Page:The Harveian Oration,1902.djvu/25

17 towards the apex. It is generally stated in text-books of physiology that the vagus is the sensory nerve of the heart. This, however, though apparently the case in frogs, in which the vagus and sympathetic nerves run throughout in the same sheath, is not the whole truth as regards man or even animals in general. For after section of both vagi in a cat, Goltz found that pinching, or otherwise irritating, the heart caused reflex movements of the whole body. Though, as has been already remarked, the afferent fibres of the visceral system have not been experimentally determined with the same precision as the efferent, there are many reasons for believing that they are connected with the same spinal segments. This is borne out by Head's brilliant work on the relations between visceral disease and cutaneous pain. Pursuing Ross's hypothesis that the viscera receive their sensory fibres from the same segments of the spinal cord as those from which the somatic sensory roots