OLIVER ON THE STEM OF DICOTYLEDONS. 313 



ternal anatomy of M. microcephalus. — Opvntia. Link, H. F. 

 Icones Anat. Bot. 1837. Ease. ii. xv. 4-5. 



!RiBESiACEAE. — Bibes. Hanstein, J. Ueber den Zusamnienliang der 

 Blattstellung mit dem Bau des Dicotylen Holzringes, Prings- 

 heim's Jalirb. i. tab. xvi. 10. 



Alangiaceae. Lindley, J. Veg. Kingdom, 720. 



Ceassulaceae. — Sevipervivum, and other Crassulaceae. Brongniart, 

 A. Obs. sur la Structure du Sigillm'ia, ^c. Arch, du Museum, 

 (1839) i. 437. On the absence of true medullary rays, and rela- 

 tion of medullary vascular bundles to the leaves. — Crassula por- 

 tulacea. p. 445. Destitvite of a ligneous zone. The fascicles of the 

 medullary sheath, consisting of spiral vessels and spiral, annular 

 and reticulate ducts, increase in number and size without admix- 

 ture of wood-prosenchym. — Cotyledon. Link, H. F. Icones Se- 

 lectae, 1839. Ease. i. vii. 1-2.— Wiegmann's Arch. 1839, 224. A. 

 N. H. iv. 241. Wood formed of prosenchym destitute of vessels, 

 traversed by vertical cords of thin-walled parenchym which include 

 spiral vessels. — Lindley, J. Veg. Kingdom, 345. — Sedum. Henry, 

 A. Ueber die Bildung der Wurzel-zasei'n v. S. Telephium, ^o. 

 Verh. N. H. V. 1860-1. Chiefly referring to the structure of the 

 tuberiform root-fibres. That of the stem which offers no pecu- 

 liarity, is described. — Eegnault, Eecherches sur les affinites de 

 Structure des Tiges des plantes du groupe des Cyclospermees. 

 Ann. Sc. Nat. Ser. iv. xiv. 87. — Sempervivum arbor eum. A 

 woody stem several years of age presents a cellvilar cortical zone, 

 including outer suberous and inner herbaceous layers. Wood con- 

 sisting of crowded, thick- walled and irregularly dotted prosen- 

 chyma, traversed by isolated vessels. Zones, consisting of vessels 

 and elongated, quadrangular, delicate cells, destitute of markings, 

 are disposed concentrically through the wood, which is destitute 

 of medullary rays. Vascular bundles, consisting of annular ves- 

 sels, unroUable spirals and elongated cells occur in the wood 

 around the pith, which offers no unusual character. Other 

 Crassulaceae present a similar type with modifications noted in 

 Rocheafalcata, Sempervivum Haivorthi, S. leucohlepharum, Sedum 

 deltoideum, S. oxypetalum, Crassula portulacea, C. ruhens, Jlm- 

 hilicus pendulinus. The Order is generally characterised by 

 the absence of liber, and of medullary rays in fully developed 

 wood ; by the presence of cords of soft, fibroid cells and vessels 

 (corresponding to isolated portions of the generative zone) in the 

 midst of the wood, and the prevalence of parenchymatous tissue, 

 giving the character of succulence to the group. 



Begoniaceae. Link. H. F. Anatomia Plantarum, 1843, tab. 

 ii. 4-5. Figures of pith cells. — Treviranus, Bot. Zeit. 1847, 

 398. Ann. N. Hist. Ser. ii. i., 29. (Eeport by Henfrey.) On the 

 unsymmetrical arrangement of the wood-bundles in climbing 

 species. — Vaupell, C. liber d. peripherische Wachsthum d. 

 G-efassbiindel, &c. Leipsic, 1855, 28. tab. 1. — Hildebrand. De 



