II0A7 PLANTS GROW YUOM THE SEKD. 



21 



into sugar, and dissolved in the water ■which is absorbed from the ground ; the coty- 

 ledon imbibes tliis, and sends it into the radicle, r, to make the root, and into the 

 plumule, p, enabling it to develop the set of leaves, 

 "wrapped up one within another, of which it consists, 

 and expand them one after another in the ah*. Fig. 

 47 shows a sprouting grain, sending down its first 

 root, and sending up the plumule still rolled together. 

 Fig. 48 is the same, more advanced, having made a 

 whole cluster of roots, and unfolded two or three 

 leaves. Nourished abundantly as it is, both by the 

 maternal stock in the grain, and by what these roots 

 and leaves obtain and prepare from the soil and the 

 air, the young corn gets a good start, is ready to avail 

 itself of the summer's heat, to complete its vegeta- 

 tion, to blossom, and to make and lay up the great 

 amount of nourishment which we gather in the crop. 

 4G. Tlie Onion. The cotyledon in Indian Corn, and 

 mo.-^t other plants which have only one, stays under 

 ground. In the Onion it comes up and makes the 

 iii'st leaf, — a slender, thread-shaped one, — and in- 

 deed it carries up the light seed on its summit. In 

 Indian Corn, all the early joints of stem remain so 

 short as not to be seen ; although later it makes long 

 joints, carrying up the upper leaves to some distance 

 from one another. In the Onion, on the conti'ary, the 

 stem never lengthens at all, but remains as a thin 

 plate, broader than it is long, with the roots springing from one side of it and the 

 sheathing bases of the leaves coverin": it on the other. 



47. Number of Cotyledons cr Seed-leaves. Indian Corn (Fig. 46) and all such 



kinds of grain-plant^, the Onion, Lilies, and the hke, have only one seed-leaf or 

 cotyledon to their embryo ; therefore they are called Moxocotyledoxous Plaxts, 

 and the embryo is called monocotyledonous^ — a long word, meaning " with one 

 cotyledon." 



48. The embryo of the Morning-Glory (Fig. 19), of the Maple (Fig. 27), 

 Bean (Fig. 32-34), Almond, Peacli, and Cherry (Fig. 36-38), Oak (Fig. 40),. 



