methods of a science of clinical medicine and have aided materially in the advance of this branch of medicine.
Such are the methods and problems of present-day research in medicine. The history of medicine teaches us that new methods and fruitful hypotheses may be brought forth at any time; new diseases, on the other hand, can now be expected only through changes in social relations and practises or as the result of new industries. Advance, therefore, would appear to lie in the concentrated application of present methods to present problems and in the application of such new methods, as may be confidently expected to appear from time to time, in any science which is so actively cultivated as is the science of modern medicine.
In this narrative of research medicine I have grouped the various phases of my presentation about men or events. These, as Hippocrates and Galen in antiquity; Vesalius and his influence on anatomy; Paré and his observations in surgery; Harvey, Hunter and Haller and their more or less isolated discoveries in physiology; Morgagni and his observations in pathological anatomy; and Jenner and his discovery of vaccination, represent the epoch-making efforts of workers widely separated and more or less isolated. In the early part of the nineteenth century, Johannes Müller, Liebig and Rokitansky founded respectively the sciences of physiology, organic chemistry and pathological anatomy upon the basis of concentrated laboratory effort and gave to these sciences an impetus the result of which we recognize to-day in the importance which they have attained. The main line of advance, however, has been in the past 70 years, and was made possible by the study of cells, through (1) the work of Schleiden on vegetable cells and of Schwann on animal cells thus establishing the cell doctrine; (2) the application of this theory by Virchow to pathology, and (3) Pasteur's conception of the role played by microscopic cells in fermentation and his application of this to the etiology of disease. Out of Pasteur's work grew, the treatment of bacterial diseases by vaccines and antitoxic sera, and the increased knowledge of infectious diseases gained by the study of bacteriology, led to the search for protozoa as causes of disease and the demonstration of the etiological importance of the latter, led, in turn, to the development of Ehrlich's chemotherapy as a means of combating protozoan disease. But while this was the main line of advance we have seen how Pasteur influenced surgery through Lister, and how anesthesia, through the efforts of Morton came also to aid this science. So, likewise, physiological chemistry came into being, indirectly as a result of Liebig's work, but more directly as a result of the needs of physiology for a better understanding of cell composition and enzyme action, and, finally, both physiology and physiological chemistry con-