“ He recognized under the name of “primordial utricle” the protoplasmic lining of the vacuolated cell, and first described the behaviour of the protoplasm in cell-division. These and other observations led to the overthrow of J. M. Schleiden’s theory of origin of cells by free-cell-formation. His contributions to knowledge of the cell-wall were no less remarkable, he held the view now generally adopted of growth of cell-wall by apposition. He first explained the true nature of pits, and showed the cellular origin of vessels and of fibrous cells ”

“ This seems to have determined his career as a botanist, and he started in 1828 those anatomical investigations which continued till his death. In 1832 he was appointed professor of botany in Tübingen, a post which he never left. Unmarried, his pleasures were in his laboratory and library, and in perfecting optical apparatus and microscopic preparations, for which he showed extraordinary manual skill. He was largely a self-taught botanist from boyhood, and, little influenced in his opinions even by his teachers, preserved always his independence of view on scientific questions. ”