MEDICINE 351 rather than a physician, in accounting for the vital operations, had introduced what he termed the archceus, now a chemical ferment and now an intelligent being, as a controlling power; but his opinions found no followers, and only influenced indirectly the progress of medicine. Georg Ernest Stahl, a great chemist as well as physician, appointed professor of medicine in the university of Halle in 1694, was the author of the new system. According to Stahl, the anima (soul) is the great motor and directing principle of the human body. It exercises a recuperative and superintending influence, and guards against injuries, or when they occur takes the best means of repairing them ; it is the common source of all motion, of all secre- tion, of all the vital actions. In showing the insufficiency of the known chemical or phys- ical forces to account for the vital actions, Stahl is happy and ingenious ; but in his sub- tle disquisitions on his own agent, he becomes confused and unintelligible. He has the merit of showing much more clearly than had hith- erto been done the influence which the mind exerts over the body. Stahl's opinions, con- trary to most theories, exerted a controlling influence over his medical practice, reducing the office of the physician to that of watching and forwarding the operations that nature un- dertakes for her own relief; while his doc- trines, set forth with great logical subtlety, at a time when metaphysical speculations were in vogue, though they found few direct follow- ers, yet had a large influence on the minds of the profession. Friedrich Hoffmann, a fellow professor with Stahl at Halle, was a volumi- nous writer, whose reputation has extended to our own time. He attributed to the nervous system most of the functions and influences which Stahl ascribed to the anima. In speak- ing of the animal fibre, he ascribes to it a cer- tain natural "tone," which maybe increased into " spasm" or diminished to "atony;" and connected with both these hypotheses, while admitting the fluids to be sometimes primarily diseased, in the majority of cases he thought the solids were first affected. As early as 1752 Boissier de Sauvages of Montpellier published his methodic nosology, in which he endeavors to class and distinguish diseases in the same manner as the vegetable kingdom is classed and described by the botanists. His work was of great use in the advancement of medicine, and remained the standard treatise on the sub- ject until the publication in 1772 of the nosol- ogy of Cullen. This author, a professor first in the university of Glasgow and afterward in that of Edinburgh, contributed greatly to raise the latter school to the high rank which it has since enjoyed. His teachings and writings exercised a wide influence, and their effects can still be traced in English medicine in our own day ; his descriptions of disease in particular are remark- able for their force and conciseness, but the progress of science has shown the fallacy of the views on which his system was founded. A 544 VOL. xi. 23 contemporary and rival of Cullen, John Brown, a man of genius but of wayward and ill regula- ted character, was likewise the author of a sys- tem which enjoyed a temporary popularity, and which, somewhat modified, found eminent followers in Italy within a recent period. The end of the last century witnessed the most im- portant practical discovery ever made in medi- cine. Up to that period smallpox annually committed the most fearful ravages ; the deaths from it in Europe alone were estimated to amount to 400,000 a year, while it left many blind or disfigured. The practice of inocula- tion, brought from Constantinople by Lady Mary Wortley Montagu, had indeed diminished the evil, but the remedy itself was attended with great inconvenience, and was not desti- tute of danger. The discovery of Jenner, an- nounced in his " Inquiry into the Causes and Effects of the Variola) Vaccine " (London, 1798), has placed the disease completely under our control ; and if it still commits occasional ravages, it is owing to the laxity of the laws and the carelessness of individuals. Another great improvement in practical medicine, the use of lemon juice, sour krout, &c., in the dietary of seamen, by which scurvy, which formerly committed fearful havoc on both the naval and mercantile marine, has become almost unknown, is due to the naval surgeons of the last century. In the present century practical medicine has made greater advances than in any other similar period. This may be attributed : 1, to the brilliant discoveries which have ren- dered chemistry a new science, by the aid of which we are now able to comprehend much more clearly than before the processes of nutri- tion, respiration, calorification, secretion, and excretion; 2, to the increased attention paid to microscopy, by which the mode of devel- opment of the germ, the organization and growth of the different tissues, the process of repair and that of inflammation, and other morbid processes, have been investigated; 3, to the rapid progress of experimental physi- ology, aided by chemistry and microscopy ; 4, to the increased cultivation of comparative anatomy and physiology ; 5, to the cultivation of morbid anatomy not only in relation to the symptoms of disease during life, but to the various degrees of morbid developments, and to the relation which those developments bear to each other ; 6, to the new and more perfect methods of investigating disease, by which its diagnosis has become more certain. Under the last head two discoveries are prominent, which have changed the whole face of medi- cine, giving it a degree of certainty which at one time seemed hopeless : that by Laennec of auscultation and percussion, and that by Bright of the disease of the kidney which bears his name. The development and perfecting of each of these discoveries has employed and is employing the lives and founding the reputa- tion of a vast number of learned, zealous, and able men. 7. The discovery by pharmaceuti-
