ABIKS 255 



Pits on the lateral walls of the ray cells 1-4, in the mar- 

 ginal cells rarely 5, per tracheid. 



Upper and lower walls of the ray cells strongly pitted 

 throughout. 



2. A. lasiocarpa. 



Pits on the lateral walls of the ray cells 1-2, or in the mar- 

 ginal cells upwards of 4, per tracheid. 



Upper and lower walls of the ray cells sparingly pitted 

 in the spring wood. 



3. A. Veitchii. 



Resin cells scattering on the outer face of the summer wood. 

 Ray cells broad (tangential), oval to round. 



Pits on the lateral walls of the ray cells small, round, or 

 oval, at first obscurely bordered, but toward the summer 

 wood with a distinct border and narrow orifice. 



Pits on the lateral walls of the ray cells i -4, soon becoming 

 2, and in the summer wood i,per tracheid throughout. 

 Upper and lower walls of the ray cells thin, not 

 obviously pitted. 



Ray cells (tangential) very broad and large. 



7. A. grandis. 



Pits on the lateral walls of the ray cells 1-2, rarely 3, 

 or in the marginal cells sometimes 5, per tracheid. 

 Upper and lower walls of the ray cells thick, un- 

 equal, coarsely but very unequally pitted. 



Ray cells (tangential) chiefly oval, rarely in 

 pairs. 



6. A. amabilis. 



Pits on the lateral walls of the ray cells chiefly 2, more 

 rarely i or 4, or in the summer wood i, per tracheid 

 throughout. 



Upper and lower walls of the ray cells unequal, 

 strongly but imperfectly pitted throughout. 



Ray cells (tangential) round or oval, not very 

 large. 



5. A. magnifica. 



1. A. Fraseri, Poir. 

 Balsam. She Balsam 



Trans-verse. Growth rings rather thin, variable, the structure open through- 

 out. Summer wood very thin, of 2-6 tracheids, passing gradually 

 into the spring wood. Spring tracheids rather large and thin-walled, 



