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THIS part includes four papers. The first is by W. O. Focke, on the natural divisions and geographical distribution of the genus Rubus. The characters chiefly discussed are:—1. Mode of growth or habit. 2. Forms of leaf which are very numerous: the duration of the leaf being also variable. 3. Characters derived from the stipules, which are considered of great value. 4. Inflorescence; and 5. the Structure of the flower. The number and size of the parts of the calyx and corolla vary, as also the colour of the corolla. The stamens vary in closely allied species, and while most of the species are hermaphrodite, some are unisexual. The structure of the gynœcium is very varied, the number of carpels being five or six in some, as in R. dalibarda, or above 100, as in R. rosæfolius. The hairs (trichomes) on the different parts of the plant are very numerous and remarkable for the variety of structure shown; no other group, except perhaps some Solanaceæ, approaching the Rubi in this particular. In regard to the geographical distribution the most important points are.:—1. The characteristic difference in the Rubi of Eastern Asia and Europe. 2. The predominance of European forms in the Atlantic, and of East Asian forms on the Pacific side of America. 3. The occurrence of south Chinese and north Indian types in Mexico and Peru. These peculiarities Focke would explain on geological grounds.Botanische Jahrbücher für Systematik Pflanzengeschichte und Pflanzengeographie.Herausgegeben von A. Engler. Erster Band, zweites Heft. (Leipzig: Wilhelm Engelmann, 1880.)