36 THE ANATOMY OF WOODY PLANTS 



substitute fibers, or septate fibers, are particularized by the fact 

 that the pits or pores are not of exclusively radial distribution in 

 any part of the wood, but likewise occur in numbers on the tan- 

 gential aspects of the elements. This situation in the woods of 

 later times is of special significance when considered in connection 

 with other features of structure to be noted in a later chapter. 



