The first anatomical treatise containing an account of the lesser, or pulmonary circulation, was the monumental work, _De Re Anatomica, libri xv._, written by Realdus Columbus and sumptuously published at Venice in the year 1559. This, however, was not the first printed account of the lesser circulation. Six years prior to the publication of the book of Columbus, the unfortunate Servetus, in a theological treatise, described correctly the course of the blood in its transit through the lungs. Tried for heresy, Servetus was burned, together with all obtainable copies of his book. Although it had been printed, the work was suppressed; hence it follows that Columbus was the first to publish the great discovery. Of the life of this anatomist we know but little. Born at Cremona, a small Milanese village, the year of his birth is unknown. He died in 1559, while his book was being printed. A few copies were finished before his demise, since a copy belonging to the late Dr. George Jackson Fisher, of Sing Sing, N.Y., contains the author’s own dedication to Pope Paul IV., while in other exemplars, the dedication has been written by the two sons of Columbus, and is addressed to “_Pio IIII., Pont. Max_”. This prelate, on the death of Paul IV., on August 18, 1559, became the head of the Church. Some writers have held that the discovery of the lesser circulation was not made by Columbus independently of Servetus, but that a copy of the book of Servetus had drifted into Italy and had been read by Columbus. There is no direct evidence to support this view. When Vesalius was called to Madrid as physician to Charles the Fifth, Columbus, in 1544, succeeded him in the University of Padua; two years later he filled the anatomical chair at Pisa, and in 1546, Pope Paul IV. called him to Rome. Here he spent the later years of his life, engaged in teaching anatomy and in writing his book. For forty years Columbus pursued his anatomical studies, and in that period he dissected an unusually large number of bodies. Fourteen subjects passed under his scalpel in a single year. [Illustration: TITLE-PAGE OF COLUMBUS’S ANATOMY (Reduced one-half)]