320 APPENDIX IV 



and sometimes form a pattern of oblique lines. Pith-flecks, usually abundant 

 in the Sallow or Goat-mllow {Sdlix Odprea), are present in ;S^. dlha, but appar- 

 ently absent in S. frdgiUs, 



The wood of the Goniferce, the Needle-leaved trees, known commercially as 

 " soft wood," is far simpler in structure than that of the trees of which we 

 have been speaking, as may be seen by a glance at Plates XLI. to XL VIII. 

 Its annual rings are generally well defined by the contrast of harder, heavier, 

 and darker autunm-wood against the softer and lighter spring-wood. The 

 pith-rays are so fine as to be hardly noticeable even in our highly magnified 

 plates ; and there are no trachese or pores, the wood— with the exception of 

 the pith-rays and sometimes of resin-ducts— being entirely made up of 

 tracheids. The very general presence of bordered pits on the side-walls of 

 these tracheids (see Fig. 15) renders longitudinal sections of value in the dis- 

 crimination of this group. The presence or absence of resm-ducts (Figs. 13 

 and 14) forms a useful character by which to subdivide these woods. They 

 are absent, or nearly so, in the Silver Firs {Abies), Hemlock Spruces (Tsiiga), 

 Yews (Tdxus), Jumpers (Juniperus), Kedwoods {Sequoia), Cedars {Cedrus), 

 and Cypresses {Owpressus) ; while they are present in the Spruces {Picea), 

 Larches {Ldrix), and Pines {Pinus). 



The Yew {Tdxus haccdta), (Plate XLI.), has a narrow, yellowish sapwood, 

 contrasting with its brownish-red, Mahogany-like heart. The narrow annual 

 rings are sharply defibned by a dark zone of autumn-wood. The pith-rays, 

 which are only one row of cells in width, contain some resin. In longitudinal 

 section this wood is readily recognized by the presence of spiral thickening 

 bands in the tracheids, as well as pits. 



Sequoia sempervirens, the Cahfornian Kedwood, (Plate XLII.) has a narrow 

 light amber-coloured sapwood and a uniform light red, very soft and very 

 light heart. It is usually slowly grown, the annual rings, though varying 

 considerably, being narrow. They are clearly defined by a line of thicker- 

 walled autumn tracheids. The pith -rays are very distinct with a lens, not 

 equidistant, fine, uniform, and fairly straight. Resin occurs in isolated cells, 

 resembling ruby beads. The tracheids, forming the bulk of the wood, are 

 large and thin-walled. The wood has no fragrance. 



Cedrus Lihani, the Cedar of Lebanon (Plate XLIIL), is light, soft, or 

 moderately hard, yellowish or reddish-brown, and fragrant. The rings are 

 well marked by a dense autumn zone. Pith-rays are fine, not equidistant, 

 uniform, and fairly straight. True resin-ducts do not occur ; but occasionally 

 rows of large resin-cells appear. 



In structure Picia dlha, the White Spruce of North America (Plate XLIV.), 

 resembles the Common or Norwegian Spruce (P. excelsa), represented in 

 Figs. 12 and 13. The heartwood and sapwood are alike of a yellowish white, 

 and hardly distinguishable. The broad rings, however, are very clearly 

 defined by the darker and harder zone of autumn-wood made up of radially 

 compressed tracheids (Fig. 13), and they are slightly undulating in contour ; 

 whilst in the European species this contrast of colour and hardness is not so 

 marked. The pith-rays are numerous, straight, and one cell broad. The 



