68 NATURAL mSTOriY OF I'LAXTS. 



lived but a few months)' are usually better developed as they 

 aj)proach the centre of the stem. In the Hellebores" and Anemones,' 

 the bundles, though of different ages, may form an apparently single 

 circle round a voluminous pith. In several herbaceous species has 

 been especially described the layer of cells called "protective sheath."* 

 The axes of Hanuncuhicece are often, too, remarkable for the poverty 

 of their tracheal system. Moreover, a certain number of plants have 

 always been pointed out in this order as exceptional in the consistency 

 of the stem and branches being woody to a certain extent ; these are 

 chiefly the so-called " Tree-Pa?onies," Xanf/torhiza, and Clematis. The 

 woody portion of the stem of Pceonia Moutan presents hardly any- 

 thing peculiar in its anatomy. The thick pith is surrounded by a 

 fresh ring of wood each season. The liber is, on the contrary, very 

 scanty, and the outer cellular layers of the bark are the seat of slow 

 and ill-marked exfoliation, much better seen in Xauthorliiza, and still 

 better in Clematis. In the former, beneath many layers covering one 

 another with great regularity, and in old brandies alternately white 

 and brownish — that is, dead and ready to peel off — may be seen a 

 layer of moniliform appearance, made up of cells, and gorged with a 

 limpid yellow colouring matter." This structure, which is essentially 

 constant, assumes a high degree of distinctness and regularity in 

 Clematis, because the leaves are opposed, or verticillate ; and it has 

 here attracted the attention of very many observers.* In the 

 hexagonal stem of Clematis may be seen a pith of no great thickness, 

 surrounded first by six, and then by ten, fibro-vascular woody 



' In the luTbaccous shoots of Larkspurs a '' Caspaht, in Priii//.<iliciin's Jahrhuch. (ISGl), 



month old we may find them of three, four, or iv. 101. 

 five successive ages. * Tliis yellow liquid is found in the young 



' Link, Icon. Bol. Anal. (1857), ii. xi. 1, 5. wood, thougli of a paler tint. The lil)er of little 



— \. Dumas, op. cit., 5-23, t. 1, 2. — In 11. thickness, is incompletely divided into as many 



fi£liduii the pith is enormous, formed of cells closely j)atked segments, as there are sectors of 



arranged in rows in every direction, so as to the wood (whose eoiripact libres are minutely 



form a network of beaded fibres separated by jiunctate), separatcnl l)y the me<lullary rays, 



irregidar jiassages. The tibro-vascular bundles The cells of the pith are also punctate, 

 in a bhiKit of a single season are numerous ; they • UuNUKSllAOEX, ex Mdiu. (Ann. Sc. Nat., 



are remarkable for having the whitish woody ser. 2, ix. 2'jr>).— Dl'TUOCHET, AtiToUs. drs. 



fibres surrounding the vessels on tlie sides as well 7V//c7. (Mt'm. iliis. (1S21), vii. 3U7, t. 16, f. 



as external to them. Tin- peduncle of 7/. int/er 4-7). — (Jikoit dk lii'ZAUElNOUES (Ann. Si: 



lias the same fundamental organi/.ation. The iVVi/., st'r. 1, xxx. t. 7, tigs. 3, 4; st'-r. 2, 1, l.'l>, 



Hub-epidermic corticid cells arc often gorged with t. 5, tig. 1).- Schi.kidkn, (irun<lzu<ir if. If'i.ss. 



pink colouring matU-r. J]o(. ii. lOtt, tig. 1 15. — CircKKTT, Jlitlol. Hi. — 



» VAT'l'liLI., 6'. iib. d. piriph. Wavlmlhum d. CakI'KNTKU, Mirntm: (lH5(i). 131. t-Ut (? ev 



(hfiUhund. (1855), 21, t. 1. — The arrangement Oi.lV.). — (SuiKFiTii & Hknfuky, J/iVro'/r. Uirl. 



of the buudieH in the Anemoueg is funda- (185(5), 75, 387, (Wli. — A. OuiLLAKD (Ahh. 



menUiUy the same as in tlie aiuiual Larkspurs. Sc. A'al., »or. 3, viii. t. xvi.). 



