12 



A PATTERN PLAKT. 



[section 2, 



11. On committing these seeds to moist and warm soil tbej soon sprout, 

 1. e. germinate. The very short stem-part of the embryo is the first to 

 grow. It lengthens, protrudes its root-end ; this turns downward, if not 

 already pointing in that direction, and while it is lengthening a root forms 

 at its point and grows downward into the ground. This' root continues to 

 grow on from its lower end, and thus insinuates itself and 

 penetrates into the soil. The stem meanwhile is addmg 

 to its length throughout ; it erects itself, and, seeking the 

 light, brings the seed up out of the ground. The mate- 

 rials for this growth have been supplied by the cotyledons 

 or seed-leaves, still in the seed : it was the store of nour- 

 ishing material they held which gave them their thickish 

 shape, so uulike that of ordinary leaves. Now, relieved of 

 a part of this store of food, which has formed the growth by 

 which they have been raised into the air 

 and light, they appropriate the remain- 

 der to their own growth. In enlarging 

 they open and throw oif the seed-husk ; 

 they expand, diverge into a horizontal 

 position, turn green, and thus become 

 a pair of evident leaves, the first foHage 

 of a tiny plant. This seedling, although 

 diminutive and most simple, possesses 

 and puts into use, all the Obgans of 

 VEGBTA.TION, namely, root, stem, and 

 leaves, each in its proper element, — the 

 root in the soil, the stem rising out of 

 it, the leaves in the light and open air 

 It now draws in moisture and some 

 food-materials from the soil by its root, 



conveys this through the stem into the leaves, where these materials, along 

 'with other crude food which these imbibe from the air, are assimilated into 

 vegetable uiatter, i. e. into the material for further growth. 



12. Further Growth soon proceeds to the formation of new parts, — 

 downward in the production of more root, or of branches of the main root, 

 upward in the development of more stem and leaves. That from which a 

 stem with its leaves is continued, or a new stem (i. e. branch) originated, is 

 a Bub. The most conspicuous and familiar buds are those of most shrubs 

 and trees, bearing buds formed in summer or autumn, to grow the followiug 



Fig. 5. Early Flax seedling ; stem (caulicle), root at lower end, expanded seed- 

 leaves (cotyledons) at the other : minute bud (plumule) between these. 6. Same 

 later; the bud developed into second pair of leaves, with hardly any stem-part be- 

 low them; then into a third pair of leave.s, raised on a short .ioint of stem ; and a 

 fifth leaf also showing. 7. Same still older, with more leaves developed, but these 

 singly (one after another), and with joints of stem between them. 



