CLASSIFICATION OF CONIFEROUS WOODS. 51 



(ii) Canals in groups or lines of 8 30 : tracheids with 

 spirals, otherwise resembling Larch. Douglas Spruce, 

 Pseudofaiiga. 

 b. Resin-canals numerous, evenly distributed. Knots in 



regular whorls. Finns. 



(i) Wood tolerably hard and firm : transition from spring 

 to autumn wood abrupt : resin-canals more numerous 



Fio 30. Radial section of Scots Fir (Plnut sylvtstrig). Magnified 100 

 times, a, narrow tracheids of autumn wood with small bordered pits on 

 their radial walls ; b, broad spring tracheids ; ct/, resin-duct lined with 

 epithelium ; (, parenchyma of pith-ray with large simple pits ; /, tracheids of 

 pith-ray with small bordered pits and dentate projections. From Hal-tig's 

 Timbers and how to know them, by permission of Dr. Somerville and Mr. David 

 Douglas. 



in autumn wood : heartwood reddish : tracheids of 

 pith-ray with dentate projections, when seen in 

 radial section (Fig. 30). Hard Pines. 



* 1 or 2 simple pits on radial wall of each tracheid of 

 pith-ray. " Norway pine " of U.S.A., Pinus resindsa. 



** 3 to 6 such pits. 



