BOTANY. 101 



THE SEED. 



The seed contains the rudiments of a new plant, and is the 

 final product of all the complicated and beautiful processes of 

 vegetation. The essential parts of the seed are, the integu- 

 ment a, the albumen and the embryo. 



The integuments are composed of several distinct layers, 

 which constitute the immediate coverings of the other parts. 



The albumen lies next to the integuments, constituting the 

 principal bulk of some seeds ; it is a whitish substance, com- 

 posed mainly of starch, which, by the chemical changes which 

 it undergoes during the process of germination, serves to 

 nourish the embryo plant. 



The embryo comprises all the rudiments of the new plant: 

 it consists of three parts, viz : the radicle, the plumule, and the 

 cotyledon. 



The radicle is the part which forms the root, the plumule 

 Fig. 10. forms the ascending portion of the plant, 



the cotyledon is the bulky part of seeds, and 

 forms the first leaves of young plants, which 

 lin the garden bean, cucumber, &c., are 

 I thick, fleshy and oval, when they first rise 

 above the surface of the ground: these 

 ! support the plant and perform the function 

 of leaves until the proper leaves are formed. 



[This figure shows an embryo with its plumule 

 and radicle developed from the cotyledon: a, radi- 

 cle; b, plumule; c, cotyledon.] 



GERMINATION OF SEEDS. 



Germination consists of the first chemical changes and vital 

 action, which take place when a new plant is about to be 

 produced. 



" When the seed is planted in a moist soil, at a moderate 

 temperature, the integuments gradually absorb water, soften 



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