thoughtful a man as Vesalius does not appear to have noticed this fact. Andreas Caesalpinus (1519-1603), on the other hand, did observe and correctly interpret the phenomenon; and he made the further observation that physicians were habitually applying the ligature above the spot which they expected to bleed, regardless of the fact that in so doing they were not acting in harmony with their belief concerning the circulation of blood in the veins. Caesalpinus also states, in one part of his writings, that "the blood, carried to the heart by the veins, receives in that organ its last transformation toward perfection, and is then—in this perfected state—transported by the arteries to the remotest parts of the body." So far as it relates to the general movement of the blood this statement is correct, but it errs, as will be shown presently, in mentioning the heart as the locality where the perfecting process takes place. In his final remarks regarding the anatomical relations which exist in the two chambers of the heart Caesalpinus makes the following statement:—
Each ventricle possesses two vessels—one through which the
blood reaches that chamber, and a second one which serves to carry
it out of the ventricle. The vessel through which the blood enters
the right ventricle is called the vena cava, and that by which it
leaves this same chamber is called the pulmonary artery. The
vessel through which the blood arrives in the left ventricle is called
the pulmonary vein, and that through which it leaves this left
chamber of the heart is known as the aorta.
The Circulation of the Blood as Elucidated by Michael
Servetus.—Michael Servetus, a native of Villanueva, Spain,
who in 1553 was burned alive at the stake near the city of
Geneva, Switzerland, because of his heretical teachings, is
not infrequently mentioned as the individual to whom credit
is due for having furnished the first description of the
lesser or pulmonary circulation. There is no question
whatever regarding the justice of according to him at
least a part of this honor, but one should be careful to
specify that Servetus is entitled only to the credit of having
been the first to teach that the blood, in its journey from
