1 62 LEO LOEB. 



terpretation of phenomena of inheritance. The concept of the 

 individuality differential is too new to have received much at- 

 tention from students of heredity. But von Dungern studied the 

 group agglutinins to which we have referred above and mentions 

 that they are inherited according to the rules of the inheritance 

 of simple Mendelian monohybrid factors. G. Schoene likewise 

 inquired how the characteristic of tolerance for skin grafts was 

 transmitted from parents to offspring and this author also came 

 to the conclusion that it was inherited according to the rules of 

 simple Mendelian heredity. Neither of these investigators, how- 

 ever, gives convincing data in this respect nor does Schoene refer 

 to the finer tissue reactions in his interpretations. Cur own ex- 

 periments lead us to a different conclusion. In the union of a 

 female, and male germcell of two individuals belonging to the 

 same species, two different individuality differentials are hybrid- 

 ized. How are the individuality differentials of the children? 

 Do they follow that of the father or that of the mother or do 

 the differentials of some children follow that of the father, while 

 those of others follow that of the mother? \Ye find that the 

 individuality differentials of the offspring are not identical at 

 least in the large majority of cases with the individuality differ- 

 ential of either of the parents, but that they have an intermediate 

 character; there exists, however, as we have shown, all transi- 

 tions between one and the other of the two individuality differ- 

 entials, if we compare the behavior of different children. We 

 have therefore a mode of intermediate or blending inheritance. 

 If we interpret this fact in Mendelian conceptions we must con- 

 clude that the individuality differential is represented by multiple 

 factors. 



INDIVIDUALITY AND SPECIES DIFFERENTIAL OF SUBSTANCES. 

 SPECIFICALLY ADAPTED SUBSTANCES. 



The cells and tissues of an organism contain, as we have seen, 

 the individuality and species differential ; they characterize each 

 individual and distinguish it from all other individuals. They 

 make a real indvidual out of a conglomeration of cells and tissues. 

 In order that these cells and tissues develop into an individual 



