DIFFERENTIALS IN CLOSELY INBRED GUINEA PIGS 97 



in the intensity of reactions of hosts against transplants. Although, as stated, 

 it is much easier to bring about a great similarity in the constitution of the 

 individuality differentials through continued close inbreeding of certain 

 families in guinea pigs than in rats, we have seen that even in guinea pigs, 

 after a considerable number of generations of brother-sister matings, a com- 

 plete identity of the individuality differentials has not yet been reached. In 

 accordance with this fact is the observation that, a small number of genera- 

 tions of brother-sister matings does not seem to cause a marked increase 

 in the similarity of the individuality differentials in guinea pigs, as shown 

 in series III of these experiments. 



