PLATE XXII. 



A, PiNUS ECHINATA. Cross Section of two rings; sp. ii\, spritigwood; »». w., snmnii'iwood. 



Ji, Pints palustris. Cross section of a very narrow ring. Ot'tlie two medullary rays one is cut tlirougli a row of 



parenchyma, the other through a row of tracheids. 

 C au,d D, PINU.S GLABRA. Kadial sectious ; m.r., medullary rays; ir., tracheids of the medullary rays; j).,pareuchynia 



of the same; 8. j)., simple pits leading from the parenchyma to the neighboring tracheids or common fibers 



c. tr ; b. p., bordered pit. The ray at C is made up of tracheids only. 

 E, PiNUS TALl'STRis. Radial section; lettering as in D. 



Originals magnified : -J, ^J"!, the rest ^?" ; illustrations: -J, ^f"; the rest ^'(o. 

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