MEKISTEM. 



49 



sense of the term, vascular — the vascular tissues proper being the 

 wood and soft-bast, and possibly the cambium — these tissues being 

 functional in the conduction of sap, raw and elaborated, to and 

 from the leaves respectively. The other tissues of the stem, such as 

 cortex, young pith, &c., derive their supply of elaborated sap 

 more by osmosis through the phloem than by direct conduction. 

 The term cambium is applied, in stems and roots of Dicoty- 

 ledons and Conifers, to a narrow zone of meristem situated 

 between the woody portions of the fibro-vascular bundles and 



aid 



Fig. 32 (aemi-diagrammatie). — A Transverse Section through a First 

 Year's Stem of Pinus. — e, Epidermis; hy, hypoderrais ; s, oork- 

 layer ; c, cortex ; r, resin-canals ; end, endodermis ; ph, phloem ; 

 X, cambium layers ; ifc, interfascicular cambium ; xy, xylem ; p.xy, 

 protoxylem. 



that portion known as the phloem or bast ; it is functional in 

 producing on its inner aspect fresh elements of the wood or 

 xylem, and on the outer aspect fresh phloem elements. The 

 . origin of the cambial layer can be traced back to an early period in 

 the growth of stem or root ; a transverse section, for example, just 



4 



