OLIVEU ON THE STEM OE DICOTYLEDONS. 319 



other by irregular prolongations in a radial, oblique, or 

 sinuous direction. The structure of the root of G. Turpetlmm and 

 of the stem of one or two other undetermined Convolvnlaceae is 

 described.— Hartig, Th. Bot. Zeit. 1859, 108. Wood cells in 

 bast. — Ipomaea. Mohl, H. v. XJeber d. Bau * * der Eanken- 

 und Schlingpflanzen. Tubingen, 1827, § 75. — Cuscuta europaea. 

 Unger, Fi"z. Beitrage z. Kenntniss d. parasit. Ann. Wien. Mus. 

 ii. — Cuscuta. Unger, Erz. Beitrage z. Kenntniss d. Parasit. 

 Pilanzen. 1841. tab. vi. — Chatiu, A, Compt. Eend. 1856. t. xlii, 

 269 . — also in Auatomie Comp. des Vegetaux. Livr. iii. i. 

 with figs. Noting the absence of medullary rays, of unreliable 

 spiral vessels and of a cortical fibrous layer. Modifications of 

 structure are described in C. Epith/mum, C. major, 0. densifiora, 

 C. reflexa, G. americana. In G. monogyna true spiral vessels 

 occur; also a zone of large dotted fibres.— Uloth, W. Beitrage 

 z. Physiologie der Cuscuteae. Flora, 1860, 257, 273, with figs. 

 The connection between the parasite and its prey is minutely 

 described. — Pitra, A. Ueber d. Anheftungsweise einiger phanerog. 

 Parasiten, Bot. Zeit. 1861, 72. 



AcANTHACEAE. — Tliunlergia. Mohl, H. v. Ueber d. Bau * * der 

 Eanken- und Schlingpflanzen. Tubingen, 1827, § 75. 



BiGNONiACEAE. Martius, von. Grelehrte Anzeigen. 1842, 390. — 

 Richard, Nouv. Elemens de Botanique, 1846, 152.— Biffnonia 

 Lindleijana. Mettenius. G-.,* Einige Beobachtungen liber den 

 Ban der Biguonien. Linnsea, 1847, 567. With 1 pi. The only 

 notable peculiarity in young shoots is presented by the liber, of 

 which four large bundles, isolated at right angles from each other, 

 traverse the outer layers of coi'tical parenchyma, forming longi- 

 tudinal ridges on the exterior of the stem. The rest of the liber 

 formation is deeper in the cortical cellular tissue. In cross 

 section of the adult stem it is found that the formation of the 

 wood-zone has been arrested at an early period, at foui* distinct 

 spaces in its circuit, each opposite to one of the isolated bast- 

 bujidles ; that, at these portions, the cambium layer appears 

 to have formed, principally, alternating zones of liber and paren- 

 chyma, while, over the rest, wood-cells and vessels have been 

 formed. The four alternating bark and wood formations are 

 separated radially by medullary rays of 3 or 4 series of cells, 

 between rows of which a fissure is found to have originated co- 

 extensive with the dissimilar formations. The wood is traversed 

 by wide-mouthed vessels, isolated, or in radially disposed groups ; 

 where these border on the pith, spiral vessels occur. — Treviranus, 

 Bot. Zeit. 1847, 398. Ann. Nat. Hist. Ser. ii. 1. 129. On 

 structure of Bignonia capreolata. — Graudichaud. Guillemin's 

 Archives, ii. 501. PI. 19. — also in Eecherches sur I'organographie, 

 &c. des vegetaux, tab. xiv. 4. Other species of Bignoniaceae, tab. 

 xviii. 4-10.— Voyage de la Bonite. Bot. Atlas, tab. 132. 16, 17. 

 — Schleiden. Principles of Botany, 251-2. (with figs.)— Jussieu, 



