Page:The advancement of science by experimental research - the Harveian oration, delivered at the Royal College of Physicians, June 27th, 1883 (IA b24869958).pdf/18

 circulation of the blood was dreamt of; the blood was said to flow backward and forward, the vessels having different offices; and instead of the blood being propelled by the contraction of the muscular structure of the heart, the expansion of the heart, the diastole, was regarded as the most important movement and it was attributed to an imaginary innate heat. How different from the simple truth brought to light by the immortal Harvey! When direct experiment was made by Galen, truth was elicited, and one link was formed in the chain of facts connected with the circulation; he shewed, that when an artery was ligatured and afterwards opened, blood was poured out, proving the nature of its contents to be blood and not spirit; and, he also ascertained by experiment that bleeding from the arteries emptied the veins. These observations led to results of a very different character from his deductions from reason; one careful observation as to the nature of the ventricular septum would have disproved his hypothesis of perfor-