THE SEEDLING AND YOUNG PLANT 



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* " A 



FIG. 12. Transverse section of young 1 stem,showingprimary 

 vascular bundles, &c., highly magnified, a and b, the 

 pith ; c, primary cortex ; ?', epidermis ; h, periderm (cork); 

 ff, collenchyma. Two complete primary vascular bundles, 

 and parts of two others, are shown, separated by the 

 primary medullary rays, r, spiral vessels (protoxylem) ; 

 k, bast-fibres (protophloem) ; n, ///, cambium, separating 

 the phloem from the xylem; p, wood-parenchyma. 

 Secondary medullary rays are seen in the bundles, as 

 also arc. pitted vessels of different sizes. (Th. Hartig.) 



