This may be caused by traumatism, such as incised punctured or bruised wounds. Wounds inflicted by the goad, by horns, and even by the yoke in cattle must be looked on as factors. It occurs from obstruction of the salivary ducts by calculi, or by grains, seeds, or pebbles introduced from the mouth; from their irritation by the beards of barley and other plants (brome, rye, wheat, etc.); and from the localization in the gland of specific inflammations like strangles, pyæmia, canine distemper, tuberculosis and pharyngitis. In most of these cases infective microbes are prominent factors. They enter with penetrating bodies from the skin; they extend through the weakened and debilitated tissues in bruises; they penetrate the Stenonian duct with the various foreign bodies from the mouth; irrespective of foreign objects they make their way up the duct by continuous growth from the buccal orifice; in case of calculus or other obstruction their extension is favored by the local congestion and debility and by the stagnation of the saliva above the point of arrest. When present these microbes even favor the deposition of the salivary salts and formation and increase of calculi so that the affection may advance in a vicious circle, the microbes favoring calculus and the calculus favoring the increase of microbes. _Symptoms._ In the horse in particular there may be premonitory symptoms of fever, dullness, heat of the mouth, ptyalism, slow and imperfect mastication, and the retention of food in the cheeks. The Stenonian duct becomes swollen and painful. The parotid becomes hard, hot, tender, and is surrounded by a softer pitting infiltration which may extend down around the entire throat, and even along the intermaxillary region to the chin. When the canal is obstructed it may stand out as a thick rope-like resilient swelling extending around the lower border of the jaw and upward toward the cheek as far as the point of obstruction. When one parotid only is involved, the contrast with the other is quite marked. The head is extended and carried stiffly. When the nose is depressed, or when the head is turned to one side or the other, the patient gives evidence of suffering from compression or stretching of the inflamed region. The breath and mouth exhale an offensive odor, determined by the decomposition of mucus and of the retained food products. Among remote effects may be named dyspnœa and threatened suffocation from pressure on the pharynx and laryngeal nerves, and facial paralysis from pressure on the seventh nerve.