FLOWER-LAND. 



tissues year by year, which in their turn cease to 

 grow, and form a permanent addition to the already 

 existing wood and bast bundles, as the case may be. 

 Fig. 156 C shows you the cambium .bundles very well. 



Now get a small branch of ash or elm, oak, syca- 

 more, or elder, and cut it evenly across. You can 

 easily distinguish the " pith " and the " wood," and 

 the softer part which surrounds the wood, which, I 

 dare say, you call the " bark." Peel off the bark a 

 little. How easily it comes away, and how slippery 

 the wood is where it has been taken off. It is 

 because you have pulled away the bast from the 

 wood, and the cambium cells which lie between them 

 are the growing cells, full of protoplasm, increasing 



by division, and very tender. 



So now you can 



understand some- 

 thing about the 

 growth of wood. I 

 do not know how 

 old that little branch 

 may be you have 

 been looking at, so 

 look at Fig. 157. It 

 shows you part of 

 the surface of a four- 

 year-old branch, cut 



Fig. 157. Part of a transverse section of a * 



twig of the Lime, four years old. m, the evenly across. Jiach 

 pith ; x, the wood ; I, 2, 3, 4, four f , cam Kj um 



annual rings; c t cambium; ph t bast; > C< 



A, bast fibres ; pr, k, outer bark. h as formed new 



