NEW ZEALAND FLAX.—_Phormium tenax._ Order, _Lineaceæ_. Fibro-vascular bundles of the leaves. Microscopic characteristics.—Length of fibres, 9 mm., diameter 0·016 mm., ratio, 560. Fibres are fine, regular and smooth; the walls are uniform, central canal small, extremities vesicular. The fibres have little cohesion in the bundle. Sections round or polygonal. Illustrated in Fig. 4, p. 35. Micro-chemical reaction.—Yellow, with iodine solution. Characteristic deep red colouration with concentrated nitric acid (Müller). General chemical characteristic.—Ligno-cellulose. It contains 86·3 per cent. of cellulose. MANILLA HEMP.—_Musa textilis_, Abacá. Order, _Musaceæ_. Fibro-vascular bundles of leaves. Microscopic characteristics.—Length of fibres, 6 mm.; diameter, ·024 mm.; ratio, 250. Fibres, white lustrous; the walls are uniform; central cavity large and very apparent. Fibres easily detached. {60} Sections round or polygonal. Illustrated in Fig. 14: _a_, section of bundle of fibres; _b_, fibres seen longitudinally; _c_, ends; mag. 300. [Illustration: FIG. 14.] Micro-chemical reaction.—Yellow with iodine solution. Composition (Hugo Müller):— Cellulose 64·07 Fat and wax ·62 Aqueous extract ·96 Lignin and pectous substances 21·60 Water 11·73 Ash 1·02 WOOD.—Nearly, if not the whole of the chemical wood pulp used in this country is obtained from trees belonging to the order _Coniferæ_ (Gymnospermæ), more particularly from the genera _Abies_ and _Pinus_. In America, however, poplar and other woods are largely employed. The coniferæ yield a larger proportion of pulp than most other woods, the individual fibres, moreover, are longer, and for these reasons it is generally preferred. On the other hand, however, poplar is more readily acted upon by reagents. Fig. 15 gives the microscopic appearance of {61} the fibre of the common white fir. It is characterised by the presence of numerous pitted vessels (Fig. _a_). [Illustration: FIG. 15.] Pine wood consists essentially of a compound cellulose, resembling in most of its properties the jute fibre (see p. 16). With iodine solution it gives a deep yellow colour. The chemical composition of some of the more important woods will be seen from the following analyses. (Müller.) ----------------+------+------+-----+-----+------- |Birch.|Beech.|Lime.|Pine.|Poplar. +------+------+-----+-----+------- Cellulose[8] | 55·52| 45·47|53·09|56·99| 62·77 Resin | 1·14| 0·41| 3·93| 0·97| 1·37 Aqueous extract | 2·65| 2·41| 3·56| 1·26| 2·88 Water | 12·48| 12·57|10·10|13·87| 12·10 Lignin | 28·21| 39·14|29·32|26·91| 20·88 ----------------+------+------+-----+-----+------- [Footnote 8: For the amounts of cellulose actually obtained in practice see p. 77.]