He demonstrated, for example, that the fluid which enters the left ventricle from the lungs is genuine blood, and he also learned by the same method of investigation the true nature of the systole and diastole of the heart and the relations of these acts to the pulse and to the changes in the position of the heart. The discovery of all these facts constituted a material advance in our knowledge of the physiology of that organ; but, from this time onward, for a period of nearly three-quarters of a century, no further advance was made until William Harvey of England appeared on the scene. The explanation of the failure of such able investigators as Realdus Columbus, Vesalius, Servetus and others to push their researches still further is to be found largely in the fact that they were all still in bondage to the doctrines taught by Galen centuries earlier, and probably more particularly to that dogma which maintains that blood—if it is to be accepted as genuine or fully formed blood—must first have been elaborated in the depths of the liver. The impossibility of harmonizing such a dogma with the facts which by that time were well established, is too plainly evident to warrant further discussion in these pages.
Discovery of Valves in the Larger Veins by Fabricius ab Acquapendente.—The discovery of the presence of valves in the interior of the larger veins is credited by some to Cannani (1546) and by others to Fabricius ab Acquapendente (1574), but the best authorities appear to favor the claim of Fabricius to this honor. There are also a few authorities who maintain that Fra Sarpi, the celebrated monk and scientist of Venice, is entitled to be considered the discoverer of the valves in veins, but Tiraboschi, the historian of Italian literature, makes it clear that this claim is unfounded.
Although it was known to Fabricius that these valves are inclined toward the heart, he does not appear to have appreciated the fact that this arrangement is entirely incompatible with Galen's doctrine that the flow of venous blood is from the liver toward the extremities; nor did any other anatomist, so far as I am able to learn, discover this
