Because there is a wide range of printed material available on diseases of the salivary glands, it is a great temptation in discussing this problem to quote from numerous references and to pose the points of view of many workers who have made creditable contributions to the literature. I wish it were possible to pay tribute to the authors who have preceded me and to do justice to this subject by expressing their critical judgments, but space will not permit such a comprehensive review of this topic. While the secretory glands that discharge their products into the oral cavity are recognized to be the parotid, submaxillary and sublingual glands, the glands of Blandin and Nuhn, the palatal glands, the Moore glands and numerous small mucous glands scattered over the buccal mucous membrane and floor of the mouth, I shall limit my discussion to but one structure, namely the parotid gland.