De Motu Cordis

1628: a thin quarto out of Frankfurt

A Latin first edition of William Harvey's Exercitatio anatomica de motu cordis et sanguinis in animalibus appeared at Frankfurt am Main in 1628, issued by William Fitzer.

It ran to 72 numbered pages, four unnumbered pages and two leaves of plates. The first-edition catalogues consulted establish the year but no particular day or month.

The argument by arithmetic

The book put an experimentally argued model into print: the heart propels blood into the arteries, and the veins return it from the body to the heart. Dissections, ligatures and the one-way action of the cardiac and venous valves established the direction of flow.

Harvey's other lever was quantitative. Reckoning on more than a thousand heartbeats in half an hour — some people, he noted, reaching two to four thousand — he calculated a half-hour output ranging from 10 pounds 5 ounces to 83 pounds 4 ounces, depending on how much was assumed expelled per beat.

That was far more than food could continually replace, so the blood had to be returning in a circuit.

What he could not see, and what he did not win

Harvey did not discover the venous valves; earlier anatomists had described them. His contribution was explaining their role in one-way circulation.

He never saw capillaries, and considered instead direct anastomoses and passage through porous tissue. Microscopic evidence of the capillary connection came from Marcello Malpighi, after Harvey's death.

Nor did publication settle the question: prominent physicians initially rejected or attacked the argument.