224 



CONIFBEALES 



[CH. 



coast: the sections on which the description is based are in the 

 British Museum. Annual rings well marked, varying in breadth 

 from 1 to 3 mm. ; resin-canals are abundant both in the spring- and 







Fig. 726. Pityoxylon Sewardi. Radial section showing tracheids, tr, in a medullary 

 ray ; c, parenchyma of the ray with simple pits. (After Stopes. ) 



autumn-wood and horizontal canals occur in the lenticular medul- 

 lary rays : some of the canals are occupied by large rounded cells 

 like tyloses. The bordered pits on the radial walls of the tracheids 

 form single or double rows ; in the latter case the pits are generally 



