ON RESULTS OF REMOVAL AND TRANSPLANTATION OF OVARIES. 597 



while the follicles had disappeared, or the greater part of the graft might be composed 

 of luteal tissue alone. 



It will further be seen that the cases of transplantation classed as successful are 

 fewer in heteroplastic than in homoplastic implantation. Of our two successful hetero- 

 plasts, one was a graft into a rat of the same litter, while the other was possibly but not 

 certainly a similar case. 



The maintenance of the histological characters in successful grafts points to retention 

 by them of function, and further evidence of their functional integrity is derived from 

 the fact that the constituents of the graft varied according to the period in the repro- 

 ductive cycle at which the animal was killed. At the commencement of the breeding 

 season large follicles were found in the graft ; at a later period corpora lutea were 

 present. It is to be presumed, therefore, that the grafts passed through the same phases 

 of functional activity as normal ovaries. 



Condition of Uterus after Ovarian Transplantation. 



We examined the histological condition of the uterus in those cases where the ovaries 

 had been removed and transplanted to another position in the body. The appearance of 

 the uterus was found to bear a relation to the microscopic structure of the graft. If the 

 latter had retained unaltered, or with little alteration, the typical characters of ovarian 

 tissue, the uterus was found undegenerated ; thus in Experiment 8 of our series of homo- 

 plasts (p. 596), in which the ovaries had been transplanted for six months, the uterus was 

 normal. If, however, the graft had failed to " take," the uterus exhibited undoubted 

 evidence of degeneration. Where the graft had been successful, on examining it and 

 the uterus post mortem we found that each organ had the appearance appropriate to 

 the time of year and stage of reproductive cycle at which the animal was killed. Thus 

 in one case where the graft had met with some measure of success, and the animal was 

 killed at the beginning of the breeding season, the ovary contained large follicles and 

 the uterus was in the condition which has been described as the recuperative stage of 

 the cestrous cycle. 



In the case of transplantation from rat to rat, uterine degeneration was found, as in 

 homoplastic implantation, to be arrested by a successful graft. 



General Conclusions. 



In our previous paper (1905) we supplied evidence in support of the view that heat 

 and menstruation are induced either directly or indirectly through the activity of an 

 internal secretion or hormone arising in the ovaries, while we adduced further evidence 

 that the corpus luteum provides a secretion which assists in the nourishment of the 

 embryo during the first stages of pregnancy. In the present paper we show that the 

 existence of ovarian tissue is an essential factor in normal uterine nutrition ; and further, 

 that the nature of the ovarian influence upon the uterus is chemical rather than nervous, 

 TRANS. ROY. SOC. EDIN., VOL. XLV. PART III. (NO. 21). 84 



