SEASONING OF WOOD 283 



felled timber is drier. A variation of this belief 

 is that in summer the sap contains certain 

 chemicals which afiect the properties of the 

 wood and does not contain them in winter. 

 Again it is sometimes asserted that wood is 

 actually denser in winter than in summer, as 

 part of the wood substance is dissolved out in 

 the spring, and used for plant food, being restored 

 in the fall. 



"It is obvious that such views could apply 

 only to sapwood since it alone is in hving con- 

 dition at the time of cutting. Heartwood is 

 dead wood and has almost no function in the 

 existence of the tree other than the purely 

 mechanical one of support. Heartwood does 

 undergo changes, but they are gradual and 

 almost entirely independent of the seasons. 



" Sapwood might reasonably be expected to 

 respond to seasonal changes, and to some extent 

 it does. Just beneath the bark there is a thin 

 layer of cells which during the growing season 

 have not attained their greatest density. With 

 the exception of this one annual ring, or portion 

 of one, the density of the wood substance of the 

 sapwood is nearly the same all the year round. 

 Slight variations may occur due to impregnation 

 with sugar and starch in the winter and its 

 dissolution in the growing season. The time of 

 cutting can have no material effect on the in- 



