The obscurity, and want of precision, with which Hippocrates speaks on this subject, proves how little he was acquainted with it. If we may judge, however, from his attempt to explain the phenomena which the muscles produce, lie must have supposed the cause of these phenomena worthy of serious investigation; and it appears not a little surprising, that he, but particularly Aristotle, who attached such importance to the explana don of animal motion, as to w i lie two books on the sub ject, should yet have been ignorant of the immediate or gans w Lich nature employs in effecting it. Hippocrates had ascribed animal action to the ligaments and ten dons, which, as we have already seen, he termed VElleGt. Aristotle likew ise ascribes it to the hut differed front Hippocrates in selecting those particular which we call arteries, in order to explain its pheno mena. At that time arteries, as their name, indeed, implies, were supposed to contain nothing but air. The great artery of the system was known to rise front the left ventricle of the heart; in which Hippocrates, in conformity with the Pythagorean philosophy respecting heat, had placed the anima, or native lire. Under the influence of such high authority, it was natural for Aris totle to trace all motions to this principle ; and, as it had no isible roninmunication with the other parts of the system but by the ramifications of the great artery, to which he restricted the meaning of the word aocrx, indefinitely applied by Hippocrates to air vessels in ge neral, he was necessarily led to conclude, that this GCVeTX must be the instrument which the soul employs in send ing its spirits to the different joints, and performing its motions by some kinds of repulsion and attraction. This function or the arteries, of course, superseded the use of the brain, the spinal marrow, and the nerves; and sufficiently accounts for those singular opinions which Aristotle entertained concerning the cerebrum and the heart. His theory, fortunately for anatomy, was soon relinquished for one more rational and conformable to truth.
Lycus of Macedon, a very early writer, turned his at tention to this subject, and wrote a voluminous treatise on myology, in which he assigns four muscles to the eye. Although this author was little known during his lifetime, his works, if we may believe Galen, had an ex tensive circulation after his death.
. For nearly three centuries after the time of Lycus, no great improvements were made in anatomy or physiology. Marinus, who flourished under the reign of Nero, in or der to supply the deficiencies of Lycus, resumed the subject of myology, carried it to a higher degree of per fection, and was the first anatomist who suggested the real use of those bodies which are known by the name or glands.
About the beginning of the 2d century, Rufus Ephe sius, from observation, or experiment, was led to con clude, that, besides air, the arteries, in their natural state, contain also a quantity of blood. Erasistratus, too, had found blood in these vessels; but, rather than renounce the established hypothesis, he endeavoured to account for the appearance, by supposing, without being aware of the truth of the supposition, that the veins and arte ries communicate at their extremities; and that, when the arteries are emptied of their air, the blood rushes in from the veins to prevent a vacuum; but that this influx of blood was always followed by morbid effects upon the system. In a work of Rufus Ephesius, called
Onamasia, he explains the different terms employed by preceding anatomists; in some cases he mentions the particular circumstance that gave rise to the name; and he informs us, that, although Herophilus and Erasistra tus had ascertained the function of the nerves, they still allowed the word YEVX, by which they were expressed, to retain its former various meanings, contenting them selves with characterizing the species which they meant !,y particular epithets. The onomasia of Rufus may be considered as the best view of the state of anatomy oc fore the time of Galen.
The celebrated Galen was horn at Pergamus, in Les ser Asia, in the time of the emperor Adrian, and flourish ed under Trajan, Marcus Antoninus, and sonic of their successors. Ilk genius was not more uncommon than his industry. Early initiated in general literature, and having studied with singular diligence in all the philo sophical schools of his time, he, at length, conceived a passion for physic. To prosecute the study of that sci ence with every advantage, he went to Alexandria, then the most celebrated medical seminary in the world There he had frequent opportunities of examining the human skeleton ; but, as the practice of dissecting the human body was now laid aside, he employed himself in dissecting animals which had the nearest resem blance to man, and in comparing their structure with that of birds, quadrupeds, and fishes. To understand the various functions the more perfectly, he used some times to open animals alive. With all the advantages of opulence and rank, of a liberal education, extensive reading, and much travelling, he was enabled to collect all the information of his predecessors; and from great industry, and much observation, has given a fuller de scription of the bones, the ligaments, the muscles, the nerves, the blood-vessels, and the viscera, than had ever been given before. So partial is Portal to his ana tomy, that he hesitates not to prefer it to many recent elementary books; and bids his readers only draw the comparison, to be convinced of the justness of a criti cism so disgraceful to these crude, illiterate compilers, and affording so humbling a specimen of the progress of the human mind.
Passing over his more trivial discoveries, let us take a survey of those which are of some importance. He is known to have the honour of first proving that the arteries, in their natural state, contain blood ; of having first mentioned a communication between the arteries and the veins in the substance of the lungs; and a pas sage of the blood, by that communication, from the right to the left ventricle of the heart. He was the first ana tomist who attended to the peculiar construction of the fetal heart, and who clearly demonstrated the larynx, and showed it to be the organ of voice. His Physiolo gy, more generally known by the title De usu Part il011, does the highest honour to his heart and understanding. It was intended as a hymn to the Creator ; and, from the numerous displays there made of divine power, wisdom, and beneficence, he exults in having presented to the Deity an offering more valuable than hecatombs of oxen.