The veins had their origin in the liver; the superior vena cava communicated with the right heart, and, as Galen taught, some blood was distributed to the lungs; but the two systems were closed, though Galen believed there was a communication at the periphery between the arteries and veins.

Vesalius accepted Galen's view that there is some communication between the venous and arterial systems through pores in the septum of the ventricles, though he had his doubts, and in the second edition of his book (1555) says that inspite of the authority of the Prince of Physicians he cannot see how the smallest quantity of blood could be transmitted through so dense a muscular septum.

Two years before this (1553),( *) his old fellow student, Michael Servetus, had in his "Christianismi Restitutio" annatomical touch with one another! (*) See the Servetus Notes in the Osler Anniversary Volumes, New York, 1919, Vol.

II .-- Ed.
The publication of the "Fabrica" shook the medical world to its foundations.

Galen ruled supreme in the schools: to doubt him in the least particular roused the same kind of feeling as did doubts on the verbal inspiration of the Scriptures fifty years ago! His old teachers in Paris were up in arms: Sylvius, nostrae aetatis medicorum decus, as Vesalius calls him, wrote furious letters, and later spoke of him as a madman (vaesanus).