206 



HUTCHINSON'S POPULAR BOTANY 



flower stem : the paper cylinder surrounding it will then answer to the 

 epidermis ; the eight many-threaded wicks to eight separate fibre-vascular 

 bundles ; and the wax itself will represent the ground tissue. Bear in 

 mind that the fibre-vascular bundles ("nerves" or "veins") of the leaves 

 are always in connection with the bundles of the stem, insomuch that the 

 latter are often regarded merely as lower portions of the leaf bundles ; 

 while a whole bundle formed by such union is said to be common that is r 

 common both to leaf and stem. 



If it were possible for the wicks to increase continually in thickness, 

 it is evident that they would at length meet, and form an unbroken circle 

 round the innermost portion of the wax ; and this is precisely what takes 



FIG. 258. TRANSVERSE SECTION OP A FOUR-YEAR-OLD DICOTYLEDONOUS 

 STEM (DIAGRAMMATIC). 



(m) Medulla or pith, (mr) Medullary rays, (s) Medullary sheath. (X) Xylem (wood). (P) Bast or phloem. (C Cambium. 



ring. (K) Cortex. (E) Epidermis. The eight fibro-vascular bundles (Jv) are united by wood and bast (a>6) formed by thfr 



cambium between the bundles. The figures 1, 2, 3, 4, refer to the years of growth of the wood. 



