White and Sprague1have recently reproduced extracts from Fallot's original monograph (1888), some of which may be appropriately repeated: Of these cardiac malformations there is one which in frequency surpasses all others, since we have noted it in almost 74 per cent of our observations. It is this malformation, then, that the clinician will be justified in diagnosing, and in so doing the chances of error which he will run will be relatively few. This malformation constitutes a true pathologic-anatomic type represented by the following tetralogy: (1) stenosis of the pulmonary artery [he might have added "or of the pulmonary valve or infundibulum"], (2) interventricular septal defect, (3) deviation of the origin of the aorta to the right and (4) hypertrophy of the right ventricle, almost always concentric in type. At times there is an additional entirely accessory defect; namely, patency of the foramen ovale. One cannot at the present