ABIES 



259 



westward through central Michigan and Minnesota and northward along 



the eastern slope of the Rocky Mountains (Sargent). 

 Pleistocene of the Scarborough Period at Scarborough, Ontario. 

 Material altered by decay, but otherwise in original condition and not 



petrified. 



5. A. magnifica, A. Murr. 



Red Fir 



Transverse. Growth rings rather broad. The summer wood upwards of 

 one third the growth ring, the structure open throughout, but the most 

 recent tracheids much compressed radially, transition to the spring 

 wood very gradual. Spring wood open, the large, conspicuously 

 squarish tracheids uniform in very regular rows, thin-walled. Resin 

 cells present on the outer face of the summer wood, where they are to 

 be distinguished by their thin walls and somewhat advanced position. 

 Medullary rays prominent, sparingly resinous, i cell wide, distant 2-10 

 rows of tracheids. 



Radial. Rays sparingly resinous throughout and wholly devoid of tracheids. 

 Ray cells straight throughout, equal to 7-9 spring tracheids, becoming 

 much shorter in the summer wood ; the upper and lower walls thick, 

 unequal, and strongly but imperfectly pitted throughout ; the terminal 

 walls sparingly pitted in the spring wood, but becoming strongly pitted 

 in the summer wood ; the lateral walls with small, obscurely bordered 

 pits, at length becoming conspicuous and round with a prominent 

 border and slitlike orifice toward the summer wood, chiefly 2, more 

 rarely i or 4, in the summer wood reduced to i, per tracheid through- 

 out. Bordered pits in i row, elliptical, becoming much smaller 

 toward the summer wood, where the round orifice becomes narrow 

 and prolonged, coalescing to form spiral striations. Pits on the tan- 

 gential walls of the summer tracheids numerous but flat and small, 

 sometimes present on the tangential walls of the earliest spring 

 tracheids. Resin cells few, on the outer face of the summer wood, 

 nonresinous and distinguished by the transverse septa without bor- 

 dered pits; narrow and very long, usually about 20-25 /x wide, 

 350-435 p or more long. 



Tangential. Rays high, occasionally 2-seriate in part, the cells uniformly 

 broad, round, and large or oval, sometimes sparingly resinous. 



A large tree 61-76 m. high, with a trunk 2.40-3 m. in diameter. 

 Wood light, soft, not strong, rather close grained, compact, satiny, durable 

 in contact with the soil, liable to twist and warp in seasoning. 



Relative specific gravity 0.4701 



Percentage of ash residue 0.30 



Approximate relative fuel value 46.87 



Coefficient of elasticity in kilograms on millimeters . . 662. 



Ultimate transverse strength in kilograms 299. 



Ultimate resistance to longitudinal crushing in kilograms 6963. 



Resistance to indentation to 1.27 mm. in kilograms . . 1545. 

 (Sargent) 



