30 



OF WOOD IN GENERAL. 



Maples ; or nearly circular. In the last-mentioned case the pro- 

 jections of the primary xylem into the pith may give the pith a 



wavy or crenate outer margin, as in Hawthorn, Rowan, Laburnum, 

 Horse Chestnut, or Elder or this margin may appear even, as in 

 Elm, Hazel, and Dogwood (Cornus). In the Walnut the pith has 



