DIFFERENTIALS OF CLOSELY INBRED ANIMALS 87 



ent litters as well as those between brothers and sisters elicit a much less an- 

 tagonistic reaction in series III than in series I. As compared with series II, 

 the grades are higher in series III in transplantations between different litters. 



In transplantations between brothers and sisters the results are better in young 

 rats of group (1) in series III than in series II, but about the same in the 

 older rats of group (2). We may then conclude that considerable progress has 

 been made in the direction towards a homozygous condition from series I to 

 series III, and that progress has also been made from series II to series III, 

 although even in series II the reactions between brothers and sisters were 

 much less antagonistic than in series I. 



In all three series the reactions against transplants between different families 

 (A and B) were about alike and corresponded to homoiogenous relations of 

 the individuality differentials. The grades, both in the transplants between 

 different litters as well as between brothers and sisters of the hybrids (AXB), 

 corresponded to autogenous relations of the individuality differentials in group 

 1. In group 2, the grades of transplants between different litters of hybrids 

 were those of an average syngenesio-reaction ; they were much less favorable in 

 group 2 than in group 1. But the reactions in groups 1 and 2 of series III were 

 much better than the corresponding reactions in series II. Also, the reactions 

 in transplantations from Family A to the hybrid or from the hybrid to Family 

 A were much milder in series III than in series II. In series III these reactions 

 in young rats of group 1 corresponded to good syngenesiotransplantations, 

 while in the somewhat older rats of group 2 they corresponded to syngenesio- 

 reactions of medium intensity. The average was slightly, but not markedly, 

 higher in transplants from family A to the hybrid than in the reciprocal trans- 

 plantations. Similar results in this regard were obtained in series II, and this 

 might be expected if a completely autogenous condition of the individuality 

 differentials had not yet been attained in the families A and B. 



Of interest in the third series is also the difference in the grades in the 



