HISTORY.] ANATOMY 801 The first three books of the History of Animals, a treatise consisting of ten books, and the four books on the Parts of Animals, constitute the great monument of the Aristotelian Anatomy. From these we find that Aristotle was the first who corrected the erroneous statements of Polybus, Syennesis, and Diogenes regarding the blood vessels, which they made, as we have seen, to arise from the head and brain. These he represents to be two in number, placed before the spinal column, the larger on the right, the smaller on the left, which, he also remarks, is by some called aorta (aopr-tj), the first time we observe that this epithet occurs in the history. Both he repre sents to arise from the heart, the larger from the largest upper cavity, the smaller or aorta from the middle cavity, but in a different manner and forming a narrower canal. He also distinguishes the thick, firm, and more tendinous structure of the aorta from the thin and membranous structure of vein. In describing the distribution of the latter, however, he confounds the vena cava and pulmonary artery, and, as might be expected, he confounds the ramifications of the former with those of the arterial tubes in general. While he represents the lung to be liberally supplied with blood, he describes the brain as an organ almost destitute of this fluid. His account of the distribu tion of the aorta is wonderfully correct. Though he does not notice the coeliac, and remarks that the aorta sends no direct branches to the liver and spleen, he had observed the mesenteric, the renal, and the common iliac arteries. It is nevertheless singular that though he remarks parti cularly that the renal branches of the aorta go to the substance and not the pelvis (/coiAt a) of the kidney, he appears to mistake the ureters for branches of the aorta. Of the nerves (vevpa) he appears to have the most confused notions. Making them arise from the heart, which he says has nerves (tendons) in its largest cavity, he represents the aorta to be a nervous or tendinous vein (vevpwS^s Ae/3s). By and by, afterwards saying that all the articu lated bones are connected by nerves, he makes them the same as ligaments. He distinguishes the windpipe or air-holder (apr^pia.) from the oesophagus, because it is placed before the latter, because food or drink passing into it causes distressing cough and suffocation, and because there is no passage from the lung to the stomach. He knew the situation and use of the epiglottis, seems to have had some indistinct notions of the larynx, represents the windpipe to be neces sary to convey air to and from the lungs, and appears to have a tolerable understanding of the structure of the lungs. He repeatedly represents the heart, the shape and site of w r hich he describes accurately, to be the origin of the blood-vessels, in opposition to those who made them descend from the head ; yet, though he represents it as full of blood and the source and fountain of that fluid, and even speaks of the blood flowing from the heart to the veins, and thence to every part of the body, he says nothing of the circular motion of the blood. The diaphragm he distinguishes by the name Stao)//.a, and v7row/.<.a. With the liver and spleen, and the whole alimentary canal, he seems well acquainted. The several parts of the quadruple stomach of the ruminating animals are distinguished and named ; and he even traces the relations between the teeth and the several forms of stomach, and the length or brevity, the simplicity or complication, of the intestinal tube. Upon the same principle he distinguishes the jejunum (fj vfja-TLs), or the empty portion of the small intestines in animals (TO Zvrepov ACTTTO V), the c&cum (rv(Aov TL KCU oy/ccoSes), the colon (TO KwAov), and the sigmoid flexure ( orevcorepov KOI flXiyi^rov}. The modern epithet of rectum is the literal translation of his description of the straight progress (d>6v) of the bowel to the anua (TTOWKTO S). He knew the nasal cavities and the passage from the tympanal cavity of the- ear to the palate, afterwards described by Eustachius. He distinguishes as " partes similares " those structures, such as bone, cartilage, vessels, sinews, blood, lymph, fat, flesh, which, not confined to one locality, but distributed throughout the body generally, we now term the tissues or textures, whilst he applies the term " partes dissiniilares" to the regions of the head, neck, trunk, and extremities. Next to Aristotle occur the names of Diocles of Carystus, and Praxagoras of Cos, the last of the family of the Asclepiadoe. The latter is remarkable for being the first who distinguished the arteries from the veins, and the author of the opinion that the former were air-vessels. Hitherto anatomical inquiry was confined to the examina tion of the bodies of brute animals. We have, indeed, no testimony of the human body being submitted to examina tion previous to the time of Erasistratus and Herophilus ; and it is vain to look for authentic facts on this point before the foundation of the Ptolemaic dynasty of sovereigns in Egypt. This event, which, as is generally known, succeeded the death of Alexander, 320 years before the Christian era, collected into one spot the scattered embers of literature and science, which were beginning to languish in Greece under a weak and distracted government and an unsettled state of society. The children of her divided states, whom domestic discord and the uncertainties of war rendered unhappy at home, wandered into Egypt, and found, under the fostering hand of the Alexandrian monarchs, the means of cultivating the sciences, and repaying with interest to the country of Thoth and Osiris the benefits which had been conferred on tlie infancy of Greece by Thalcs and Pythagoras. Alexandria became in this manner the repository of all the learning and know ledge of the civilised world ; and while other nations were sinking under the effects of internal animosities and mutual dissensions, or ravaging the earth with the evils of war, the Egyptian Greeks kept alive the sacred flame of science, and preserved mankind from relapsing into their original barbarism. These happy effects are to be ascribed in an eminent degree to the enlightened government and liberal opinions of Ptolemy Soter, and his immediate successors Philadelphus and Euergetes. The two latter princes, whose authority was equalled only by the zeal with which they patronised science and its professors, were the first who enabled physicians to dissect the human body, and prevented the prejudices of ignorance and superstition from compromising the welfare of the human race. To this happy circumstance Herophilus and Erasistratus are indebted for the distinction of being known to posterity as the first anatomists who dissected and described the parts of the human body. Both these physicians flourished under Ptolemy Soter, and probably Ptolemy Philadelphus, and were indeed the principal supports of what has been named in medical history the Alexandrian School, to which their reputation seems to have attracted numerous pupils. But though the concurrent testimony of antiquity assigns to these physicians the merit of dissecting the human body, time, which wages endless war with the vanity and ambition of man, has dealt hardly with the monuments of their labours. As the works of neither have been preserved, great uncertainty prevails as to the respective merits of these ancient anatomists ; and all that is now known of their anatomical researches is obtained from the occasional notices of Galen, Oribasius, and some other writers. From these it appears that Erasistratus recognised the valves of the heart, and distinguished them by the names of tricuspid and sigmoid ; that he studied particularly the shape and structure of the brain, and its divisions, and cavities, and membranes, and likened the convolutions to the folds of the iejunuin ; that he first formed a distinct idea cf tlio I. 10 r 354. 341. Alexan drian school. 85. Erasis tratus.
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