HORMONES AND INDIVIDUALITY DIFFERENTIALS 147 



lopian tube in rabbits (Guerriero), and of vagina in guinea pigs (Reynaud), 

 show that stimulating hormones influence here, also, the growth processes 

 and size of the transplants, without being needed, however, for the survival 

 of the latter. In regard to the transplantation of ovaries, according to Lip- 

 schiitz the total number of preserved follicles in the transplants is greater in 

 ovariectomized than in non-ovariectomized animals, an effect which was ob- 

 served however only under certain conditions and not as a general rule in our 

 experiments ; moreover, the interaction between individuality differentials 

 and hormones were not considered by this investigator. Numerous experi- 

 ments have demonstrated the effects of the anterior hypophysis on the ovaries 

 and testicles, demonstrating the significance of the hormones given off by this 

 organ for the growth and for the functioning of various constituents of the 

 sex glands, and these influences extend also to the transplanted sex glands 

 (Engle, Moore and Price, Takewaki, Bayer and Wense, and others). If we 

 consider the results of these investigations as well as of our own, on which 

 we have already reported, and those of Pfeiffer, we may conclude that the 

 following conditions are involved in the survival and growth of transplanted 

 sex glands: (1) The relation between the individuality differentials of host 

 and transplant (genetic factors) ; (2) The age of the transplant; the trans- 

 plantation of the sex glands of newborn animals seems to succeed better than 

 that of older animals, at least in the case of the testes; (3) The removal of 

 the sex glands of the host; this favors, in the first place, the growth and 

 function of the transplant, and it may, secondarily, affect also its survival ; it 

 seems to be a more important factor when the hosts are older animals ; 

 (4) Transplantation to the opposite sex ; there are some indications that under 

 certain circumstances this may be a more favorable procedure than trans- 

 plantation to the sex of the donor. The order in which these factors are cited 

 indicates probably also their relative importance, the first one being the most 

 important. 



The following are the principal conclusions concerning the relation of varia- 

 tions in hormone actions to the fate of transplants. The effects of administra- 

 tion of hormones to the host, or of a diminution in the amount of hormones 

 in the host on the fate of transplanted organs varied in different organ trans- 

 plants and perhaps also in analogous organ transplants in different species. 

 They were moderate, slight, or perhaps entirely lacking in some experiments 

 with thyroid, parathyroid and ovarian grafts, or they were quite pronounced, 

 especially in the case of adrenal grafts. They were found in transplants of 

 endocrine organs, as well as in transplants of other organs or tissues on which 

 hormones may exert a certain influence. Such effects may be noticeable after 

 autotransplantation as well as after homoiotransplantation. In the former, it 

 may be assumed that continued hormone stimulation prevents the gradual 

 atrophy which might ensue due to the combined effect of lack of function of 

 the transplanted organ and of injurious conditions existing at the site of 

 transplantation. Homoiotransplanted organs, as a result of the increase in 

 growth momentum acquired with the aid of hormone action, are enabled, to 

 some extent, to overcome the unfavorable conditions caused by disharmonious 



