The grafts do not become firmly fixed for nine or ten days, and it is well not to soak off the undermost layer of gauze for about two weeks.
The Method of Wolfe : Krause's Modi fication.—In this method grafts are em ployed which fill the entire defect, and which comprise the whole thickness of skin without including the subcutane ous tissue. In cutting the skin at least one-third must be allowed for shrinkage. Sutures are usually unnecessary and artificial heat is detrimental.
Wolfe's method has recently been modified and the technique improved by Krause, who employs spindle-shaped grafts so that the wound produced by their removal may be immediately closed. The strips of skin, cut into smaller pieces if desirable, are accurately fitted into the defect, which is to be closed. The op eration must be a "dry" one, and the raw surfaces of the skin should be handled as little as possible.
The Method of Hirschberg.—Believ ing that grafts subsist upon their con tained fluids until new vessels are formed, Hirschberg beats the skin with rubber tubing until it becomes engorged before making a transplantation. He employs the entire thickness of the cuticle, in cluding the subcutaneous fat. Sutures are often required.
Anomalies in Grafting.—Transplanta tion of mucous membrane may be made. It may be shaved off as in skin-grafting, —for instance, from the lips,—or it may be stripped off in its entirety.
More or less satisfactory results can be obtained by the use of shavings of callus from the palms of the hands or soles of the feet or from sections of corns. "Epi thelial rods" from warts have been suc cessfully used, as have also flakes of old, dried epidermis from various parts of the body; even "epithelial dust" scraped from the surface of the skin will often grow on a granulating wound. Deeper scrapings, drawing sufficient blood to form a paste, are said to he quite satis factory at times (Mangoldt).
Grafting from dead bodies or from amputated limbs has frequently been resorted to, but the danger of carrying disease cannot be disregarded.
Sponge-grafting is now seldom em ployed. Very thin slices of sponge are sterilized by boiling, and placed upon the raw surface. The material acts as a frame-work only for the granulations, and is soon absorbed.
The idea of grafting from animals is attractive, but the results are too un certain, and the method has largely fallen into disuse. Skin has been ob tained from frogs (abdomen), chickens (beneath the wings), pigs, dogs, cats, rabbits, guinea-pigs, etc. Cocks' wattles,
sections of the testicles of rabbits, and the lining membrane of eggs have also been employed.
Histology and Pathology.—The ex istence of epithelial grafts may be said to be, for a time, parasitic. In the course of about eighteen hours vascular connec tions begin to form, firm adherence tak ing place by the tenth day. Successful grafts soon become pinkish in color. New skin arising from large grafts which cover the entire raw surface becomes in time movable, but that produced from Reverdin-grafts remains immovable, ow ing to cicatricial tissue between the in dividual bits of cuticle.
Hairs may remain where transplanta tions of the entire thickness of the skin are made, but they are apt to become de formed or fall out.
But little contraction takes place in the Thiersch and Wolfe-Krause methods, but in the method of lieverdin contraction is apt to be considerable.
Exfoliation of epidermis may occur in any form of grafting, but this does not necessarily mean that the grafts are dead. A remarkable phenomenon in connection with Thiersch grafting is the readiness with which depressions fill up to a level with the surrounding skin, especially about the face.
Comparison of Methods.—The simplest is that of Beverdin, although the new skin is often little better than scar-tissue. It should be reserved for cases where the rapid closure of a granulating surface is desired without reference to anything else.
It may sometimes be expedient to graft from dead bodies or from amputated limbs; and occasionally use may be found for "epidermal scrapings," or for epidermis obtained from warts, corns, callosities, blisters, etc.; but one must not expect the results to be brilliant.
Thiersch grafting has a wider range of applicability than any other method, and its results are quite uniformly good, both functionally and cosmetically; but it must give way to the Wolfe-Krause proceeding where thicker skin is desired which more closely resembles the sur rounding integument.
It is seldom, if ever, desirable to em ploy the method of Hirschberg.
The skin of animals does not compare in vitality with that taken from a pa tient's own body or from some other person. It is seldom necessary to trans plant from mucous membrane, as ordi nary Thiersch grafting answers the same purpose in nearly all cases.