FUNCTIONS OF CONIFEROUS WOOD. 



27 



water and air from the roots to the leaves, though they also 

 store up starch in autumn and winter. The pith-rays being 



Fio. 1 8. Transverse section of part of young stem of Oak, highly magnified. 

 db, pith ; c, cortex ; i, epidermis ; h, periderm ; g, collenchyma ; r, spiral 

 vessels forming protoxylem ; pv, pitted vessels (tracheae); am, secondary 

 pith-rays ; p, wood-parenchyma ; n, m, cambium ; k, bast-fibres. After 

 Hartig, from The Oak, by permission of Professor Marshall Ward, and Messrs. 

 Kegan Paul, Trench, Trtibner & Co. 



elongated radially, retaining their protoplasm, forming starch, 

 and communicating through their pitted walls with phloem and 

 even cortex as well as xylem, undoubtedly play an important 



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