IS6 



General Botany 



not very heavy, and consequently is extensively used for imple- 

 ment handles, for wagons, automobile bodies, and railway-car 

 frames. The best baseball bats are made of second-growth ash, 

 because the layers of dense summer wood are thicker in more 

 rapidly growing shoots. These are but a few of many interesting 

 relations that exist between the structure and use of wood. 



Attention must also be called to the effects of the environment 

 on the woody tissue. The quality of any kind of wood is modified 

 by the conditions in which the tree lived. Oak lumber from rich, 

 well-drained, moist uplands is very different from oak that grew 

 in relatively sterile, poorly drained lowlands. Consequently, 

 lumber from certain localities is far more valuable than the same 

 kind of lumber from others. 



Annual rin^s 

 Spring wood 

 Summer wood^-^^^ 



Porea (vessels) 



Medullary rays 



Fig. qi. Diagram of a block of oak wood, magnified to show the arrangement of the various 

 tissues that produce the patterns on polished wood surfaces. 



