Bulletin No. 13, Division of Forestry. 



PLATE XXVI. 



D 



r.d.~ 



r.d 



6:, 



E 



m.r: 





-m.r. 



-r.d 



F 



TANGENTIAL SECTIONS OF PINUS ECHINATA, HETEROPHYLLA, AND QLABRA, SHOWING NUMBER AND DISTRIBUTION OF 



PITH RAYS AND PROPORTION OF PITH-RAY CELLS. 



