TRANSPLANTATION OF PIECES OF TISSUE 251 



plant by grafting embryonal tissues into the eye socket of amphibia after 

 its contents had been removed. However, even under these conditions the 

 transplant did not develop as a mosaic, but underwent various irregular 

 transformations into other tissues, presumably under the influence of the 

 host ; thus ectoderm could differentiate here into neural or mesodermal parts, 

 in contrast with what happened in salt solutions in vitro, where ectoderm 

 merely proliferated and formed epidermis. This result applied to tissues 

 transplanted at early stages of their development; if farther advanced tissues 

 were used, the more fixed the organ differentials were at the time of trans- 

 plantation, the more frequently normal organs were produced. Diirken called 

 this method "interplantation" ; it represents a condition intermediate between 

 the ordinary transplantation and tissue culture in vitro. Such experiments 

 were carried out in anurans as well as in urodeles, but there was an interest- 

 ing difference between the interplantation in the anuran Rana and the 

 urodele Triton, in the former the homoiogenous material being toxic for 

 the host. Such toxic effects, consisting in hemorrhages and necrosis, were not 

 observed in case of syngenesiotransplantation. In urodeles, toxic effects were 

 lacking. It is noteworthy that in these experiments individuals were apparently 

 sensitive to toxic substances produced in their own species, although as a 

 rule a high degree of immunity exists in a species against its own poisons. 

 Kusche could successfully interplant early embryonal tissues which belonged 

 to different genera in urodeles; for example, Triton cells continued to dif- 

 ferentiate after transfer into larvae of Salamandra and Amblystoma; but if 

 the interplantation took place between different orders, such as between 

 Triton tissue and larvae of Rana fusca, or between cells of Amblystoma and 

 larvae of Hyla, the interplants were destroyed. We may assume that under 

 these conditions the bodyfluids of the host were toxic for the transplant, 

 owing to the divergence between the organismal differentials in host and graft. 



A number of investigators, beginning with Belogolowy, transplanted seg- 

 mented eggs, blastulae, gastrulae or neurulae, into the peritoneal cavity of 

 adult amphibia; or in other experiments the freshly fertilized eggs of 

 Axolotls were transplanted into larvae of the same kind, measuring 13 to 

 15 mm. in length. The transplants were able in certain cases to undergo 

 development, but this was abnormal, even after homoiotransplantation. How- 

 ever, if the relationship between host and transplant was very distant the 

 transplants usually died. Belogolowy did not observe a difference between 

 the results of homoiotransplantations and transplantations from Rana to 

 Pelobates and vice versa; but transplants from Rana to Triton were found 

 alive after one month only in exceptional cases. 



In two instances Janda observed that in axolotls fertilized eggs, when 

 transplanted to the peritoneal cavity of the same species, led, after three or 

 four months, to the development of embryonal formations, which were very 

 incomplete and structurally quite abnormal. Especially prominent in these 

 formations were epidermal cysts, masses of cartilage and nerve tissue pro- 

 ducing cysts; also, intestinal structures with glands and rudimentary kidney 

 and eyes were found. As in Diirken's interplantations into the eye socket, 



