LESSON 3.] GllOWTH OF TUE PLANT FUOM TUE SEED. 9 



LESSON III. ' 



GRC^WTH OF THR PLANT FROM TIIK SFBD. ContlTlVcd. 



23. So a plant consists of two parts, growing in a diflferent manner, 

 as well as in opposite directions. One part, the root, grows down- 

 wards into the soil: it may, therefore, be called the descending axis. 

 The other grows upwards into the light and air : it may be called 

 the ascending axis. The root grows on continuously from the ex- 

 tremity, and so does not consist of joints, nor does it bear leaves, 

 or anything of the kind. The stem grows by a succession of 

 joints, each bearing one or more leaves on its summit. Root on 

 the one hand, and stem with its foliage on the other, make up the 

 whole i)lantlet as it springs from the seed ; and the full-grown iierb, 

 shrub, or tree has nothing more in kind, — only moro in size and 

 number. Before we trace the jjlantlet into the herb or tree, some 

 other cases of the growth of the plantlet from the seed should be 

 studied, that we may observe how the same plan is worked out under 

 a variety of forms, with certain differences in the details. The mate- 

 rials for this study are always at hand. "We have only to notice what 

 takes place all around us in spring, or to plant some con.mon seeds 

 in pots, keep them warm and moist, an<l watch their germination. 



24. The Gcrininaliii2 Plaiillcl fci'ils on Noiirislinifiit proviilrrt brfon'liand. 



Tlie embryo so snugly ensconced in the seed of the 3Iaple (Fig. 2, 

 3, 4) has from the first a miniature stem, and a pair of leaves already 

 green, or which become green as soon as brought to the light. It 

 has only to form a root by which to fix itself to the ground, when it 

 becomes a perfect though diminutive vegetable, capable of providing 

 for itself. This root can be formed only out of proper material : 

 neither water nor anything else which the ])lantlet is imbibing from 

 the earth will answer the purpose. The i)roper material is nourish- 

 ing matter, or prepared food, more or less of which is always pro- 

 vided by the pan-nt plant, and stored up in the seed, either in the 

 embryo itself, or arouml it. In the ^laple, this nourishment is stored 

 up in the thickish cotyledons, or seed-leaves. And there is barely 

 enough of it. to make th«' beginning of a root, and to ])rovide for the 

 lengthening of the stemlct so as to bring up the unfolding se«-d-leaves 

 where they may expand to the light of day. But when this is done, 

 S&F— 2 



