Page:The Harveian Oration,1902.djvu/23

 ated apart, we made a very strict ligature, which being done the dog was presently silent and seemed stunned, with a great trembling of the heart."

Willis imagined that the sympathetic fibres of the cardiac plexus were able by a kind of anastomosis to supply the animal spirits after the vagi were divided. The totally different function of the sympathetic was first demonstrated in 1866 by von Bezold, who found that stimulation of the filaments proceeding from the ganglion stellatum—derived, as it has been proved by subsequent researches, from the upper thoracic anterior roots—caused effects entirely antagonistic to those of the vagus, viz., acceleration of the rhythm and increased force of the cardiac contractions. The visceral system also contains sensory or afferent fibres, which are the medium of communication between the viscera and the sensorium, but the mode of origin, course and termination of these nerves are less accurately known than those of the efferent class. The heart, like the viscera, is in normal conditions but poorly endowed