One of the most interesting chapters of Serre’s great work is the one in which he treats of affections of Highmore’s cavity.[527] He speaks at length of the anatomy of the maxillary sinus, of its relation to the teeth situated below it, of the various modes in which the diseases of the antrum are produced, of their symptoms and treatment. He passes in review the various operative methods, and finds that in general the Cowper-Drake is the one to be preferred to all the others. He says that to open the sinus the simple extraction of a molar suffices in the greater number of cases, the trepanning of the alveolus not being generally necessary. J. ARNEMAN, in 1766, published at Göttingen a synopsis of surgical instruments[528] that deserves mention in so far that the dental instruments of that time as well as those of earlier periods are therein taken into account with sufficient exactness. A. F. HECKER attributed the accidents of difficult dentition to a special alteration of the saliva caused by the irritation deriving from the erupting teeth. In these cases the saliva is supposed by him to acquire a high degree of acridness and to become almost similar to the poison of rabies. Departing from this theory, the author declares it to be necessary to mitigate the irritation produced on the gums and other parts of the mouth by the altered condition of the saliva, as well as to modify the quality of the saliva itself and to promote the elimination of the same from the body by emetics and aperients. According to him, liquid carbonate of potash administered in drops, together with syrup of poppy heads, manna, etc., is a most useful remedy, having specially for its effect to diminish the acridness of the saliva. Besides this remedy, the author extols the use of blisters behind the ears, as also of tepid baths, which calm pain and spasms, favor the excretions, and procure repose and sleep. He rejects the incision of the gums as altogether useless, and is most opposed to the use of opium, which he states renders children liable to apoplexy.