3o6 



NATUR]':-STUDY 



duels. Outside of llie tu1:)ular part of tlie stem is the baric, 

 not yet hard in young tree slioots and in herbaceous plants. 



In cornstall^s, hh' stems, palm stems, and grasses, the 

 strands are not thus arranged, but arc found distributed 

 throughout the pithy substance of the stem. 



If we cut across a twig of a tree that has become woodv. 









.^M 



Fig. III. Section o[ Com Stalk Showing Fibrovascukir Bundles. 



( I'hotonijcro^fraph.) 



we shall see that the woody part is distinct from the bark 

 on the outside and a pithy portion at the centre. In the 

 spring the bark can be easily peeled from the wood. This 

 is because there is then a layer of especially thin-walled cells 

 between them which can be easily torn. In making a whistle 

 of willow or basswood, bovs beat upon the bark to crush this 

 laver of cells and thus loosen the bark. It is in this layer, 

 called the growing zone, that the new growth in the thick- 



