129 



The walls of the tracheides bow apart to such an extent as to appear 

 like a string of beads in the longitudinal sections. 



In distinguishing the woods of the two trees the factors which are 

 most prominent and also most readily obtained are in Pinus taeda, the 

 junction of the spring and summer wood, in the year's zone, not distinct, 

 the medullary rays somewhat obscure, and close together ; in Pinus palus- 

 tris spring and summer wood distinct from each other, the medullary rays 

 conspicuous and farther apart, having a ratio of 4 to 11 to those in Pinus 

 taeda. The other differences noted might be used in verification, but are 

 not essential in the differentiation of the two woods. 



