PLATE XXVI.— TANGENTIAL SECTIONS. 

 A-C and F, PiNUS HKTEROPHYLLA. D, PlXrS KCIUNATA. E, PiN'US GLAIiUA. 



A-C, sections of mudullary rays; /c, tracheitis; p., imreuchyma; C is a "double" ray. 



In J)-F, liistological 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; 

 )•. d., transverse resin ducts; m. r., medullary rays. 

 Maguiiication of originals: A-C, ^f" ; D-F, Sf^; of illustrations : A-C, ^JU; D-F, "f. 

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