The whole method of skin grafting is based on the fact that if epithelium be removed from any portion of the body and planted on favorable soil elsewhere it will take root and grow, reproducing only itself and no other kind of tissue. It is closely analogous to sewing seed upon a favorable soil, or even to sodding. Furthermore it is not necessary that epithelium be furnished from the individual upon whom it is to be implanted; it may come from another of the same species or even from a different species. Thus the skin of the frog has been used for grafting upon human beings, and even the lining membrane of the egg. Nor is it necessary that the epithelial cells should be apparently alive when thus employed. Very thin shavings of human skin which have been dried, or have been kept from decomposing by some antiseptic, have been successfully used; nevertheless the ideal method consists in taking what is needed from the individual who needs it. The term skin grafting is now applied to the employment of very thin layers of the epidermis, _i. e._, as thin as can be shaved off with a sharp razor, and it does not apply to the autoplastic methods of skin transplantation. Hamilton, of Buffalo, and Reverdin, of Geneva, a number of years ago independently discovered that minute particles of healthy skin might be implanted upon healthy granulations and that from such minute grafts epithelium would be produced and a fresh epidermal covering be afforded. This method was in use for years and was a great advance on what had previously been done. Then Hamilton, of Edinburgh, suggested the use of thin slices of clean sponge, in order that thereby a trellis might be offered for the growing and climbing granulation tissue; this served a good purpose in many cavities. But the greatest advance came when Thiersch demonstrated that large areas might be covered with skin shavings, and that thus in a few days there would be accomplished that which took weeks or months by older methods. His original plan comprehended only the use of these grafts upon granulation tissue; later it was found that they might be applied to fresh raw tissue, even to denuded bone. Thus originated the so-called _Thiersch method of skin grafting_.