II. Doc. 181. 



PLATE XXIII. 



r mr. 





Ir. 



'b.p. <c 



Fie-4 



RADIAL SECTIONS OF PINUS T/CDA AND TANGENTIAL SECTIONS OF PINUS PALUSTRIS AND ECHINATA. 



A and B, PINUS T<EDA. Radial sections; m. ?., medullary rays; tr.. tracheids: p . parenchyma of the rays: . p., simple pit: 6. p., bordered pit; c. tr,, 



common tracheids. 

 C-K, tangential sections. 



C", PINUS PALUSTRIS. Left-hand part in springwood, right-hand portion in summerwood. 

 D-E, PINUS ECHIXATA. D, section in springwood; a-e, medullary rays; a, a small ray co-noosed of tracheids only c. a "triple" ray; d, bordered pit 



showing the membrane in place. E. section in summerwood; a, bordered pit, other letters as in A and B. 

 Magnification of originals, s }; of illustrations: A and B, 2 J; C-E, a } 



