228 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



did not behave in the same way ; similarly, in urodeles some differences have 

 been noted; thus, transplantations of the ovaries from Triton alpestris to 

 Amblystoma tigrinum succeeded, while in the reciprocal transplantation the 

 graft exerted a toxic effect on the host. However, it is possible that in this 

 instance we have to deal not with the direct effect of the organismal differen- 

 tials, but with specific toxic substances, the production of which is limited 

 to certain organs. 



Also, heterotransplantations of testicle were successful in some species of 

 Triton (Koppanyi). But if certain organs are grafted with greater difficulty, 

 then it is possible to make homoio- and auto-, but not heterotransplantations. 

 Thus, according to Kurz, limbs can be homoiotransplanted in adult Triton 

 and even regeneration may take place in autogenous as well as in homoiogenous 

 grafts of this kind ; but heterotransplantation does not succeed. Similar obser- 

 vations have been made by Mathey in the case of transplantation of the eyes 

 in Salamander larvae and in adult Tritons. Under these conditions even 

 autotransplantation succeeds only in a small minority of cases, and still greater 

 difficulties are encountered in the case of homoiotransplantation. In Triton, 

 the presence of a functioning spleen, or of substances given off by this organ, 

 may be an unfavorable factor in the transplantation of this tissue. Ehrenpreis 

 accomplished, therefore, a homoiotransplantation of spleen only in urodeles 

 in which the spleen had previously been extirpated; but even in this case 

 autotransplantation seems to have been preferable to homoiotransplantation 

 (Jolly and Lieure). 



If we compare the range in which transplantations are possible in anurans 

 and in urodeles, we find a greater restriction in the former. Welti succeeded 

 in homoiotransplantation of the ovaries in Bufo vulgaris, while transplanta- 

 tions into different races failed. The successfully transplanted ovaries gave 

 off hormones which modified certain secondary sex characters in the host. 

 Meyns observed that the testicle is readily homoiotransplanted in immature 

 frogs, but can be heterotransplanted only in exceptional cases. In adult frogs 

 even homoiotransplantation does not produce as favorable results as autotrans- 

 plantation, an observation which indicates that also homoiodifferentials may 

 exert here an injurious effect on tissues. Furthermore, this investigator noted, 

 in accordance with the findings in the case of mammalian organs, that different 

 constituents of an organ may differ in the degree of sensitiveness which they 

 manifest; the efferent ducts of the testicle were less sensitive to the injurious 

 effects of transplantation than the generative cells proper. As in Tritons, 

 so also in anurans a specific hormone may inhibit the successful transplantation 

 of an organ with an internal secretion. Thus transplantation of the testicle was 

 possible neither in normal males nor in normal females, but only in castrated 

 animals. Which phase in the process of transplantation is here affected by the 

 internal secretion, whether it is the healing-in of the graft or its subsequent 

 preservation, is not clear from the data on hand; nor do we know whether 

 the destruction of the transplant takes place directly under the influence of 

 the injurious bodyfluids of the host, or through the mediation of the host 

 lymphocytes and connective tissue cells. 



