DIFFERENTIALS IN CLOSELY INBRED GUINEA PIGS 93 



13 as a host and to an increased injuriousness of its individuality differentials. 

 In family 32, the opposite conditions obtain. 



F. Transplantations from a parent family to a hybrid. Also in this group 

 of experiments the actual parents of the hybrids were not used in these trans- 

 plantations, but other members of the corresponding families. 16 experiments 

 were carried out. Examination took place between 25 and 35 days. The reac- 

 tions were much milder in this series than in the reciprocal series E, except in 

 one case, in which 2N-52 was transplanted to a hybrid between families 2 and 



(2-22 

 13y (CY-0 j . " _-. Here, the grade was 1. Whether in this instance the donor 



2N happened to carry some genes strange to the family 2 component of the 

 host, or whether some error entered into this transplantation, is uncertain. The 

 fact may be recalled in this connection that the line 2N had not been propa- 

 gated by strict brother-sister matings. Omitting this last transplantation, the 

 average grade in the remaining 15 transplantations was 3.05, a grade similar 

 to those obtained in transplantations between brother hybrids in inbred fami- 

 lies, which were 2.94 and 3.12. If we include the transplantation with grade 1, 

 the average grade was 2.92. If we omit again this one transplantation, there 

 were six of 15 experiments in which the grades were below 3, namely, 2.87 

 and 2.75 ; these grades were characteristic of a favorable syngenesio-reaction, 

 while in the other cases the reaction approached closely the autogenous state. 

 Taken as a whole, the grades were very good in this series and they came near 

 to those characteristic of autogenous reactions, but a fully homozygous con- 

 dition had not yet been reached. 



From these data, it may be concluded that transplantations from hybrids to 

 one of the parent families did not elicit homoiogenous reactions, but, instead, 

 severe syngenesio-reactions. It seems possible that in this case the presence of 

 gene sets common to donor and host mitigated the intensity of the reaction of 

 the parent- family serving as host against the strange component of the hybrid- 

 transplant. On the other hand, transplantation from a parent-family to the 

 hybrid-host did not give a perfect autogenous reaction, since some of the genes 

 of the parent may be strange to the corresponding constituent of the hybrid; 

 therefore, in a number of cases, syngenesio-reactions were obtained. Another 

 possible factor affecting the result in these experiments was the apparent 

 tendency of certain families to elicit a more severe reaction, or to respond 

 more aggressively themselves than others; thus the involvement of families 

 13 and 35 in the transplantation seemed to cause a relatively severe, and that 

 of family 32 a more mitigated reaction. As stated previously, there is some 

 indication that the reaction may be stronger in the presence of family 13, be- 

 cause in this family the various members may have a smaller number of 

 common brother-sister matings than in some other families; but such a con- 

 dition should not affect the severity of the reaction of a family other than 13 

 serving as host against a hybrid containing the gene set of family 13; in this 

 case, other conditions must be responsible for the severe effect. 



G. Transplantations between hybrids, in which donor and host were com- 

 posed of the same two inbred families but were not brothers or sisters. 14 



