Contineatur, De. Præsagatione ex Pulsibus, De Simplicum Medicamentorum Temperamentis et Facultatibus, De Compositione Medicamentorum, De Curandi Ratione per Venæ Sectionem, De Sanitate Tuenda, Quod Animi Mores Corporis Temperamenta Sequantur, De Foetuum Formatione, and a few others.

In the

of the st of the works cited above, we are told

of the few occasions enjoyed by the ancients for acquiring correct anatomical knowledge. The first five books of this treatise are occupied in describing the muscles, many of which are here mentioned for the first time. In connection with the muscular system he speaks of the blood-vessels. In the sixth book are described the organs of digestion; in the seventh, the heart; in the eighth, the respiratory organs; in the ninth, the brain and spinal marrow ; and in the six remaining books, which have perished, he treated of the eye, the tongue, the pharynx, the larynx, the os hyoides, the history of the arteries and veins, the cerebral and spinal nerves, and the organs of generation. Many facts incorporated in this important production have been claimed to be the discoveries of later times.

The treatise De Usu Partium, written soon after his return to Rome, is also replete with anatomical details, interspersed with physiological opinions; but is rather a dissertation on final causes than a strictly anatomical performance: the author's main object being to disprove the doctrines of Epicurus and demonstrate the existence of a superintending Providence, from the wonderful adaptation of

means to ends in the organization of the human frame. In this admirable discourse is found that eloquent exposition of the powers and uses of the human hand, the leading thought of which may have been borrowed from Anacreon, but upon which no subsequent writer has been able to improve. And here, too, are found those hymns to the Deity, and other pious ejaculations, so worthy of the philosopher and moralist. This work is in seventeen books, and has been preserved entire..

The treatise De Locis Affectis in six books, was the work of his maturer years. In this, with wonderful sagacity he points out every part of the body subject to pains, convulsions, paralysis, or other symptoms; and to which our attention should be directed for investigating into the causes of disease. This valuable treatise, which is occupied mainly with pathology and symptomatology, the learned Haller held in higher estimation than any other of Galen's works.

The Ars Medica was for many centuries the textbook upon which the students of Salernum, and other schools of the middle ages, were examined. before receiving permission to practice. Commencing with the definition of medicine, it treats of the signs of health, of the temperaments generally, and of their influence on special organs in health and disease. It next treats of the signs of disease-general and local, of prognostic indications, of the causes of disease, of the means of preserving health and of restoring it when disordered; thus furnish

ing in small compass an exposition of the whole of Galen's system of medicine.

The Methodus Medendi, in fourteen books, was the work of his old age, and was held by his followers in nearly the same estimation as the Ars Medica. The two books, on the same subject, addressed to Glauco, treat mostly of generalities. More information, it has been said, may be obtained from this work than from the whole medical literature of the Arabians. Galen, as before remarked, frequently refers incidentally to his own history, particularly in the Administrationes Anatomicæ, Ars Medica, De Usu Partium, De Locis Affectis, De Præcognitione. ad Epigenem, De Antidotis, De Theriaca ad Pisonem, and in a work of his later years entitled De Propriorum Animi cujusque Adfectuum Dignotione et Curatione.

His original investigations were chiefly in the department of anatomy. In this he made many discoveries, mostly in the muscular system. But from the manner of treating the subject, it is difficult to determine precisely how much of his anatomical knowledge was derived from his own researches, and how much from the labors of his predecessors. He was the first to describe the popliteal muscle, the platysma myoides, the sterno and thyro hyoidei, and probably many others. In angiology he was not much in advance of the early Alexandrians. Like them, he placed the origin of the veins in the liver, of the arteries in the heart. He was familiar with the anastomoses of the two

orders of vessels; he traces the current of blood from the liver, the supposed fountain of the venous portion, into the right ventricle of the heart, and through the pulmonary vessels to the left ventricle. He was acquainted with the uses of the opening between the right and left auricle; but in other respects his ideas of the course and distribution of the blood were confused and incorrect. He appears to have made several discoveries in the nervous system, he points out the tubercula quadrigemina, corpus callosum, and septum lucidum; he derives the nerves of sensation from the brain, those of motion from the spinal marrow, and to some nerves he assigns both sentient and motive power; he denies the decussation of the optic nerves, but admits their junction at the commissure. He describes the par vagum and its connections with the sympathetic. Certain organs, as the heart and bloodvessels, he supposes to be destitute of nerves, and hence devoid of sensibility. He took much trouble to determine the structure and development of the human foetus. He allows no occasion to escape for impressing upon his students the importance of anatomical knowledge, advising them to inspect the human cadaver when possible; or where this cannot be obtained, to dissect monkeys and other animals. These were the subjects of his own study; and from them nearly all his own anatomical descriptions were derived.

In respect to physiology, he speaks of the living body as a unit, though constituted of parts or organs, simple and compound, of humors, and of

spirits. With Empedocles he maintained, that all the parts, by which he means the material struc tures, whether simple or compound, are constituted of the four primitive elements, fire, air, earth, and water; from which are derived the four corresponding qualities, the hot, the cold, the dry, and the humid.

He also enumerates four humors; the blood, which is red, hot, and moist; the phlegm, which is white, cold, and humid; the bile, which is yellow, hot, and dry; and the melancholia, or atrabile, which is black, cold, and dry. These two latter he holds to be partly excrementitious. From the combination of the elements and their respective qualities, results the complexion or Chrasis, of each part or texture of the body. The preponderance of one or another of the four humors gives rise to the corresponding temperaments. In common with the Peripatetics, he attributed the essential phenomena of life to certain occult forces inherent in the several parts or organs. These forces he divides into the vital, the animal, and the natural. The seat of the first is in the heart; of the second, in the brain; and of the third in the liver. But above all these forces he admits, with Hippocrates, the presiding and ruling influence of Nature; a word which by ancient usage was equivalent to the modern expression, vitality, vital force, organie force, or principle of life.

The spirits, under the common name of Pneuma, he also divided into the vital, the animal, and the natural; corresponding with the respective forces