HETEROTRANSPLANTATION 



125 



but some capillaries were noted between some of the acini. Lymphocytes were 

 seen only occasionally in these places, being found especially where fibro- 

 blasts had invaded the transplant or were active around it, as well as in the 

 capsule of the graft surrounding blood vessels. On the whole, heterotrans- 

 planted thyroid as such did not attract lymphocytes to any marked extent; 

 indeed, these cells and the connective tissue contributed only secondarily and 

 to a minor degree to the destruction of the graft. 



In general, the connective tissue of the heterotransplanted thyroid became 

 fibrous during the second week. The number of lymphocytes in the transplant 

 itself was small, but in the course of the second week a marked accumulation 

 of lymphocytes could take place in the surrounding capsule and at some dis- 

 tance from the thyroid proper; lymphocytes collected also in the fibrous tissue 

 resulting from the organization of the necrotic material. 



Heterotransplantation of kidney tissue into various species, studied in 

 association with M. H. Myers, on the whole gave results similar to those 

 found after heterotransplantation of skin and thyroid, but the duration of 

 mitotic activity and the survival seemed to be slightly longer in the case of 

 thyroid and kidney than of skin. A comparison of the period of survival and 

 of mitotic activity in these various series of experiments is shown in the fol- 

 lowing tables. 



TABLE I 



Transplantation 

 of Skin 



Latest Time at 



Which Mitoses 



Were Seen 



Time of Survival of 



Transplanted Skin 



Tissue 



Pigeon 

 Pigeon 

 Pigeon 

 Pigeon 

 Guinea 

 Guinea 

 Guinea 

 Guinea 



to chicken 

 to guinea pig 

 to rabbit 

 to frog 

 pig to rabbit 

 pig to dog 

 pig to pigeon 

 pig to frog 



TABLE II 



Transplantation of 

 Thyroid 



Latest Time at 

 Which Mitoses 

 Were Seen 



Time of Survival of 



Transplanted Thyroid 



Tissue 



Guinea pig to rat 

 Rabbit to rat 

 Rabbit to guinea pig 

 Cat to rat 



9 days 



9 days 



6 days 



1 1 days (a few mitoses) 



9 days 

 11 days (in 1 of 3 pieces) 

 8 days 

 14 (18?) days 



Heterotransplantation of cartilage. After heterotransplantation of cartilage 

 together with the adjoining fat tissue, connective tissue of the host invaded 

 and largely replaced the fat tissue, but it was also able to invade the cartilage, 



