INTRODUCTION 



It is enough to say that every part of a piece of wood consists 

 originally of cells, or closed cavities, which in the case of the 

 pores or vessels become modified into tubes : even in these the 

 remains of the original partitions are to be seen. These cells 

 are of various forms : round, polygonal, spindle-shaped, rect- 

 angular, etc., etc., and are usually characteristic of the tissue 

 they assist in forming, as will be seen when referring to each 

 special class. The chief feature of the wood of all Coniferous 

 and Broad-leaved trees is the system of rays, not only because 

 rays are never absent, but because they are a most important 

 factor in the classification of wood. 



In a piece of Beech (Fig. 128), on a transverse section, these 

 rays arise in a fine point, increase in width and again decrease 

 until they taper away again to vanishing point. By 

 observing the Tangential section, as is easily done by 

 removing the bark, it is seen that, though much shorter, 

 they preserve the same form, i.e. that of a spindle or 

 tip-cat, tapering at both ends. Laterally, in a radial section, 

 it is almost impossible to make out their shape, for they never 

 remain uninjured; still, from their form on the two sections 

 already described, their shape may be deduced. This I believe 

 to be a double-edged, double-ended blade ; something resembling 

 the outline of a fish, such as the dace or minnow, but of course 

 very much longer in proportion to its depth. It has been 

 stated by A. Mathieu (37) that the rays do not taper to a point 

 in a transverse section, but that they curve downwards, hence 

 the cut traversing the narrow upper edge of the ray causes 

 the appearance of tapering to a point. Out of many thousands 

 of radial sections of some 1,300 different species I have 

 never seen any indication of this bending of the rays ; on the 

 contrary they are always remarkably straight, as are their 

 component cells also. It must on the other hand be confessed 

 that neither has any indication of the tapering to a point in a 

 radial section been observed; the difficulty of isolating a ray 

 has so far stood in the way of a practical proof. (See Figs. 168, 

 169.) 



This discussion may seem discursive, but there is this to be 

 said, that the form of the rays is an exceedingly important 

 factor in the composition of the "figure" of timber, and a clear 

 idea upon this point will often enable one to deduce the " figure " 

 from a small fragment of wood taken in any section, such as a 

 chip from the corner of a log. 



The greater number of species of trees have merely one kind 

 of ray, but in the Oaks (Figs. 121 to 129) there are two 

 kinds, large and small. The large rays are usually very broad 

 and deep in a tangential section, and are seen to be composed 



