OLIVER ON TUE STEM OF DICOTYLEDONS. 325 



of liber ; of a generative layer composed of two kinds of elements, 

 masses of whicli ai'e also variously disposed in tlie wood ; of me- 

 dullary rays, and intra-medullary, fibro-vascular fascicles. Dee- 

 ringia difters remarkably in some respects, tlie wood consisting of 

 isolated, fibro-vascular bundles, completely surrounded by pa- 

 renchyma, in wliich they are arranged in concentric circles. These 

 bundles are separated radially by the broad medullary rays, con- 

 centrically by layers of cells apparently proceeding from them 

 and identical with them in structure. 



Phttolaccaceae. — Phytolacca dioica. Martins, C. Dela Croissance 

 du Bel Sombra. Eev. Hort. 1855, 122. Noting the formation 

 of seven ligneous layers in five months, in the stem. — Treviranus, 

 L. C. Noch Etwas iiber den Stammbau der Phytolacca dioica. Bot. 

 Zeit. 1856, 833. The spongy wood consists of concentric, unequal 

 fibrous layers, separated by intermediate zones of cellular tissue. 

 Vascular bundles occur in the pith. Tlie structure of the wood- 

 zones, &c. is briefly described, and compared with that of allied 

 orders. — Nageli, C. Beitrage z. Wissenschaft. Botanik, i. 14. Tlie 

 structure of the stem is minutely described ; it is selected as the 

 type of those Dicotyledons which possess successively limited 

 rings of cambium tissue ia ' Epenchyma.' — Regnaidt, Ann. Sc.Nat. 

 Ser. iv. xiv. 139. Phytolacca icosandra. The fibres of the corti- 

 cal zone exterior to the 'couche generatice' terminate abruptly by 

 plane surfaces . The wood consists of fibro-vascular masses, which 

 regularly alternate with the medullary rays ; these are nearly 

 equal to them in size, composed of thickened cells pierced with 

 numerous minute canals. The woody bundles are formed of much 

 thickened and very minutely dotted parenchyma. Young stems 

 have but one wood zone ; in older stems another is superimposed, 

 with this remarkable alternation that the fibro-vascular bundles of 

 the external zone continue the medullary rays of the inner. P. escu- 

 lenta presents a similar structure. Rivina laevis is also described. 



EuPHORBiACEAE. — Euphovhia. Schultz, C. H. Die Cyklose, Nova 

 Acta, 184'1, xviii. Suppl. ii. tab. v. vi. — E. erosa. Link. H. F. 

 Anatomia Plantarum, 1843, tab. ix. 4, x. xi. — Schacht, H. Die 

 Sogenannten MUchsaft-Gefasse der Euphorbiaceen u. s. w. sind 

 Milchsaft fiihrende, nicht selten verzweigte Bastzellen. Bot. 

 Zeit. 1851, 513. Bast-cells of.— Criiger, H. Bot. Zeit. 1850, 

 126. Observation on Structure of Omphalea. — Buxus. Baillon, 

 H. Monographic des Buxacees, 1859, 8. The relation of the 

 quadrangular form of the stem to the development of woody 

 fascicles in the cortical layers from each pair of leaves. The 

 structure of the adult wood is described and figiu'cd. — Pachy- 

 sandra, p. 10. Structure of the rhizome. — Buxus. Schacht, H. 

 Der Baum, 195. — Sarcococca, Baillon, H. Monographic des 

 Buxacees et des Stylocerees, 1859. Structure des rameaux, p. 7. 

 The stem presents the usual anatomical structure of Dicotyledons. 



Garryaceae. Lindley, J. Bot. Register, xx. 1686. also Ann. Sc. 



