LESSON 3.] GROWTH OF THE PLANT ?ROM THE SEED. 9 



LESSON III. 



GROWTH OF THE PLANT FROM THE SEED. Continued. 



23. So a plant consists of two parts, growing in a different 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 plantlet as it springs from the seed ; and the full-grown herb, 

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

 number. Before we trace the plantlet 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, and watch their germination. 



24. The Germinating Planllel feeds on Nourishment provided beforehand. 

 The embryo so snugly ensconced in the seed of the Maple (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 

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

 neither water nor anything else which the plantlet is imbibing from 

 the earth will answer the purpose. The proper material is nourish- 

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

 vided by the parent plant, and stored up in the seed, either in the 

 embryo itself, or around it. In the Maple, this nourishment is stored 

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

 enough of it to make the beginning of a root, and to provide for the 

 lengthening of the stemlct so as to bring up the unfolding seed-leaves 

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



S&F 2 



