316 



WOODS OF COMMERCE. 



Spruce, a name applied originally to the Common or Norway 

 Spruce (Pice'a excelsa Link. = Pinus Abies L. = P. Picea Duroi = 

 Abies exce'lsa DC : Order Coniferce) from Pruce or Prussia, whence 

 it was obtained, and then extended to all the species of the 

 genus Pice'a and to a few other trees. Besides the fact of 

 their cones falling off whole, and other botanical characters, 



FIG. 62. Transverse section of Spruce (Picea exctlsa), one year old. 



by which the Spruces are distinguished as a genus from 

 the Firs (Abies), their wood, though varying in durability 

 according to the soil on which it is grown, has most of 

 its characters common to all the species. There is no distinct 

 heartwood, the whole being of a whitish colour : the resin-ducts 

 are few and small; and the pith-rays have tracheids with 

 bordered pits for their upper and lower rows of cells with four 

 rows of parenchyma having simple pits in the middle (Figs. 62 

 and 63). The wood is less resinous than Pine, though equal to 



