20. ABIES NIGRA/PoiR. 



Black Spruce, Double Spruce, Bed Spruce, 



TRANSVERSE SECTION. 



RADIAL SECTION. 



TANGENTIAL SECTION. 



Schwartztanne, H, Epinette noire, >j)i Abeto negro, 



AMD SBOTIOXS XADK BT Roiurx B. Hoaoa, B. A., LCWIIXB, N. Y., U. 8. A. 



