I50 



PLANT ORGANS OR PARTS OF PLANTS. 



surrounded by a layer of pitted woody parenchyma 

 containing resin at times. Pitted vessels predominate. 

 The woody fibres are numerous, making up the greater 

 part of the bundle. The woody parenchyma forms 

 tangential bands which are quite a marked feature of this 

 wood. These contain at times calcium oxalate crystals. 

 The pith consists of large, spherical cells, abundantly 

 pored, containing numerous calcium oxalate crystals. 



w- PU'S' 



Fig. 38. — Cross-section Quassia. 

 WP, Wood parenchyma; M, Medullary rays; W, wood fibres; RD, re- 

 ticulated ducts. 



Surinam. — All the elements are smaller, so that the 

 wood seems harder and thicker. The medullary rays 

 are narrower, generally only one, rarely two cells wide, 

 five to twenty cells high; woody parenchyma less; 

 vessels thicker walled. Vessels in groups of two to five; 

 about one-half diameter of distance between medullary 

 rays; pores broader than long. Calcium oxalate not 

 found in wood, but in medullary rays. 



Under the low power the stem and branch pieces 



