individuality with the existence of a single vital force, presiding over the working of all the functions? It would be necessary to reject such a hypothesis and seek the reason of vital phenomena in the properties of molecules and atoms, or else to assign a vital force in miniature to each cell. Schwann insisted that the hypothesis was both superfluous and insufficient. He could not conceive its existence unless it possessed the attributes of intelligent beings; and preferred to seek the cause of the final purpose in nature in the Creator rather than in the creature.
Schwann was just putting in press the book containing his microscopical researches and his later results, when he was invited, in his twenty-ninth year, to take the place of Windischman as Professor of Anatomy at Louvain. His position at Berlin was pleasant, but overmodest, and offered no near prospects for promotion. So he accepted the proffer, and prepared at the end of 1838 to remove. He had to meet a considerable difficulty, in the beginning of his career at Louvain, from the necessity of speaking in French; but his lectures were successful, and still form the basis of instruction in microscopic anatomy at the university. During his term here he published a memoir on the uses of the bile, the results of which, while it gave a new operation in physiological technics, have not been fully confirmed; applied Quetelet's method of statistics to physiological phenomena; and attempted the artificial production of organic elements.
In 1848, Spring, of the University of Liége, finding the combined labors of the chairs of Physiology, General Anatomy, and Comparative Anatomy too much for a single professor to perform, asked to be relieved of a part of his burden. Schwann was selected to fill the place, and was installed in November of the same year Professor of Anatomy, Spring reserving to himself the branches of osteology and myology till 1853, when the whole course came under Schwann's charge. Some opposition was expressed at first to the coming of a stranger to the university; but this soon passed away, for the brilliant reputation of the new professor, the excellence of his teaching, and the loyalty and amenity of his disposition silenced hostile comment, and won hearts to him. In later years he refused several offers of brilliant scientific positions in Germany—from Breslau in 1852, Würzburg and Munich in 1854, and Giessen in 1855. In 1858 he exchanged the chair of Descriptive Anatomy for that of Human Physiology, and in 1870 became an emeritus professor.
Clearness, order, and method are described by those who attended his lectures as the characteristic qualities of Schwann's teaching. His courses in physiology were eminently demonstrative and experimental. Laboratory work always presented a great attraction to him. He was interested in the development of