STRUCTURE OF THE SEED. 



213 



albumen is reduced to a mere pellicle by the great development 

 of the embryo. 



The embryo is the most important part of the seed, and the 

 final product of the vegetative functions. When this is 

 formed, and the seed is fully ripe, a pause in growth takes 

 place, and the embryo which is the future plant in the first 

 stage of its development, will sometimes remain for a long time 

 in an apparently dead condition enveloped in the folds of the 

 seed, until suitable circumsrances arouse its dormant vitality. 

 The embryo is a complete plant in miniature, and therefore 

 offers the same general disposition of its parts as that which 

 we have already noticed in the adult plant. Thus we distin- 



Fig. lor. 



rig. 107. Embryo of the Pea (Pisum,) laid open to show its different parts. This 

 embryo occupies the whole interior of the seed, c, c, its two fleshy cotyledons ; p, the 

 plumule ; r, the radicle ; g, the gemmule ; /y the depression left by the gemmule in 

 the cotyledon. This embryo is dicotyledonous and bypogeal, the cotyledons remaining 

 below, during germination. 



guish, in every young plantule, an axophyte more or less 

 developed, with the usual appendages, root, stem and leaves, all 

 in a rudimentary state, and all manifesting an identity in their 

 incipient vital action with the same phenomena in the adult 

 plant. The little embryo axophyte commences to develope at 

 its two extremities in two opposite directions, and puts forth 

 laterally its rudimentary leaves ; that portion which ascends 

 is called the plumule, that which descends the radicle ; the 



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