140 



GROWTH OF PLANTS. 



Germination of the Pea. a, the pea stript of its skin and split 

 open, to show the two cotyledons or seed-lobes, with the embryo 

 plant between them ; b, a profile view of the same parts ; c, d, e,f, 

 g, successive stages of the growth of the plant from the seed : 

 r, the seed-lobes bursting: the outer skin ; d, the root striking 

 downwards ; e, the plant about to unfold its seed-leaves, and the 

 seed-skin torn and withering ; /, the seed-leaves expanded, and 

 the root becoming fibrous ; g> the perfect plarTt. 



In the chestnut and the horse chestnut, the seed- 

 lobes are very large and thick, but do not rise above 

 ground, and send up only the gemlet, and this in time 

 becomes the trunk or stem, which I shall now describe. 



The Trunk of Plants. 



The body of a tree or shrub is always thickest at 

 the base, tapering as it rises, and composed internally 

 of what is termed wood, covered by the bark, already 

 described. The woody portion of a tree consists of 

 the following distinct parts : 



Immediately within the inner bark we find first a 



