SEEDS. 43 



the racficle (radicula, a little root), or the young root ; 

 and one or two, rarely more, imperfectly developed 

 or rudimentary leaves, the cotyledons (fcoTv\rj&<av, a 

 cup). 



These structures are closely packed in the seed, and 

 are not easily recognized at first. By keeping seeds 

 moist for a day or two until they begin to grow, or 

 germinate as the seed-growth is called, they are readily 

 detected, and may then be more easily found in the 

 dry seed. 



When somewhat advanced in growth, they are 

 familiar to every one, although they may not be re- 

 cognized by their names. In table " mustard and 

 cress," the whole consists of these organs of the two 

 plants ; the white stalk directed downwards being the 

 radicle, the two green leaf-like lobes the cotyledons, 

 and between the latter directed upwards is the very 

 minute plumule, which is more easily seen when the 

 plants have been allowed to grow larger. This struc- 

 ture of the seed is important to be known, because the 

 absence or presence and the number of cotyledons afford 

 characters, corresponding with those already men- 

 tioned in respect to the veins of the leaves and the 

 structure of the stem, for distinguishing the great 

 divisions of the Vegetable Kingdom. Thus, the Ex- 

 ogens are Dicotyledons (819, twice), their seeds having 

 two cotyledons ; while the Endogens are Monocoty- 

 ledons (ftovo9, single), having one only; and the 

 Cryptogam'ic plants are Acotyledons (a, without), 

 their seeds (spores) having none of these organs. 



Some seeds consist entirely of the embryo, sur- 

 rounded by the testa. But in many others there is 

 also present a usually whitish, firm cellular substance., 

 called the albumen (albumen, white of egg) . 



The albumen of seeds often affords good specimens 

 of secondary deposit, the cells being almost entirely 

 filled with it. An example may be found in a section 

 of vegetable ivory, of which ornaments are sometimes 



