11. lii ic. 181. 



PLATE XXV. 



D 



r.d.- 



r.d 



m.r: 



m.r: 



,-tr. 



A 



B 



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



PITH RAYS AND PROPORTION OF PITH-RAY CELLS. 



A-C and F, PlNl'H HETEROPHYLLA. D, PlNUS ECHINATA. E, P:NUS GLABRA. 



A-C, Sections of medullary rays; tr., traeheids; p., parenchyma; C is a " double " ray . 



In D-F, hlntologica] details are omitted; they are camera drawings showing number and distribution of medullary rays, and also 



the proportion of the tracheids to parenchyma in each ray, the former being indicated by dots; r. d., transverse resin 



ducts; w. r., medullary rays. 

 Magnification of originals: A-C, }; D-F, >f; of illustrations: A-C, 3 } 2 ; D-F. f. 



