If, then, we could discover the conditions that would preserve the bone tissue, in connection with the dentine, from undergoing decalcification, we might, with every prospect of success, transplant dead teeth, but which, as at present carried out, invariably, we believe, eventually, suffer the fate of ivory pegs introduced into the extremities of bones in disunited fractures. Indeed, this result, although more slowly effected, appears nearly always to follow in those cases where the transplanted or replanted tooth has lost much of its alveolo-dental membrane; whether the excising of a portion of the fang, as advocated by Magitôt, will prove beneficial or otherwise, remains to be seen. Porcelain teeth having indentations in their fangs have been suggested, first, we believe, by Mitscherlich,[3] and again by a recent writer in the _Lancet_. The former actually attempted two cases, and with the success we should have anticipated, for when after four or five weeks the caoutchouc splint which retained them in _situ_ was removed they immediately followed the splint and fell out. “Ossification had not taken place; the entirely heterogeneous mass of stone had acted as a foreign body, produced granulation and suppuration, and so prevented union.” Footnote 3: _Op. Cit._ In conclusion, we think enough has been stated to show that transplantation or replantation of living teeth, or at all events, of teeth having living alveolo-dental membrane may be exceptionally carried out with benefit to the patient; if the chances of permanent success be not very great the chances of injury are, we believe, small, and have been greatly exaggerated. No such case has come under our observation, but then in all we have witnessed, the transplanted or replanted tooth has never been ligatured or otherwise forcibly retained in its alveolus. We believe many of the cases of failure, as probably those also of bone exfoliation, arose from this procedure. A tooth, after either operation, although at the time perfectly adjusted to its proper position, becomes, after a day or two, elongated from its socket and less firm; the result of effusion into the alveolo-dental membrane and about the tooth; as this material becomes organized it forms, no doubt, the medium of union between the dental and alveolar portions of that membrane. At all events, after a week or so the tooth again recedes into its socket, and as it does so becomes firmer and less sensitive to pressure; if our view be correct, the employment of a ligature or forcible retention of the tooth can only be objectionable. A very different matter, however, will be the adjustment of a plate contrived so as to protect the transplanted or replanted tooth from violence or pressure until its attachment is ensured. Mercurial Amalgams. BY M. G. CUNNINGHAM.