The Pedestrian's Record

THE PEDESTRIAN'S RECORD. 115 slightest aperture, and sometimes will even burst its barriers. And so with the heart and the circulatory system : the sharp strokes of the legs whilst engaged in rapid progression cause the heart to pump too hard, and drive with dangerously excessive force the blood through the blood-vessels, which, unlike the rubber tubing, which usually is of the same diameter from end to end, decreases gradually in its circum­ ference as it leaves the heart to its terminal capillary. By this disposition of arterial and venous systems blood driven at an increased speed would impose greater stress upon a conduit decreasing in diameter from its commencement to its finish than in a tube of the same circumference from mouth to exit, as we observe in india-rubber tubing, and yet liquid passing through tubing of the same magnitude, if forced at greatly-increased speed, tries to overleap its barriers, so do the blood-vessels undergo a similar process of straining when the flow of blood is accelerated by rapid locomotion through them, and sometimes, like the broken tubing, they get ruptured. The surgeon cannot suture the rent, neither can he by any means draw the injured parts together, soas to insure their immediate reparation. He can prescribe a system of living and dietary calculated to preserve or build up the strength, so as to give the vis medicatrix naturd a chance to exert her all-powerful influence in the curative process ; but even then the cure is affected by the growth of organisms, such as aneurisms, tumours, and other enlargements, which necessitate I 2