother. Each set 

 again consists of two kinds of differentials. There may 

 be added individuality-differentials from some further 

 distant ancestors, but this complication may be ignored 

 at present; in certain individuals the differentials of 

 either father or mother are lacking. We may assume 



