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316 philosophy, especially in regard to the doctrine of the metamorphosis of plants. Furthermore, he succeeded in establishing the principles of anatomy so clearly that a rational system of morphology became possible for the first time. So important and basal were his demonstrations concerning the real nature of the primordial utricle that by many botanists he is said to havediscovered protoplasm (1846). Von Mohl, with Schlechtendal, established the Botanisclie Zeitung in 1842. The list of his works includes ninety titles, embracing subjects in every department of the science. During his administration at Tübingen the garden was enlarged by three additions, to its present dimensions, occupying an irregular tract of land on both banks of the Ammer; important additions were made to the glass houses in the garden, and the institute building was erected in 1846. Perhaps no greater tribute can be paid to von Mohl's broad conception of the scope and needs of botany than the fact that this institute building erected fifty years ago, remains practically unaltered to the present day, and is still found fairly available for the purposes of modern investigation.

Upon the death of von Mohl, in 1872, he was succeeded by Hofmeister, who died after having held the post but five years. Hofmeister had perhaps accomplished his more important results before his stay at Tübingen. Like von Mohl, he used an inductive method of investigation, and he as well made enormous contributions to the material facts upon which many of our present generalizations in morphology rest. The results of the investigations published in his Vergleichende Untersuchungen in 1849 remain to-day superior to anything achieved in descriptive botany. To Hofmeister must be ascribed, among other important embryological results, the discovery of the alternation of generations in plants, and by the use of his phylogenetic mode of study the ideas concerning natural affinities of the groups of cryptogams and phanerogams underwent an almost total alteration. His establishment of the genetic relationship of these great subdivisions resulted in the overthrow of the prevailing belief in the constancy of species.

Prof. Simon Schwendener succeeded Hofmeister as director of the institute and garden in 1877. He, as well as his two successors, are still in the midst of active work, and it is by no means easy to forecast the final value of the results of their investigations upon the development of the subject. Schwendener has made very important contributions to the biology of lichens, phyllotaxis, besides a long series of contributions of the first rank in the domain of morphology and physiology. Among these his Mechanische Princip in der Bau der Monocotylen is of the greatest importance. Schwendener remained but a year at Tübingen, going