OLITEE ON THE STEM OF DICOTYLEDONS. * 311 



EnizoPHOEEAE. Sclileiden, Principles of Botany, (pith.) 65. 



Halorageae. — Trapa natans. Barneoud, F. M. Sur Tanatomie et 

 I'organogenie du Trapa natans, L. Ann. Se. Nat. ser. iii. 9. 227. 

 (figs.) In adult stems the vascidar bundles of the medullary 

 sheath, consisting of wide annular vessels, are numerous, forming 

 a continuous circle. There are no unrollable spiral vessels.— 

 Cucurhita, Bryonia. Kieser. Mem. sur 1' organisation des plantes, 

 1814. tab. 6—10, 12.—Cucurbita. Mohl, H. v., Bot. Zeit. 1855, 

 889. On liber of. — Nageli, C. Ueber die Siebrohern von Sit- 

 zungsb. H. b. Ak. Mlinchen, 1861, 212. 



Passiflobaceae. Mohl, H. v. Ueber d. Bau * * der Eanken und 

 Schlingpflanzen, Tubingen, 1827. § 75. 



Papataceae. Criiger, H., Bot. Zeit. 1851. Observation on the 

 structure of Garica Papaya. 



PoETULACEAE.— Povtulacaria. Link, H. F. Icones Selectae, 1839. 

 Fasc. i. vi. 5-14. — Eegnault, Ann. So. Nat. Ser. iv. xiv. 106. Tali- 

 num speciosum possesses isolated liber bundles, a fibro-vascular wood 

 zone interrupted transversely and obliquely by belts of thinner 

 tissue (arrested as it were in their development), and medullary 

 rays. The prosenchyma of the wood is punctate chiefly towards 

 the rays. The structure of Anacampseros., Claytonia, Povtula- 

 caria, and Portulaca, more or less diverse from the above, is 

 described. 



Pakon"schieae. Eegnault. Ann. So. Nat. Ser. iv. xiv. 106. Parony- 

 chia bonariensis presents a continuous circle of elongated, thick- 

 walled cells representing liber, exterior to the wood, which is 

 formed in two distinct zones. Tlie inner consists of prosenchyma 

 uninterrupted by medullary rays, with numerous vessels sur- 

 rounding the pith : the outer, of ligneous fibres and vessels, not 

 in a continuous circle, but in uninterrupted, radiating plates. The 

 vessels are regularly dotted, as also the wood-cells, between which 

 are very minute, rounded cavities, arranged in regular series 

 along the cells. Modifications of structure in Anychia dicliotoma, 

 Telephium Imperati, and Corriyiola littoralis are described. 



Teteagoniaceae. Eegnault. Ann. Sc. Nat. Ser. iv. xiv. 101. In 

 Tetragonia expansa, hber is absent. The wood, consisting of pro- 

 senchyma traversed by numerous vessels, in adult stems presents 

 an inner continuous zone uninterrupted by medullary rays. Ex- 

 terior to this, towards the angles of the stem are successively 

 superimposed independent masses, forming from two to five incom- 

 plete belts. These isolated woody masses are separated concen- 

 trically by zones of generative cells. 

 Mesembrtaceae. Eegnault. Ann. Sc. Nat. Ser. iv. xiv. 95. The 

 group offers a peculiar epidermal structure. The liber-layer and 

 medullary rays are absent. Cords of tissue corresponding to 

 portions of the ' couche generatrice' occur in the wood, on the inner 

 face of which, around the pith, are vessels, chiefly spiral, arranged 

 in radiating rows, sometimes isolated, sometimes in fascicles. The 



