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. 
