104 BIBLIOGRAPHY. 



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. 



Melicocq,, Baron. — Les Forets du Nord de la France aux xv e , xvi e , et 

 xvii e siecles. — Bull. Soc. Bot. de France, torn, vii., p. 11-14. 



Miers, John. — On the Tribe Colletieae, with some observations on the 

 structure of the seed in the family of the Rhanmacese. — 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, Zhyplms, and Alpliitonia. 



The Colletiece are divided into three sections. — 1. Eucolletiece, 

 Flores apetali ; fructus capsularis, dehiscens (including Notophaena, 

 gen. nov.). 2. Chcenocarpece, Flores petaliferi ; fructus capsularis, 

 dehiscens. 3. Clethrocarpece, Flores petaliferi; fructus nucumen- 

 taceus et lignosus aut membranaceus, fere semper indehiscens (in- 

 cluding Scypliaria, gen. nov.). The genera and species (of which 21 

 are new), are minutely described. 



Mohl, H. von. — Ueber die anatomischen Veranderungen des Blattge- 

 lerikes, welche das Abfallen der Blatter herbeifuhren. — Bot. Zei- 

 tung, 1860, pp. 1-7, 9-17. 



Yon 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 Ablosungsprocess saftiger Pflanzenorgane. — Bota- 



nische 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 man- 

 ner corresponding to that obtaining in the petiole of leaves. The 

 fall of flowers (as in JEsculus, male flowers of Cucurbitacese, peri- 

 gonial leaves of Lilium, &c), is consequent on the rounding and 

 mutual separation of the cells of similar divisional planes. 



Mueller, J. — Genera nova tria Apocynacearum extra-brasiliensi-ame- 

 ricana. — Botanische Zeitung, 1860, pp. 21-3. The genera are Ely- 

 tropus, Predoniopsis, Urechites. 



Species novas nonnullae ainericanae ex ordine Apocynearum 



