168 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



homoiotransplantation of a leg from one fox terrier to another was successful. 

 The animal lived 22 days after the operation, all the tissues had healed, 

 there was no ulceration, and even regeneration had taken place when a toe in 

 the grafted limb was injured. A callus united the bone ends. In later experi- 

 ments, Carrel observed, in a homoiotransplanted kidney, secretion of urine 

 for 8 days, but the animal died after ten days. After heterotransplantation 

 of kidney, the transplant was absorbed a few weeks later. Lexer did not 

 find it possible to keep a transplanted leg in a dog alive for longer than 

 three weeks, and thrombi were found to develop in the transplanted tissues. 

 Giani however was more successful and a leg autotransplanted by him lived 

 for three months; there was good union but no active motion. 



However, the results of careful microscopical studies made by Borst and 

 Enderlen on transplanted blood vessels showed that only autogenous trans- 

 plants survive for any length of time; homoiogenous and also heterogenous 

 transplants gradually die and are replaced by the tissues growing into the 

 transplant from the adjoining host tissues and wandering cells of the host 

 may accumulate at the point of union. In this place thrombi form more 

 frequently after homoio-, and especially after heterotransplantation, than 

 after autotransplantation. Autotransplantation of thyroid and kidney by 

 means of blood vessel anastomosis may succeed ; but after homoiotransplanta- 

 tion, hemorrhagic infarction, necrosis, or atrophy and fibrosis of the grafted 

 organ occur. Likewise Williamson found that the homoiotransplanted kidney 

 functioned only for a few days, while autotransplantation was successful, 

 except that atresia of the ureter could cause hydronephrosis and infection of 

 the graft. In case of syngenesiotransplantation of kidney within the same 

 litter of dogs, kidney function was maintained for 26 days. As to the length 

 of time during which homoiotransplantation of blood vessels may succeed, 

 Ingbrigtsen observed, in cats, that the carotids may remain alive for three 

 months; among 14 experiments, 8 satisfactory results were obtained. There 

 was no thrombosis in these latter cases, but this did occur in the other six. 

 Elastic fibers of media were normal, likewise muscle cells were well pre- 

 served, while intima and adventitia were thickened. 



The interpretation of these investigations, as far as they are of interest in 

 the analysis of the individuality differentials, suffers from a lack of distinc- 

 tion, in the reports of the authors, between strict homoiogenous and 

 syngenesious (brother-sister) relationship in many of the experiments. Also, 

 too great a reliance was placed on a mere macroscopic examination of the 

 transplant, while careful microscopic studies of successive stages in such 

 transplantations were omitted. Furthermore, these experiments were made 

 largely from the viewpoint of the surgeon, who is interested in the possibility 

 of using such methods of transplantation in patients. Notwithstanding the 

 difficulties involved in a correct interpretation of the results of these investi- 

 gations, and of other similar ones, which need not be discussed, it may be 

 concluded that there is a marked difference between the fate of autogenous, 

 homoiogenous and heterogenous parabiotic transplants. The former may live 

 indefinitely if unfavorable conditions of a more or less accidental kind can be 

 avoided, whereas, the two other types of transplants in all probability die as a 



