APPENDIX IV 319 



areolae of soft tissue round the pores. The wood as a whole has not the silky- 

 lustre of the Maples. 



Diffuse-porous woods in which the pith-rays are not distinguishable by the 

 naked eye, comprise a hard and a soft series, the former including the Haw- 

 thorn, Pyrus, Birch, and Box. 



Grat^gus Oxyacdntha, the Hawthorn (Plate XXXVII.), is a very hard and 

 heavy, but lustreless, wood, which has been recommended as a substitute for 

 Box, but seldom comes to market. Its rings are indistinct and wavy; its 

 pith-rays very numerous ; and its pores very numerous, minute, and evenly 

 distributed, and sometimes grouped two or three together. Pith-flecks are 

 numerous in this wood. 



Whilst the genus Prunus and the rest of the Amygdalece have visible pith- 

 rays and a spring pore-zone, the Pomdcece, another Tribe of the Eosdcece, to 

 which the Hawthorn and the genus Pyrus (Plate XXXVIII.) belong, have 

 invisible rays, and are diffuse-porous. The wood of the Pear (P. comm'dnis) 

 and the very similar wood of the Apple (P. Mdlus) are destitute of pith-flecks, 

 but are liable to warp and crack. Their rings are clearly marked by a greater 

 crowding of the minute pores in the spring-wood and their absence in the fine 

 line of dense autumn-wood. The pith-rays are numerous, not quite equi- 

 distant, fine, and undulating ; and the pores are often grouped two to five 

 together, or in loose " worm-like " lines. The generally similar wood of the 

 sub -genus 86rbus, including the Powan, etc., in which pith-flecks do occur, is 

 stated to season better than Apple or Pear wood. 



The tough, close-grained and moderately hard woods of the Birches have a 

 fairly uniform type, of which we may take Bitula linta, the Canadian Birch 

 (Plate XXXIX.), as a representative. The rings are tolerably clearly marked 

 by a fine Hne of autumn-wood : the pith-rays are numerous, not equidistant^ 

 undulating, fine, and uniform in thickness; and the pores are of medium 

 size, so as to be visible " like fine white flour sprinkled over the surface of a 

 soHd section," evenly distributed, but not very numerous, and mostly sub- 

 divided into groups of two to ^ye or more together. Pith-flecks occur mostly 

 near the centre — i.e., in the older wood. 



Among the soft-wooded broad-leaved trees few are of much importance a& 

 timber; but Sdlix dlha, the White Willow (Plate XL.), or, perhaps, rather 

 >S^. frdgilis, the Crack Willow, is exceptionally valuable for cricket-bats. 

 Apart from colour and physical tests, there is nothing in the microscopic 

 structure of Willow-wood that will suffice to enable us to discriminate species 

 or qualities. 1 The wide rings are clearly defined, with a somewhat undulating 

 contour, where the fewer and smaller pores of the denser autumn -wood con- 

 trast with the numerous larger ones of the spongy spring-wood. The pith- 

 rays are very numerous, very fine, and nearly equidistant, being rather more 

 than the width of one large pore apart and undulating sHghtly to avoid these 

 pores. The pores are very numerous, small, oval, occasionally subdivided, 



1 Stone, Timbers of Commerce p. 236 ; and an admirable, fully illustrated paper 

 on "The Variations of Sdhx dlha,'' by E. E, Pratt, Quarterly Journal of Forestry, 

 vol. i. (1907), pp. 320-337. 



