OLIVER ON THE STEM OE DICOTYLEDONS. 255 
axis, the arrangement of the woody-bundles is totally different 
from that of its allies, as is, also, the histological character of the 
tissues composing them. Apart from the form of the stock and 
general structure of the wood, which cannot be well explained 
without figures, the more remarkable features are, (1.) the isola¬ 
tion of the vascular bundles, consisting of barred vessels of small 
diameter and spirals, cambium-cells, and a remarkably large cord 
of liber; (2.) the presence, scattered through the parenchyma of 
almost the entire plant, of long, often irregularly branched, and 
very thick-walled cells, usually more or less covered with minute 
rhomboidal crystals, the composition of which is yet undeter¬ 
mined; (3.) the fine transverse barring of the very long bast 
fibres. The parenchyma forming the matrix traversed irregularly 
by the vascular bundles of the wood, is thin-walled and usually 
destitute of markings, excepting in the peduncle, cone-axis, and 
immediately around the vascular bundles of the leaf where it is 
strongly dotted or slit-marked. Disc-marked prosenchyma, cha¬ 
racteristic of Coniferae, does not occur. # (D. O.)— Ephedra. 
Meyen, F. J. F. Phytotomie, 1830, tab. xiii. 9.—-Mohl, H. v. Ueber 
den Bau der grossen getfipfelten jRohren von. Linnsea. 1831, 
593, und taf. Ann. Sc. Nat. 1832, 29, 76. The wood-cells bear 
discs not only on the surfaces parallel to the medullary rays, but 
also towards the bark and pith; thus differing from Finns , Thuja , 
Juniperus , Cycas , and Zamia. In the inner part of each annual 
ring lie wide porous tubes : these are not irregularly scattered 
through the wood, as Meyen states.—Meyen, F. J. F. Anat. und 
Phys. d. G-ewachse. 1836, tab. vi. 1-8, 10, 11. Neues System 
Pflz.-Physiologie, 1837, i. 369,379.—Schultz, C. H. Die Cyklose. 
Nova Acta Ac. Cses. L. 0. 1841, xviii. Suppl. ii. (fig.) and Finns , 
(fig.) tab. iv.— Casuarina. Kieser. Mem. sur l’organisation des 
plantes, 1814, 306.—Groeppert, H. B. Bemerkungen fiber den 
anatomischen Bau der Casuarineen. Linnaea, 1841, 747. Ann. 
Sc. Nat. Ser. ii. 18, 1, with one pi. The species observed were 
C. equisetifolia , C. stricta, O. torulosa , and herbarium specimens of 
C. glauca, C.paludosa, C. muricata , C. distyla , and C. 4^-valvis. The 
pith-cylinder is rarely more than 10-12 cells in diameter. Spiral 
vessels occur in its sheath. From the medulla proceed usually 
20-25 principal rays ( rayons grands') : rayons petits also occur in 
considerable number from each ligneous zone. Crossing the wood 
transversely from ray to ray are bands of cellular tissue similar 
in structure to the rays. These are distinguished as ‘ rayons 
medullaires concentriques ou connectifs,’ in contradistinction to 
the usual rays, ‘medullaires centrifuges.’ The cells of prosenchyma 
are narrow, thick-walled, marked with a single series of dots. 
Dotted vessels are irregularly scattered through the wood. 
Annual wood zones are not apparent. In Casuarina equisetifolia 
the transverse bars of thin-walled cells between the medullary 
* Yule N. II. R. iii. 201. 
