TRANSPLANTATION AND INDIVIDUALITY. 147 



which later attract the lymphocytes. In addition there occur ab- 

 normal reactions in the transplant which render impossible the 

 normal restitution of pigment in the graft. Some of these 

 changes in the transplant may take place so soon after trans- 

 plantation that the conclusion suggests itself that in this case an 

 incompatibility between the graft and the body fluids of the host 

 interferes directly with those tissue reactions on which depends 

 the healing in of the graft and the reestablishment of the normal 

 pigmentation. How far these primary changes in metabolism of 

 the graft injure the transplant directly and to what extent they 

 act possibly through induced changes in vascularization of the 

 graft still remains to be determined. It is, however, more prob- 

 able that the incompatibility between body fluids and graft leads 

 to a direct interference with the transplant. 



TRANSPLANTATION OF THYROID AND KIDNEY 



If we transplant thyroid gland into the subcutaneous tissue 

 only the peripheral gland tissue survives, the center of the graft 

 being ill nourished in the first few days following the detachment 

 of the gland from its soil dies. The peripheral gland acini pro- 

 liferate soon after transplantation. After autotransplantation 

 blood and lymph vessels grow through this ring of well-preserved 

 and temporarily growing thyroid tissue into the necrotic center, 

 and especially in the peripheral part of the latter they form a ring 

 of vessels which is very noticeable ; from here vessels penetrate 

 into the center of the necrotic material. They are accompanied 

 by a relatively limited number of fibroblasts which at the inner 

 aspect of the thyroid ring form a loose, almost myxoid connective 

 tissue around the blood and Imyph vessels, a tissue not unlike that 

 found in certain stages of development in the embryo. Further 

 removed from the thyroid ring, in the real center of the necrotic 

 material, there may be produced a nucleus of dense fibrous tissue. 

 But its existence is only temporary after autotransplantation. 

 Sooner or later the blood and Imyph vessels and fibroblasts pene- 

 trate into it, absorb it and substitute for it the same kind of loose 

 vascular connective tissue ; this again gives way more and more 

 to the peripheral real thyroid tissue. As a result of the absorp- 

 tion of the central connective tissue and of the marked develop- 



