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104 the Imperial Botanic Gardens in the Southern Ural. This paper contains a general notice of the vegetation of those parts visited by him, with observations on the relations of the Flora of this region. An enumeration of the flowering plants and ferns of the South Ural, with notes on the flowering or fruiting period of most of the species, is appended.

—Les Forêts du Nord de la France aux xve, xvie, et xviie siecles.—Bull. Soc. Bot. de France, tom, vii., p. 11–14.

—On the Tribe Colletieæ, with some observations on the structure of the seed in the family of the Rhanmaceæ.—Annals and Mag. Nat. Hist. 3 ser., vol. v., pp. 76–95, 200–216, 267–73, 370–81, 482–92.

Mr. Miers prefixes to the descriptive portion of his paper a de- tailed account of the structure of the seed of Colletia dumosa, and of several species of Rhamnus, Frangula, Zizyphus, and Alphitonia.

The Colletieæ are divided into three sections.—1. Eucolletieæ, Flores apetali; fructus capsularis, dehiscens (including Notophaena, gen. nov.). 2. Chænocarpeæ, Flores petaliferi; fructus capsularis, dehiscens. 3. Clethrocarpeæ, Flores petaliferi; fructus nucumentaceus et lignosus aut membranaceus, fere semper indehiscens (including Scypliaria, gen. nov.). The genera and species (of which 21 are new), are minutely described.

—Ueber die anatomischen Veränderungen des Blattgelenkes, welche das Abfallen der Blätter herbeiführen.—Bot. Zeitung, 1860, pp. 1–7, 9–17.

Von Mohl details his observations upon the phenomena presented by various species, and particularizes certain exceptional conditions which occurred to him. Generally speaking, the essential structural change which is the immediate cause of the fall of leaves takes place in a transverse layer of the cells of the petiole. The cells of this layer usually soften, become filled with plastic contents, multiply by division, and finally their membranes separate in a determinate plane.

Ueber den Ablösungsprocess saftiger Pflanzenorgane.—Botanische Zeitung, 1850, pp. 273–7.

The author investigates the immediate causes which determine the fall of the undeveloped extremities of branches during summer; of flowers, and of floral organs. In the case of the caducous apical buds, their fall is due to the separation from each other of the starch-or protein-containing cells of a transverse divisional plane, in a manner corresponding to that obtaining in the petiole of leaves. The fall of flowers (as in Æsculus, male flowers of Cucurbitaceæ, perigonial leaves of Lilium, &c), is consequent on the rounding and mutual separation of the cells of similar divisional planes.

—Genera nova tria Apocynacearum extra-brasiliensi-americana.—Botanische Zeitung, 1860, pp. 21–3. The genera are Elytropus, Prestoniopsis, Urechites.

Species novæ nonnullæ americanæ ex ordine Apocynearum