PLATE XXIII— RADIAL SECTIONS. 



J and S, PiNUS ECHINATA. m. )•., medullary rays; j)., parenchyma of same; fc, tiansverse traclieids of rays 



simple pits; h. p., bordered pits; c. tr., common tracheids. 

 C, PiNUS IIETEROPHYLLA. »H. ]('., summcrwood; other letters as in A. 

 Originals magnified ^f?; illustrationB, *{". 

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