seeking the solution of these great problems, admits that the only true scientific system must be one in which the thought, the intellectual structure, rises out of and is based upon facts. The great merit of the physio-philosophers consisted in their suggestiveness. They did much in freeing our age from the low estimation of natural history as a science which prevailed in the last century. They stimulated a spirit of independence among observers; but they also instilled a spirit of daring, which, from its extravagance, has been fatal to the whole school. He is lost, as an observer, who believes that he can, with impunity, affirm that for which he can adduce no evidence. It was a curious intellectual experience to listen day after day to the lectures of Oken, while following at the same time Schelling's courses, where he was shifting the whole ground of his philosophy from its negative foundation as an a priori doctrine to a positive basis, as an historical science. He unfolded his views in a succession of exquisite lectures, delivered during four consecutive years. "Among my fellow-students were many young men who now rank among the highest lights in the various departments of science, and others, of equal promise, whose early death cut short their work in this world. Some of us had already learned at this time to work for ourselves; not merely to attend lectures and study from books. The best spirit of emulation existed among us; we met often to discuss our observations, undertook frequent excursions in the neighborhood, delivered lectures to our fellow-students, and had, not infrequently, the gratification of seeing our university professors among the listeners. These exercises were of the highest value to me as a preparation for speaking, in later years, before larger audiences. My study was usually the lecture-room. It would hold conveniently from fifteen to twenty persons, and both students and professors used to call our quarters "The Little Academy." In that room I made all the skeletons represented on the plates of Wagler's "Natural System of Reptiles;" there I once received the great anatomist, Meckel, sent to me by Dollinger, to examine my anatomical preparations and especially the many fish-skeletons I had made from fresh-water fishes. By my side were constantly at work two artists; one engaged in drawing various objects of natural history, the other in drawing fossil fishes. I kept always one and sometimes two artists in my pay; it was not easy, with an allowance of 250 dollars a year, but they were even poorer than I, and so we managed to get along together. My microscope I had earned by writing.