DIFFERENTIALS IN CLOSELY INBRED GUINEA PIGS 91 



row, spleen, ovary, liver, adrenal gland, testicle and pancreas were trans- 

 planted, the grades were as follows : In two transplantations in family 32, and 

 in one case in family 13, the grades were 3 + , corresponding to autogenous 

 transplantations. In three cases in family 13 and family 32, the grades were 

 3— and 3— /2+, corresponding to favorable syngenesiotransplantations, and 

 in three experiments in family 2, the grades varied between 2+ and 2, cor- 

 responding to moderate or severe syngenesio-reactions. Liver and adrenal 

 gland were not preserved at this late period, while they were well preserved 

 after from 27 to 37 days ; likewise, spleen was not well preserved. Pancreas 

 was never recovered. Testicle tubules lined with Sertoli cells were seen. Again 

 it was observed that the lymphocytic infiltration can occur at a late period, and 

 that a fully homozygous condition has not yet been attained in the various 

 families. In two additional experiments in family 2, the donors were the off- 

 spring of parents which represented hybrids between two different individuals 

 belonging to family 2. For two generations this hybridization had taken the 

 place of the usual brother and sister matings. The hosts were the offspring of 

 continued brother-sister matings in family 2. The grades were 2 and 2.50, 

 which correspond to average grades in syngenesiotransplantations. 



The average grades in the various subdivisions of group A were as follows : 

 2.91; 2.87; 2.56; 2.99; 2.66. The total average grade was 2.72, which cor- 

 responds to a favorable syngenesio-reactio'n. This confirms the conclusion that 

 a complete identity of the individuality differentials within the various closely 

 inbred families of these guinea pigs has not yet been reached. 



B. Control experiments in which tissues were transplanted to non-related 

 guinea pigs. Examination took place 20 to 40 days later. (1) Transplanta- 

 tions from one inbred family to another inbred family : The grades varied be- 

 tween 2-/2 and 1. The average grade was 1.27, which corresponds to a severe 

 homoiogenous reaction. The most severe reactions were obtained in trans- 

 plantations in which family 13 was the host or was one of the constituents of 

 a hybrid. (2) Transplantations from non-inbred B to B stock, or from hybrids 

 between inbred families to B stock hosts: The average grade was 1.11. 

 (3) Similar results, with an average grade of 1.11, were obtained in trans- 

 plantations from B stock to St. Louis stock. In all these experiments the grades 

 were characteristic of homoiogenous transplantations. 



C. Transplantations between brothers or sisters in inbred families. Families 

 35, 32, 2 (2N) and 13 were used in these experiments, in which examination 

 took place from 30 days to 5% months after transplantation. In the trans- 

 plantations in these various families, including family 13, the grade was 3 + , 

 except in one case, in 13-9, where it was 3 — , corresponding to a favorable 

 syngenesio-reaction. The somewhat lower grade in this instance was presum- 

 ably due to the fact that here close inbreeding had not yet continued long 

 enough. In two cases, transplantations between brothers which were hybrids 

 of different generations within the same family were carried out, namely, in 

 family 13 and in family 32; in both, the grade was 3 + . As was to be ex- 

 pected, in the brother-to-brother transplantations autogenous reactions were 

 approached to a still higher degree than in the transplantations between differ- 



