this particular color of cleansing cloth was recommended is not quite clear. He recognized, however, that cleansing of the teeth properly often became impossible by any scrubbing method, no matter what the dentifrice used, because of the presence of what we call tartar and what he called hardened limosity or limyness (_limosite endurcie_). When that condition is present he suggests the use of rasps and spatumina and other instrumental means of removing the tartar. Evidently he did not believe in the removal of the teeth unless this was absolutely necessary and no other method of treatment would avail to save the patient from continuous distress. He summarizes the authorities with regard to the extraction of teeth and the removal of dental fragments and roots. He evidently knew of the many methods suggested before his time of removing teeth without recourse to instrumental extraction. There were a number of applications to the gums that were claimed by older authors to remove the teeth without the need of metal instruments. We might expect that Chauliac would detect the fallacy with regard to these and expose it. He says that while much is claimed for these methods he has never seen them work in practice and he distrusts them entirely. The most interesting phase of what Guy de Chauliac has to say with regard to dentistry is of course to be found in his paragraphs on the artificial replacement of lost teeth and the subject of dental prosthesis generally. When teeth become loose he advises that they be fastened to the healthy ones with a gold chain. Guerini suggests that he evidently means a gold wire. If the teeth fall out they may be replaced by the teeth of another person or with artificial teeth made from oxbone, which may be fixed in place by a fine metal ligature. He says that such teeth may be serviceable for a long while. This is a rather curt way of treating so large a subject as dental prosthesis, but it contains a lot of suggestive material. He was quoting mainly the Arabian authors, and especially Abulcasis and Ali Abbas and Rhazes, and these of course, as we have said, mentioned many methods of artificially replacing teeth as also of transplantation and of treatment of the deformities of the dental arches. On the whole, however, it must be confessed that we have here in the middle of the fourteenth century a rather surprising anticipation of the knowledge of a special department of medicine which is usually considered to be distinctly modern, and indeed as having only attracted attention seriously in comparatively recent times. After Guy de Chauliac the next important contributor to dentistry is Giovanni of Arcoli, often better known by his Latin name, Johannes Arculanus, who was a professor of medicine and surgery at Bologna and afterwards at Padua, just before and after the middle of the fifteenth century, and who died in 1484. He is famous principally for being the first we know who mentions the filling of teeth with gold.