Action of Valves
Diagram to illustrate the mode of action of the valves of the veins. Labels: C, the capillary end, and H, the heart end of the vessel.
Martin, H. Newell & Martin, Ernest G. The Human Body: An Account of Its Structure and Activities and the Conditions of its Healthy Working (New York: Henry Holt and Company, 1917) 338
Courtesy the private collection of Roy Winkelman