. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 296 NATURAL HISTORY OF ORGANIZED BODIES. pie way some of tlic principal plientying itself into elastic vessels than it would meet with if the arterial system were formed of rigid conduits. Now this effect of the arterial elasticity has been contested by the whole body of physiologists. Some of them have held, with Bichat, that the circulation would be effected quite as well in inert tulies as in elastic ones, the only difference being that


. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 296 NATURAL HISTORY OF ORGANIZED BODIES. pie way some of tlic principal plientying itself into elastic vessels than it would meet with if the arterial system were formed of rigid conduits. Now this effect of the arterial elasticity has been contested by the whole body of physiologists. Some of them have held, with Bichat, that the circulation would be effected quite as well in inert tulies as in elastic ones, the only difference being that in inert vessels no pul- sation would be felt, (jthers, relying on experiment, asserted that two tubes, one elastic, the other inert, give passage to the same quantity of liquid if both have the same calibre; and this is pcrfecth' true if the flow of the liquid takes jDlace under a constant discharge, but ceases to be true if the afflux of the licjuid occurs in an intermittent manner, as is the case with the circidation of the blood. Still other physiologists, struck witll the regularity of the course of the blood in the small vessels, have considered the elasticity of the arteries as an additional force, which propels the blood in the arteries during the repose of the heart. But these also were in error, and we might refute their opinion by saying, with Berard, that the elastic force of the arteries is in reality only indirectly contrib- utory, a force cVemprunt, and that the heart is the sole impulsive agent which exerts an active part in the circulation. Nevertheless, I maintain my proposi- tion : the elasticity of the arteries is favorable to the course of the blood, but it does not act as an impulsive force. It diminishes the resistance ivhich tlie heart experiences when it propels the blood in tlie vessels. The annexed schematic apparatus will enal)le me to demonstrate this A ]\[ariotte vase V is raised on a support. From this vase proceeds a large tube furn


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