THE DOUGLAS FIR 101 



and light in weight, or it may be red, coarse-grained, 

 and heavier. The wood is close, straight and regular 

 in grain, firm, tough, and elastic, not in the least liable 

 to warp, and very durable. In appearance it more 

 nearly resembles the wood of the Canadian Red Pine 

 (Pinus resino'sa Sol.) than any other species ; but, 

 under the microscope, a longitudinal section shows 

 a structure that distinguishes it from all allied woods. 

 Its " tracheids," or elongated vessel-like elements, 

 have spiral lines of thickening, especially in the 

 spring- wood of each annual ring. Such spiral thick- 

 ening occurs throughout the somewhat similiar 

 wood of the Yew ; but the Yew is non-resinous, while 

 the Douglas Fir produces an abundance of resin. 

 The transverse section shows the sap-wood and heart- 

 wood, resembling those of the Larch, but that the 

 latter is of a more rosy red. The annual rings are 

 sharply defined by the broad and darker band of 

 autumn- wood. This character places the wood of the 

 Douglas Fir commercially with the " Hard Pines." 

 The bark, thin, smooth, and greyish on young shoots 

 and warty with resinous pustules a little later, 

 becomes from three to five inches thick on old trees, 

 splitting into broad, rounded ridges and breaking up 

 at its surface into reddish-brown scales. Through 

 its longitudinal fissures it discloses a redder inner 

 bark. 



In the leaves, and to a less extent in the cones, we 

 have those resemblances and differences which justify 

 us in making separate genera for the Hemlock Spruces 

 and the Douglas Spruce, and at the same time excuse 

 the use of the word Spruce in their popular names. 



