Page:The Harveian oration delivered at the Royal College of Physicians June 26, 1889 (IA b22361285).pdf/12

 I have said that Servetus scarcely did more than offer a conjecture on the pulmonary columbus. In 1659, however, Realdus Columbus made so broad and comprehensive a statement regarding the circulation, that we must allow him to have been so near the truth that a little more independence of thought and experimental constructiveness must have given him the glory which brightens the memory of our illustrious countryman. Be it remembered, however, that it was precisely because he lacked these qualities that he could not be that which Harvey became—the discoverer of the circulation. How strongly to the point are the following words of Columbus: ‘The blood, when once it has entered the right ventricle from the vena cava, can in no way again get back for the tricuspid valves are so placed, that whilst they give a ready passage to the stream inwards, they effectually oppose its return. The blood continuing to advance from the right ventricle into the vena arteriosa or pulmonary artery, once there, cannot flow back upon the ventricle, for it is opposed by the sigmoid valves situate at the root of the vessel. The blood, therefore, agitated and