Numerous investigators have contributed to the knowledge physicians have of the anatomy, physiology, development and pathology of the tube which Eustachius described in 1563 and which has since borne his name. That the function of the tube is to equalize the pressure of air in the tympanum all students agree, but there is no such universal agreement as to how the equalization is accomplished and just how the tube is opened and closed. Some of the explanations of the way in which the tube functions are the following: (1) The tube is opened by the tensor veli palatini muscle and closed by the levator; (2) it is closed by the tensor and opened by the levator; (3) it is opened by both the tensor and the levator; (4) it is closed by both the tensor and the levator, assisted, perhaps, by the superior constrictor of the fauces; (5) it is