Among the lesions of the diaphragm, none has passed into the literature under more synonyms than the condition commonly called ``eventration.'' Since 1849, when Cruveilhier introduced his conception of the disease under this term, the names: "dilatation," ``relaxation'' (Wieting), "insufficiency" (Franck), "high position," "elevation" (Griffin), have been used to designate a pathological state of the diaphragm, characterized by a general expansion of one half of the organ, allowing the abdominal viscera to be displaced upward into the thoracic cavity. The diaphragm is greatly thinned as well as distended, but its three layers remain intact, and there is no solution of its continuity. In this essential respect, the condition is different from hernia of the diaphragm, which, whether true or false, depending on the presence or absence of a hernial sac, consists of a localized opening in the sheet of the diaphragm, through which the abdominal viscera pass