In 1862, Raynaud1presented a series of cases under the title of "local asphyxia and symmetrical gangrene of the extremities." He summarized the clinical features as follows: In the slight cases the ends of the fingers and toes became cold, cyanosed and livid, and at the same time more or less painful. In grave cases the area affected by cyanosis extends upward for several centimeters above the root of the nails; at the same time the nose and ears may become the seat of analogous phenomena. Finally, if this state is prolonged for a certain time we see gangrenous points appear on the extremities; the gangrene is always dry, and may occupy the superficial layers of the skin from the extent of a pinhead up to the end of a finger, rarely more. VIEWS ON THE MECHANISM OF ARTERIAL SPASM Raynaud's Hypothesis of Vasomotor Neurosis. —In a second communication