114 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



the hosts. The outcome of these experiments also indicates that there was 

 a lack of a completely homozygous condition. 



In strain New Buffalo, only those grafts in which donors and hosts were 

 litter mates survived for greater lengths of time; lymphocytic infiltration 

 occurred in these transplants . 



In strain Old Buffalo the transplantations carried out were fewer in number 

 than in the other strains. As far as we can judge from these experiments, 

 the individuality differentials in this strain are farther removed from the 

 autogenous state than those in strains A, C3H, D, C57, and CBA. This con- 

 clusion would be in harmony with our findings in the related New Buffalo 

 strain, although in the latter the reactions against transplants from other 

 individuals, belonging to the same strain, was less severe than in the Old Buffalo 

 strain. 



On the whole our previous findings concerning differences or similarities 

 between the individuality differentials in the various inbred strains of mice 

 are therefore confirmed in these experiments. 



In general, we may conclude from all our experiments with closely inbred 

 strains of mice that, as with inbred rats and even with inbred guinea pigs, an 

 autogenous state of the individuality differentials has not yet been reached, 

 and that the degree to which this state has been approached differs in different 

 strains. However, it is probable that the differences in the severity of reactions 

 against transplants from other members of the same inbred strains are not 

 entirely due to the different degree to which the genetic constitutions have 

 become similar in the various individuals belonging to a strain ; it may be due 

 also to the differing intensity of the reactions of different hosts against a 

 similar degree of disharmony between the individuality differentials in a given 

 strain. Yet, after all, it is principally the differences in the genetic constitution 

 between the various members of a strain and therefore also the differences in 

 the individuality differentials of these animals, which determine the character 

 of the reactions against transplanted tissues and organs. All these experiments 

 add then new evidence for the conclusion that multiple factors determine the 

 nature of the individuality differentials and that the time of the appearance 

 of a reaction may be an indicator of the degree of disharmony between the 

 individuality differentials of different hosts and donors; if the disharmony is 

 relatively slight, the reaction may appear at a late date following transplantation. 



A complication may be caused by the fact that various organs and tissues 

 may differ very much in the intensity of the cellular reactions which they 

 induce in the host. We observed formerly that cartilage is relatively inert 

 and we attributed this characteristic to the relatively inactive metabolism in 

 this tissue. We have now found that also anterior hypophysis is a tissue that 

 remains relatively well preserved after transplantation and that calls forth 

 no lymphocytic reaction, or only a slight one. This organ is therefore not 

 well suited for the analysis of fine differences in the individuality differentials. 

 Furthermore, we see that different structures in the ovary induce the lympho- 

 cytic reaction to a very different degree; the yellow interstitial gland tissue 

 and also the corpus luteum tissue are quite active in this respect, while the 



