At the period when transplantation was systematically performed, the operators kept themselves supplied with an assortment of dried teeth, _i.e._, sound teeth, obtained generally from the dead subject, to make use of in case the tooth to be transplanted should not prove adaptable to its new abode. The process is not spoken favourably of, as the results were mostly unsatisfactory, but at times such teeth became perfectly firm, and even resisted the greatest efforts at their removal. We can hardly for one moment suppose that teeth in the condition these were could have ever become attached to a living alveolo-dental membrane, and the difficulty of accounting for this firmness would have been great indeed, had it not been already solved for us. In Langenbeck’s Archiv. für Chirurgie, vol. iv., is a paper on “The Replantation and Transplantation of Teeth,” by Dr. A. Mitscherlich, which deserves to be better known, and which, apparently, cannot have come under the observation of those who recently contributed to the _Lancet_ on the subject, the excuse for which is less, since it has been translated into English.[2] The author, in addition to much interesting and original matter, records the following experiment. In the upper jaw of a dog of a year old, Dr. Mitscherlich inserted into the socket of an incisor he had removed, a similar tooth taken from a dog’s skull, and which he retained in _situ_ by means of a silver wire passed through a hole in the tooth, and a hole bored through the alveolar process of the jaw. “After six weeks the dog was killed, having been given during the last few days three grains of picronitrate of potash three times a day; the carotids were immediately injected. The muscles, like the gums, were coloured yellow: neither, however, in the implanted tooth nor in the sound ones was any alteration of colour perceptible. The silver wire was porous, and no longer held the tooth; it was removed. The tooth was quite firmly seated, and could not be moved in the least by the fingers. The gums, as in the remaining teeth, were accurately applied both to the alveolar process and also to the tooth itself, and nowhere could any alteration be found in it. The tooth was sawn through lengthways, together with the upper jaw, with a fine saw, so that the pulp cavity was laid bare in its whole extent. The latter was only filled with a little detritus, and no trace of the pulp was discoverable; none of the injection, too, had been forced into the cavity. The tooth was everywhere most intimately connected with the surrounding parts, and suppuration showed itself nowhere. Of the periosteum, on the other hand, there were only in a few places some small remains discoverable. On the posterior surface of the tooth two small cavities were visible; the larger of which lay more towards the point of the fang, and extended to the pulp cavity; they were filled with a soft substance, and their walls appeared roundish.