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 350 MEDICINE same time Borelli and others showed the mech- anism by which respiration is accomplished. In 1622 Gaspard Asselli, professor of anatomy at Milan, discovered the lacteal vessels; and about 30 years later Jean Pecquet demonstra- ted the reservoir which bears his name, toge- ther with the thoracic duct from its commence- ment to its termination in the left subclavian. The lymphatic system, the nerves, the brain, and the organs of special sense were all stud- ied with care. In 1747 Haller published his Pri- me* Linece Physiologic, and 10 years later his Elementa Physiologic Corporu Humani ; and from this period physiology had a distinct ex- istence as a science. In the mean time the materia medica had been enriched by a num- ber of new articles. The chemists had intro- duced a variety of metallic and alkaline salts, and the new world had yielded guaiacum, sar- saparilla, ipecacuanha, &c. ; but two remedies from their importance require a more special notice. On the first appearance of syphilis the surgeons had attacked it by means of mercu- rial frictions, and with success ; but their em- ployment in numerous instances was attended by such terrible consequences, that they grad- ually fell into disuse. Paracelsus had employed mercury internally, but in the hands of such a practitioner it could rarely be productive of other than mischief ; the Galenists condemned its use, and the chemical physicians gave it rarely and secretly. Gradually it again came into favor, and in 1750 Van Swieten, the phy- sician of Maria Theresa, directed all the cases of syphilis in the military and civil hospitals of the Austrian empire to be treated with small doses of corrosive sublimate in solution, and the practice soon became common through- out Europe. The ancients, with whom mala- rious diseases were common, had no specific means of arresting their attack ; even mild in- termittents often continued for an indefinite time, and finally induced organic changes and dropsy. In 1639 Peruvian bark is said to have been introduced into Spain by the countess of (Jinchon ; and though the extravagance of its price, the adulterations it sometimes met with, and its nauseousness were obstacles to its suc- cess, its use soon became common throughout Europe. As chemistry, from vain search after the philosopher's stone or the elixir vita, began to assume the aspect of a science, it influenced more markedly the prevailing medical doctrines. Francis de le Boe or Sylvius, a Fleming called to the professorship of practical medicine in 1658, was the first to present a chemical theory of the actions of the animal economy. Ac- cording to this theory, digestion and nutrition were the consequence of specific fermenta- tions, in which the saliva, the pancreatic juice, and the bile take part. Fevers were produced by other fermentations caused by a vicious bile >r lymph. Certain of the humors were natu- rally acid, others alkaline ; in a state of health these were in equilibrium, but disease was con- sequent upon the predominance of one or the other. This doctrine, more or less modified, had many followers, and for a time was preva- lent both on the continent and in England. Willis and Thomas Sydenham may be ranked among the iatro-chemists ; but Sydenham is much the more remarkable for the careful and conscientious manner in which, uninfluenced by theory, he gave himself up to the observa- tion of disease. While the chemical school was taking form at the north, in Italy the progress of physical science was turning the attention of theoretic physicians in a new direction. Alfonso Borelli, a profound mathe- matician, was the originator of what has been termed the iatro-mathematical school. In the first part of his work De Motu Animalium he applies the received principles of physics to the subject of muscular action, treats of the various attitudes and modes of progression of men and animals, of walking, running, leap- ing, flying, swimming, and enters into learned and curious calculations of the amount of force which is expended in particular acts. In the second part he treats of the internal move- ments, of those of the heart, of the blood in the vessels, and of the action of the intestinal canal ; the whole body was regarded as a ma- chine, and the laws of mechanics, of hydraulics and hydrostatics, were rigidly applied to it. As an instance of the futile but elaborate calcula- tions into which the mathematical physicians were led, Borelli calculates that the heart at each contraction overcomes a weight of 180,- 000 Ibs. The physiology of the mathematical school had its influence upon their pathology ; and the terms derivation, revulsion, lentor, ob- struction, resolution, &c., all founded on phys- ical principles, were universally used. The mathematical school had many and eminent followers throughout Europe: in Great Brit- ain, Pitcairn, Freind the historian of medicine, and Mead; in Holland and Germany, Boer- haave and John Bernoulli ; in France, Sau- vages, the eminent and learned nosologist, and Senac, the physician of Louis XIV. Hermann Boerhaave, professor of medicine at Ley den, had great talent and immense learning, and was an accurate observer and a sagacious prac- titioner. He was one of the first to devote himself to clinical teaching, and he was fortu- nate in the devotion of such pupils as Van Swieten and Haller. Unfortunately for his permanent reputation, he lived in an age of transition, and his system, generally received during his lifetime, scarcely survived its author. Jean Senac, another of the mathematical phy- sicians, to whom Morgagni applies the epithet of " great," published a book on diseases of the heart, which has only been rendered obsolete by the introduction of the new methods of aus- cultation and percussion. While the chemical and mathematical physicians were reducing the actions of the living body to the laws which govern inert matter, a wholly opposite tenden- cy manifested itself in Germany. Previously indeed Van Helmont, a mystic and alchemist