GROWTH OF THE PLANT FROM THE SEED. [^LESSON 2 



oped, in germination ; when it had merely to unfold and grow, 

 to elongate its rudimentary stem, which takes 

 at the same time an upright position, so as to 

 bring the leaf-bearing end into the light and air, 

 where the two leaves expand ; while from the 

 opposite end, now pushed farther downwards 

 into the soil, the root begins to grow. All this 

 is true in the main of all plants that spring from 

 real seeds, although with great diversity in the 

 particulars. At least, there is hardly an excep- 

 tion to the fact, that the plantlet exists ready 

 formed in the seed, in some shape or other. 



16. The rudimentary plant let contained in 

 the seed is called an Embryo. Its little stem 

 is named the Radicle, because it was supposed 

 to be the root, when the difference between the 

 root and stem was not so well known as now. 

 It were better to name it the Caulicle (i. e. 

 little stem) ; but it is not expedient to change 

 old names. The seed-leaves it bears on its sum- 

 mit (here two in number) are technically called 

 Cotyledons. The little bud of undeveloped 

 leaves which is to be found between the co- 

 tyledons before germination in many cases (as in the Pea, Bean, 

 Fig. 17, &c.), has been named the Plumuk. 



17. In the Maple (Fig. 4), as also in the Morning-Glory (Fig. 

 28), and the like, this bud, or plumule, is not seen for some day* 

 after the seed-leaves are expanded. But soon it appears, in the 

 Maple as a pair of minute leaves (Fig. 5), erelong raised on a stalk 

 which carries them up to some distance above the cotyledons. The 

 plantlet (Fig. 6) now consists, above ground, of two pairs of leaves, 

 viz. : 1. the cotyledons or seed-leaves, borne on the summit of the 

 original stemlet (the radicle) ; and '2. a pair of ordinary leaves, 

 raised on a second joint of stem which has grown from the top 

 of the first. Later, a third pair of leaves is formed, and raisrd 

 on a third joint of stem, proceeding from the summit of the second 

 (Fig. 7), just as that did from the first; and so on, until the germi- 

 nating plantlet becomes a tree. 



FIG. .-,. Oriiiinatinn Rod Maple, which has produced its root beneath, and i developin| 

 second pair of leaves above. 6. Same, further advanced. 



