GRAFTING 391 



dilation properly maintained, nothing more than simple 

 healing is required to restore the usefulness of the part 

 or member. When the tissue fragment is too small to 

 permit of vascular suturing and must temporarily 

 derive its nourishment by imbibition from the surround- 

 ing tissues, it becomes more difficult to effect transplan- 

 tation of considerable masses. Before Nature can 

 provide new vessels for maintaining it, the replaced tissue 

 commonly dies and undergoes mortification. Tissues 

 provided with free capillary plexuses most easily survive, 

 provided they are not composed of highly specialized 

 and easily damaged elements. In injuries of the human 

 body large fragments of the facial tissues torn loose, but 

 not entirely away from their attachments may be success- 

 fully replaced if not seriously infected. Fingers almost 

 severed or torn away may be replaced, and in a few 

 cases fingers entirely cut off have been replaced, carefully 

 sutured, and have successfully united. There is, how- 

 ever, no certainty about the results in such cases, and 

 the surgeon congratulates himself and his patient when 

 such operations terminate in recovery. An extracted 

 tooth restored to its socket will again grow fast and 

 become as good and useful as before, though its nutrition 

 is usually imperfect. New blood vessels grow into the 

 pulp cavity, new nerve fibres find their way into it, and 

 the restoration is fair. 



Among the higher plants, the amputation and careful 

 replacement of parts in such a cautious manner as to 

 secure continuity of the vascular bundles is usually 

 followed by the continued life of the graft, precautions 

 being taken to provide artificial support until firm union 

 of the fragments has been secured. 



Among the lower orders of animals grafting becomes 

 correspondingly easier without vascular suture. Thus 

 when the tail of a tadpole or the leg of a salamander is 

 removed and then replaced, some means being provided 

 for holding the parts in place, union readily takes place 

 and the usefulness of the part is restored. 



