Exploring the Woodpile 165 



old wood toward the middle of the trunk, larger 

 roots and branches. This is completely sheathed 

 by the living part, and is of little use to the tree. 

 Heartwood has lost all power of growth, and 

 retired from active service. In it there is a large 

 proportion of mineral matter which the living 

 part of the tree is done with. Hence, when heart- 

 wood is burned it gives a larger proportion of ash 

 than does the sapwood. 



The hearts of some tropical trees furnish the 

 very close, richly-tinted woods so precious to the 

 cabinet-maker. Others contain substances which 

 the living sapwood has rejected as useless to the 

 tree, but which are useful and pleasant to humanity 

 — oils, like that which gives fragrance to sandal- 

 wood; dyes, like that in logwood; or aromatic 

 gums, like camphor. 



The heartwood of some tropical trees, indeed, 

 is so heavy and solid that it would sink in water 

 like stone. Hence the precious logs have to be 

 enclosed in cages of bamboo, that they may be 

 floated down Asian or South American rivers to 

 the coast. 



But heartwood is of little use to trees, except 

 that it gives them support. The trees which crash 

 down before gales are often found to be diseased 

 at heart, though, on the other hand, we have all 

 seen forest giants rearing their heads aloft and 

 spreading their arms abroad when their trunks 

 were mere hollow shells. 



