The Black Spruce. 



287 



I come now to speak of a remarkable peculiarity of the 

 spruce but one whose cause does not seem to be well as- 

 certained. Singular as this peculiarity is I am not aware 

 that it has ever been noticed or recorded by botanical 

 writers. It seems proper, therefore, to speak of its exist- 

 ence though we may not at present be able to give a 

 satisfactory explanation of its cause. In the vicinity of 

 Rock river, in Hamilton county, many large spruces have 

 been left standing on land cut over by lumbermen. "Why 

 were these trees left ? An examination of the trees re- 

 veals the fact that they are affected by what lumbermen 

 call seams. A chink or crack extends along the trunk 

 following the course of the grain of the wood. If the 

 grain is straight the seam also is straight, if the grain is 

 oblique the seam winds obliquely around the trunk. They 

 sometimes extend nearly the whole length of the trunk. 

 They penetrate the wood deeply, often reaching nearly to 

 the center, and they therefore detract much from the 

 value of the tree for lumber. Such trees are consequently 

 left standing when they grow far from the lumber market. 

 If the tree is cross-grained the seam renders it worth- 

 less except for fuel. Externally these seams are bordered 

 by a more or less abundant exudation of resin which in its 

 dried or hardened state is popularly known as spruce 

 gum. It is not improbable that the permanent character 

 of the seam is due to the presence of the gum which pre- 

 vents the healing of the injury. This gum is generally 

 coated by a velvety stratum of black fungoid filaments, 

 which give a blackish appearance to the seams. 



Electricity and excessive cold have been suggested as 

 possible or theoretical causes in the production of seams 

 but neither is to my mind wholly satisfactory. When 

 electricity rends the bark of a tree it carries the injury to 

 the ground, losing itself in the earth, but the spruce seams 

 generally cease before reaching the extreme base of the 

 tree. Besides, a tree struck by the electric current seldom 



