252 Transplantation. 



inserted into a split in the comb of the capon, becoming attached 

 by growth in this situation (Aldrovandi, Worm, in the seventeenth 

 century ; Baronio in 1804). The spur, if engrafted when very young, 

 may grow in this new and well vascularized base to become several 

 inches in length ; and sometimes tlie central bony core grows, carry- 

 ing over it a horny epidermal covering, so as to produce two spurs 

 growing alongside of each other. Embryonic tissue with undiffer- 

 entiated cells shows a moderate capacity for growth when trans- 

 planted. Fere grafted bits of blastoderm (forty-eight hours) and 

 the eyes of six to eight day chick embryos under the skin of young 

 chickens and noted that the mesoblastic tissue underwent more or 

 less further development to the production of small tumors (con- 

 taining cartilage and in one case small feathers), which persisted for 

 about a month. Such a result has an important bearing in explain- 

 ing the conditions involved in the origin of tumors. 



Transplantation of tissues is more difficult in mammals. The 

 possibility is best realized when the part to be transplanted can 

 retain connection with its neighboring structures by a bridge, as 

 where a flap of skin is twisted around and stitched to an adjoining 

 part, the nutrition of the flap being at least partially maintained 

 (as in the operation of rhinoplasty in man). The result in trans- 

 planting unattached and completely separated bits of the corium 

 and of the epiderm is not at all uniform. In this procedure, recom- 

 mended by Reverdin and Thiersch for quickly obtaining an epi- 

 dermal surface over large superficial wounds, which has been tested 

 by many investigators, especially by ]\Iarchand and Enderlin experi- 

 mentally, the transplanted fragments adhere by a layer of coagulated 

 blood and lymph to the fresh or granulating wound. Later on there 

 occurs an active vascular and cellular proliferation in the substruc- 

 ture, the fibroblasts and angioplasts of the latter growing up into 

 and through the engrafted cuticular fragment, which is actually re- 

 placed by the new connective tissue. The epithelium desquam- 

 ates and only to a very slight extent is the graft the starting point 

 for the formation of the new layer of skin. In reality the new 

 graft is more like a piece of plaster, beneath which the formation 

 of new elements from the adjacent structures may take place with 

 facility (Diirk). For success in such transplanations the size of 

 the bit of tissue transplanted should be taken into consideration 

 (even particles no larger than a pea may disintegrate in the central 

 part because too much time is required to afford them proper nour- 

 ishment), as well as the question whether the base of implantation 

 affords thoroughly favorable conditions for nutrition. For example 



