264 THE UTILISATION OF WOODLAND PRODUCE. 



I. As regards Anatomical Structure, the woody tissue of 

 trees consists of (1) woody fibres, (2) wood-vessels, and (3) wood- 

 cells, with a framework of cellulose. (1) The woody fibres are 

 elongated, pointed at both ends, and thick- walled ; and they 

 are formed of hard tissue (scler-enchyma) with walls dotted with 

 small pits, and of tubes (tracheids) with large internal spaces 

 (lumina), whose walls are dotted with large bordered pits ; and 

 sometimes there is also a subordinate form of wood fibre shaped 

 like true hard tissue, but filled with protoplasm, starch, and 

 other substances. (2) The wood-vessels, seen as pores on making 

 a transverse section, are long narrow tubes closed at both ends, 

 with thin walls and large lumina. (3) The wood-cells forming 

 soft tissue (parenchyma) are thin-walled, more or less cubical, 

 and mostly with flattened ends ; and they are chiefly found 

 near the vessels, where they serve for storing reserve nutrients 

 (starch, &c.) for reproductive purposes (new foliage, flowers, 

 fruit, &c.), while the sap is conveyed through the woody fibres 

 and the vessels. 



The wood of broad-leaved trees contains all the above kinds 

 of woody tissue, while that of Conifers differs from it in having 

 no large pores (wood-vessels). Hence, the larger the relative 

 proportion of hard tissue, the heavier, harder, and stronger is 

 the wood of any given kind of broad-leaved tree ; and the larger 

 the proportion of thick - walled tracheids with small lumina 

 produced during the warm summer weather, as compared with 

 the thin-walled tracheids with large lumina forming the softer 

 inner zone produced in spring, the heavier, harder, and stronger 

 is the wood of any given kind of Conifer. In Conifers, wood- 

 cells are found only around the resin-ducts in the AbietineaB, 

 and are sparsely scattered throughout the tracheids in the other 

 kinds. But both broad-leaved and Conifer trees have medullary 

 rays, formed of wood-cells, extending radially from the central 

 pith (or some annual ring near it) to the bark, which serve 

 partly for storing reserve nutrients in winter (for leaf-produc- 



