But neither unrelated theories nor unreasoning empiricism was destined to satisfy the nineteenth century. Bichat, on the very threshold of that century, published his epoch-making work on general anatomy, in which he pointed out that, since the organs have tissues and membranes in common, the seat of disease was this common tissue rather than the organs considered individually. This work of Bichat vastly simplified physiology and anatomy, both normal and pathological, and coloured the work in the latter field done by the followers of Morgagni. Broussais's works (published in ISoS and ISI6), which were based upon the sthenic and asthenic theory of Brown, stimulated research in similar fields ; and the investigations of local ailments was greatly aided by the introduction of percussion and auscultation by Auenbrugger of Vienna and Laennec of Paris, the latter of whom is known to fame as the inventor of the stethoscope and as the founder of modern clinical science. One of the familiar names of the early nineteenth century is that of Richard Bright, the investigator of kidney-diseases ; and a number of observers in France, Scotland, and England did valuable work in the study and discrimination of the continued fevers.
In America, also, the nineteenth century was signalised by a phenomenal development of medicine. At the beginning of the century there were only three medical schools in the United States, and but two general hospitals. Medical students who could not afford to go abroad to Paris, London, or Edinburgh studied privately with some physician near their homes. The rapid growth in population demanded an increase in facilities for medical service greater than legitimate channels could supply, and, although medical schools sprang up with amazing rapidity, many of them turned out a product scarcely better than the frankly uneducated. But, though the ignorant might be satisfied with such service, the large number of intelligent people in the country would not put up with it, and all the schools of the better sort, with Harvard in the lead. set up higher standards, which the increasing development of medical knowledge has never suffered to lapse, but has compelled rather a more and more exhaustive training.
The latter half of the century has seen the development of the research laboratory, the triumphs of bacteriology, and the dawn of the era of pre ventive medicine. Even to the laity these triumphs are more or less familiar. The names of Pasteur, Koch, and Lister are household words ; and some knowledge of the part played in human lives by bacteria, pathogenic and non-pathogenic. is reaching the general population and making possible the
great campaigns being organised against the more threatening of infectious diseases. The germs of many of these diseases have been successfully isolated ; and even where this has not vet been achieved, as in the case of smallpox, some knowledge of their action may make intelligent and effective prophylaxis possible.
The discoveries of bacteriology gave rise to the serum-treatment, \which has already accomplished so much and promises so much more. Diph theria, for instance, has had its mortality reduced one-half by this means. The conditions under which the various disease-germs thrive, and those which are necessary for their transmission, have been investigated ; and the removal of such conditions has made it possible to control, not only diphtheria and smallpox, but many other diseases which formerly appeared in epidemics that justly won the epithet of " scourge." Among these are bubonic plague, Asiatic cholera, typhus, typhoid and yellow fever ; and earnest " campaigns of education " may yet make it possible to do as much with regard to tuberculosis and syphilis.
Another change wrought by the modern understanding of the nature of disease is in the therapeutic methods employed by the medical profession. Where the physicians of the early half of the nineteenth century put all their faith in the efficacy of drugs, the modern physician, while not discarding their aid, still realises more intelligently their limitations ; and, while study ing with painstaking care the action of those drugs which have proved of value, he depends more and more on the regulation of the patient's manner of living, on diet, bathing, exercise and massage—in short, on everything that can give the natural powers the best chance in coping with the disease. Even the general public is beginning to appreciate the new point of view, and patients are found who do not refuse to believe that they are getting their money's worth when the doctor gives them nothing to " take " except advice.
A glance at the recent developments in medicine would be quite incomplete did it omit to notice the prominent part played by mental representations in provoking and fostering, and likewise in curing, disease. Physicians of prominence, in Europe and also in America, are giving this subject keen and serious attention ; and the cures wrought by " psychotherapeutics " can no longer be regarded as based on ignorance and superstition. The principles applied indiscriminately and unintelligently by " healers " of various sorts are capable of scientific application as well.