It is manifest from the foregoing papers of this series that brain scar produces brain deformity. This deformity can now be demonstrated clinically by aerograms. It is important to consider whether such deformity must necessarily occasion abnormal function. At first sight this conclusion would be proper and right. Caution, however, must be observed, for many perversions of structure in other forms of disease such as neoplasm occur without sign or symptom. Further, complete symmetry of the ventricles cannot be postulated as constant before injury; one of my patients had an asymmetric system caused by old caisson disease. Congenital malposition and any of the exanthems with cerebral complications or vascular accident may give rise to scar formation and cavity changes. Furthermore, a variety of technic in taking ventriculograms certainly produces a variety of pictures. An abnormal ventriculogram can be produced from a normal person if the head is ever so slightly