WHEN THE FUNCTIONS of the brain are disordered in neuromuscular, structural, chemical, electrical, or other observable ways, the tendency has been to look for the organic causes of the disorder or malformation. Function is the other face of structure. Functions are dependent upon organic structures, hence, the obvious, though not necessarily accurate conclusion is customarily drawn that disordered function must be caused by disordered structures, and frequently we tend t o look no further. We tend, in our thinking, to be limited to the idea that physical factors such as genetic, viral, bacterial, parasitic, chemical, iatrogenic, complications of pregnancy, prematurity, postmaturity, and the like are the kind of factors that must be involved in the brain damage that causes the observable malfunction. This is often quite true, but it is also quite frequently not the whole story. N o more the whole story than that pellagra is due to a deficiency o f vitamins of the B complex, especially niacin (nicotinic acid) and its amide. It is quite true that under any conditions a diet deficient in nicotinic acid and other vitamins ol' the B complex will