Contemporaries of Travers were: Abram Colles; John Cheyne (1777-1830), of Dublin, who wrote on _Diseases of Children_ and described "Cheyne-Stokes respiration." William Stokes (1804-1878), also of Dublin, who distinguished himself in 1857 by a great work, entitled _A Treatise on the Diagnosis and Treatment of Diseases of the Chest_; Robert Graves (1797-1853), Professor of Medicine in the King's and Queen's College, Dublin, who published clinical lectures of his own, besides many clinical reports in connection with Stokes. Graves was one of the first to oppose the "absolute diet" of the earlier physicians in the management of febrile maladies, and requested that his epitaph should have but one line--"He fed fevers!" "The School of Natural Philosophy" was the title applied to a system which, in Germany, ran parallel with that of Broussais, being the legitimate outcome of the medical{249} philosophy of the eighteenth century which had originated there, and also a revival of opposition thereto on the side of realism. It led into speculative extremes, which finally sobered down, because of the meaningless scholastic phrases often introduced, and thus broke a path for the subsequent enthusiasm in behalf of French positivism in medicine. Those who constituted this school were, for the most part, men of importance, but were followed by a number of imbecile representatives. Use was made of the abstract doctrine of the philosophy of identity and the imponderables, such as electricity, mechanical forces, and magnetism, contrasted with which were the dimensions of matter and certain qualities, like sensibility, irritability, etc. Perhaps the greatest influence of this teaching was in the department of embryology and physiology, where Johannes Müller displayed his remarkable activity. Among the most distinguished representatives of the natural-philosophy school was Oken (1779-1851), of Bavaria, who subsequently taught in Munich, Jena, and Zürich, and published a large work on natural history, which did much for the popularization of this science; he explained that the skull is made up from a series of vertebræ; also discovered the Wolffian bodies, and was such a power in his way that Agassiz characterized him not only as "a master in the art of teaching," but as "a courageous and ruling spirit." Others of this school were: von Walther (1782-1849), eminent as a surgeon; Dollinger (1770-1841), of Bamberg, the distinguished leader of the Old Catholics; Reil and Procliaska, anatomists; Troxler and Schelling, philosophers and anatomists; Treviranus, the microscopist; Malfatti, Kilian, Spindler; Schmidt, of Vienna; and others too numerous to mention.