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Rh during his lifetime and amassed a considerable fortune. He built himself in 1547 a fine house in Arezzo, and spent much labour in decorating its walls and vaults with paintings. He was elected one of the municipal council or priori of his native town, and finally rose to the supreme office of gonfaloniere. He died at Florence on the 27th of June 1571.

Personally Vasari was a man of upright character, free from vanity, and always ready to appreciate the works of others: in spite of the narrow and meretricious taste of his time, he expresses a warm admiration of the works of such men as Cimabue and Giotto, which is very remarkable. As an art historian of his country he must always occupy the highest rank. His great work was first published in 1550, and afterwards partly rewritten and enlarged in 1568, bearing the title Delle Vite de’ piu eccellenti pittori, scultori, ed architettori. It was dedicated to Cosimo de’ Medici, and was printed at Florence by the Giunti; it is a small quarto illustrated with many good woodcut portraits. This editio princeps of the complete work is usually bound in three volumes, and also contains a very valuable treatise on the technical methods employed in all branches of the arts, entitled Le Tre Arti del disegno, cioè architettura, pittura, e scoltura. His biographies are written in a very pleasant style, interspersed with amusing stories. With a few exceptions Vasari’s judgment is acute and unbiased. And though modern criticism—with all the new materials opened up by research—has done valuable work in upsetting a good many of his traditional accounts and attributions, the result is a tendency very often to underestimate Vasari’s accuracy and to multiply hypotheses of a rather speculative character. The work in any case remains a classic, however it may be supplemented by the more critical research of modern days.

VASCULAR SYSTEM. I. .—The circulatory or blood vascular apparatus consists of the central pump or heart, the arteries leading from it to the tissues, the capillaries, through the walls of which the blood can give and receive substances to and from the tissues of the whole body, and the veins, which return the blood to the heart. As an accessory to the venous system, the lymphatics, which open finally into the great veins, help in returning some of the constituents of the blood. Separate articles are devoted to the, , and , and it only remains here to deal with the capillaries.

The blood capillaries form a close network of thin-walled tubules from to  of an inch in diameter, permeating, with a few exceptions, the whole of the body, and varying somewhat in the closeness of its meshwork in different parts In the smallest capillaries, in which the arteries end and from which the veins begin, the walls are formed only of somewhat oval endothelial cells, each containing an oval nucleus and joined to its adjacent cells by a serrated edge, in the interstices of which is a small amount of inter cellular cement, easily demonstrated by staining the preparation with nitrate of silver. Here and there the cement substance is more plentiful, and these spots when small are known as stigmata, when large as stomata. As the capillaries approach the arteries on the one hand and the veins on the other they blend and become larger, and a delicate connective tissue sheath outside the endothelium appears, so that the transition from the capillaries into the arterioles and Venules is almost imperceptible; indeed, the difference between a large artery or vein and a capillary, apart from size, is practically the amplification and differentiation of its connective tissue sheath.

Galen, following Erasistratus (ob. 280 ) and Aristotle, clearly distinguished arteries from veins, and was the first to overthrow the old theory of Erasistratus that the arteries contained air. According to him, the vein arose from the liver in two great trunks, the vena porta and vena cava. The first was formed by the union of all the abdominal veins, which absorbed the chyle prepared in the stomach and intestines, and carried it to the liver, where it was converted into blood. The vena cava arose in the liver, divided into two branches, one ascending through the diaphragm to the heart, furnishing the proper veins of this organ; there it received the vena azygos, and entered the right ventricle, along With a large trunk from the lungs, evidently the pulmonary artery. The vena azygos was the superior vena cava, the great vein which carries the venous blood from' the head and upper extremities into the right auricle. The descending branch of the great trunk supposed to originate in the liver was the inferior vena cava, below the junction of the hepatic vein. The arteries arose from the left side of the heart by two trunks, one having thin walls (the pulmonary veins), the other having thick walls (the aorta). The first was supposed to carry blood to the lungs, and the second to carry blood to the body. The heart consisted of two ventricles, communicating by pores in the septum; the lungs were parenchymatous organs communicating with the heart by the pulmonary veins. The blood-making organ, the liver, separates from the blood subtle vapours, the natural spirits, which, carried to the heart, mix with the air introduced by respiration, and thus form the vital spirits; these, in turn carried to the brain, are elaborated into animal spirits, which are distributed to all parts of the body by the nerves. Such were the views of Galen, taught until early in the 16th century.

Jacobus Berengarius of Carpi (ob. 1530) investigated the structure of the valves of the heart. Andreas Vesale or Vesalius (1514–1564) contributed largely to anatomical knowledge, especially to the anatomy of the circulatory organs. He determined the position of the heart in the chest;