Andrea Argoli (1570-1657), professor of mathematics at the University of Padua from 1632 to 1657, published at Padua in 1644 in the work Pandosion sphaericum an accurate and succinct exposition of the theory of the circulation of the blood. Argoli's exposition actually is a summary of Jan de Wale's (Walaeus, 1604-1649) first Epistola de motu sanguinis, republished at Padua, just a year prior to the Pandosion, as an appendix to the fourth edition of De motu cordis of William Harvey. Argoli cites a hitherto unknown very expert anatomist at Padua, John George Verden, who carried out experiments at Padua designed to measure the volume of arterial blood emitted from each contraction of the left ventricle in small and large dogs. It is now possible to identify Verden with Johann Georg Wirsung (1589-1643), from Augsburg, the discoverer of the main pancreatic duct by ligation of the chyliferous ducts.