He, too, made the administration of purgatives or bloodletting precede the extraction of a tooth. Plateario has, however, the merit of having introduced the sitting position for operations on the teeth, whilst preceding surgeons made the patient lie in a horizontal position, or held his head steady between their knees, as may be read in Abulcasis and in other writers. Besides, he recommends taking care, when the extraction of a tooth had to be performed, that the surrounding air should be pure; perhaps because he thought that when operating in a place where the air was tainted, complications might more easily arise, on account of contagious substances reaching the inside of the wound; or perhaps because he judged, not without reason, that certain accidents, such as syncope, could more easily happen, and were more dangerous in a tainted atmosphere than in the midst of pure, vivifying air. After the operation, he prescribed astringent mouth washes. Against dental worms, whose existence no one at that period doubted in the least, Plateario recommended various remedies, chiefly under the form of fumigations; and among these latter, those performed with burnt opium. Against ulcerations of the gums and mouth he commended the use of wine and aromatic substances. An excellent remedy was also, according to him, lime dissolved in very strong hot vinegar, and mixed, after complete evaporation of the liquid, with a fourth part of orpiment. GIOVANNI OF ARCOLI (in Latin, _Joannes Arculanus_), professor at Bologna and afterward at Padua (who died in 1484), wrote a commentary on a celebrated book of medicine, which Rhazes had dedicated to the glorious King Almansor, great patron of science and art.[263] In this most valuable work of Arculanus there are several chapters relative to diseases of the teeth; and this subject is treated rather fully and with great accuracy. The author, first of all, treats of the anatomy and physiology of the teeth; he, however, falls into many errors, for instance, in regard to the number of dental roots. (“The first six teeth of the upper jaw have only one root; the first six of the lower not more than two; the molars of the upper jaw have three; those of the lower generally only two in like manner; the _neguezid_[264] of the upper jaw have four roots, but the two lower neguezid have only three.”) According to him there is not the least doubt that the teeth grow during the whole lifetime, thus repairing the continual waste caused by use; and among other proofs he adduces that, whilst in the old all other organs shrink and waste away through lack of nourishment, the teeth, on the contrary, show very frequently an increase in length.