II. 1 )... INI. 



PLATE XXI. 



SUM: *- sp.w. u 



TYPICAL CROSS SECTIONS OF PINUS PALUSTRIS AND ECHINATA, AND RADIAL SECTIONS OF PINUS PALUSTRIS AND GLABRA. 



^4, PlNrs ECHINATA. Cross section of two rings; ,tp. w., springwood; su. w.. summerwood. 



H, PINUS PAI.USTRIS. Cross section of a very narrow ring. Of the two medullary rays one is cut through a row of parenchyma, the other through 



a row of tracheids. 

 C and D, PINUS GLABRA. Radial sections: m. r., medullary rays; tr., tracbeids of the medullary rays; p., parenchyma of the same; . p., simple pits 



leading from the parenchyma to the neighboring tracheids or common fibers c. tr.; b. p., bordered pit. The ray at Vis made upof tracheids 



only. 

 E, PINUS PALUSTRIS. Radial section; lettering as in D. 



Originals magnified: .-), 3{, the rest "}": illustrations: A, 'J, the rest '}. 



