Erasistratus' study of human anatomy is the earliest known. Some 1800 years later Leonardo Da Vinci and Andreas Vesalius performed dissections on cadavers and produced drawings of their observations. Da Vinci showed pores in the septum between the right and left ventricle, probably because the Galenical view was that this is how blood got from one ventricle to the other. To have done otherwise would have been considered heresy.
William Harvey, in his great treatise on the circulation in 1628, proved by the scientific method that the blood made a complete circuit through the body, that venous return equalled arterial outflow. This he was able to do, although microscopes were not yet available to visualize the intervening capillaries.
Capillaries were discovered some years later by Marcello Malphighi.
Return to Index