OLITER ON THE STEM OF DICOTTLEBOXS. 301 



Indica, i. p. 167. Tlie authors endorse generally M. Deeaisne's 

 proj)ositions, and point out that though closely allied genera have 

 often very similar wood, so have more distantly allied ones 

 (Limncia, Pacliycjove, — Coscinium, Anamirfa), while close allies 

 sometimes differ very materially (Tinospora, ParalcEiia). In the 

 numerous genera examined in respect of stem structure, the 

 pith was found to foi'm a very varying proportion to the diameter 

 of the stem, from one-fifth (FarabcBna) to three-fourths (Aspido- 

 caryn). From the centre towards the wood bundles the cells 

 become denser, vertically elongated, and truncate at their ex- 

 tremities. The wood-wedges vary in number in different species, 

 from about twelve (Glusauipelos) to seventy (Coscinium). They 

 consist of dotted pleurenchyma traversed by barred vessels. The 

 medullary rays are usually narrow and often dense. The liber 

 bvmdles exterior to each wedge, more or less lunate and isolated, 

 or sometimes confluent. The structure of the stem (usually 

 several years of age) is described in the following genera, — 

 Coscinituii, Aspidocarya, Parahcena (sagittata), Tinospora {crispa), 

 Anamirta, TiUacora, Limacia {velutina, ohionga, ciispidata) , Coccu- 

 lus (Leceha, villosus), Pericampylus, Stepliaida (^rotunda, elegans), 

 Cissampelos (Pareira), Cyclea (populifoUa), Pachygone, Fihraitrea 

 (th\ctoria, ? hamatocarpd), Tinomisciam, Pycnarrhena. — Clypcea. 

 Griffith. Notulse iv. 305—319. — Cocculus. Martins von, Grelehrte 

 Anzeigen, 1812, SS7.— Cocculus laurifolius. Lindley, J. Introd. 

 Botany, i. 214, (with figs.) — (C. palmatus, in text). Schacht, 

 H. Die PflanzenzeUe, p. 281, tab. six, Der Baum, pp. 95, 

 199. — Nageli, C. Beitrage zu Wissen. Botanik, i. 16. 

 Selected as typical of those Dicotyledons which have successively 

 limited rings of cambimn tissue in protenchym.*— Eadlkofer, 

 L. Ueber dans anomale Wachsthum des stammes bei Menis- 

 permeen. Flora, 1858, 193. Ann. Sc. Nat. Ser. iv. 10, 

 161. Eeferriug chiefly to the second generation of cambium 

 tissue in the cortical parenchyma exterior to the liber zone of 

 the first wood bundles, — originating the new and concentric for- 

 mation of woody tissue in Cocculus laurifolius. — Schacht, H. 

 Lehrbuch, ii. 57. — Menispermiim. Eichard, Nouv. Elemens de 

 Botanique, 1816, 154.— Mohl, v., Ueber d. Bau * * der Eanken- 

 und Schlingpflanzen. Tubingen, 1827, § 75. 

 Berbekidaceae. — Podophyllum, Bipliylleia. Brown, E. in Tuckey's 

 Congo. 442 (in note). ^ — Agardh. Theoria Systematis Plantarum,75. 

 On Structure and arrangement of the vascular bundles. 



* Nageli (1. c.) distinguishes two tissues, the cells of which undergo division. 

 That of which each organ primarily consists, and which is also often active to a late 

 period if not during its entire lifetime, he terms Mtristem. The other tissue is 

 Cambium. The original Meristem and all tissues developing immediately fi-onr it he 

 calls Frotenchtjm. Cambium, and all tissues directly or indirectly derived from it, 

 Epenchijm. This important essaj' refers especially to the relations subsisting be- 

 tween the position of the leaves, and the arrangement of the vascular cords in the 

 stem. 



