110 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



which the individuality differentials have become more similar although not 

 yet completely identical, accumulations of lymphocytes may still allow a grad- 

 ing of the different degrees of homozygosity which have been attained. The 

 lymphocytes invade first the tissues adjoining the ovaries, and only later the 

 ovary proper. Within the ovary the lymphocytes invade the granulosa of 

 preserved follicles last; they seem to be especially attracted by the yellow 

 vacuolated interstitial gland tissue, which corresponds closely, in some re- 

 spects, to certain cell complexes found in the cortex of the adrenal gland in 

 mice. In both of these organs vacuolated cells may act as phagocytes, neigh- 

 boring cells may coalesce, or the nuclei may form central rosettes. By the 

 combined use of the lymphocytic reaction and of the survival of the various 

 types of follicles as tests for the individuality differentials, the strains can be 

 arranged in the following order of decreasing homozygosity: (1) strain A; 

 (2) strains C3H and CBA; (3) strains C57 and D; (4) strain New Buffalo; 

 (5) strain Old Buffalo, and (6) strain AKA. In strain Old Buffalo, the best 

 results were obtained if the ovaries were transplanted into ovariectomized sis- 

 ters, but neither ovariectomy nor the close relationship between donor and host 

 alone was sufficient to insure a good preservation of the follicles. However, in 

 general there are conditions in which, with the aid of a hormone constellation 

 that is very favorable for the survival or growth of the transplanted ovaries, 

 the latter may be preserved and the follicles may grow even in transplants 

 from different litters. This was the case after transplantations, for long 

 periods of time, into castrated males ; such mice offer, perhaps, the most favor- 

 able hormone-constellation, which may overcome the damage caused by a 

 certain degree of incompatibility between the individuality differentials of 

 host and transplant. Likewise in strain A, in which there is also a difference in 

 the constitution of the individuality differentials between mice belonging to 

 the same and to different litters, the removal of the ovaries somewhat im- 

 proved the results. 



While in strains New Buffalo and AKA transplantations into sisters seemed 

 to have an advantage over transplantations into different litters, ovariectomy 

 did not appear to be of much significance, the improvement, at best, being only 

 slight. Transplantation into males gave at least as good results as transplanta- 

 tion into female mice, and after transplantation into older mice there was in 

 quite a number of cases a survival of the ovarian structures. Furthermore, 

 given favorable relations between the individuality differentials of host and 

 donor, ovarian transplants may remain alive in the host for a length of time 

 which is so great that the age of the ovary, or of some of its surviving struc- 

 tures, may exceed the average age of the individuals belonging to a certain 

 strain. Thus, in a nonovariectomized mouse, young corpora lutea were found 

 in a transplanted ovary which had remained in the host for about 18 months; 

 here, lymphocytic infiltration had occurred. Also in strain A it was not diffi- 

 cult to recover well preserved ovaries which had been transplanted for half a 

 year or longer. Moreover, in strains A and C57, ovaries were successfully 

 transplanted into 12 to 20 months old female mice. In strain C57, donor and 

 host belonged to different litters and the hosts had not been ovariectomized. In 



