From observation at the operating table it is exceedingly difficult to describe with anything like scientific accuracy the limitations of a tumor in relation to the three subdivisions of the frontal lobe—the motor area, the premotor area and the frontal, or prefrontal, area. Not only does the tumor overlap the boundaries of these arbitrary subdivisions, but surrounding the tumor there are areas of vascular and proliferative changes that extend varying distances beyond the actual limits of the tumor. Takagi1described diffuse edema, with large perivascular spaces and dilatation of all the veins in the neighborhood, among the pathologic processes that surround the tumor. In 1913 he said: It is important to remember that when tumor develops in the brain and exists for a long time, alteration of the brain tissue even in regions remote from the tumor may occur. Failure to take this alteration into consideration may lead to