76 SEED. 



the white, fleshy part of leguminous seeds, as Beans, with 

 tlir albumen of the grains, and grasses, as these parts which 

 are called cotyledons, generally rise out of the ground, and 

 sometimes become the first leaves of the new plant. It is 

 probable, however, that these seeds contain a portion of al- 

 bumen ; but this substance abounds chiefly in plants having 

 but one cotyledon. In some seeds the albumen is said to be 

 entirely wanting, as in those of the Gourd, Cucumber, and 

 Turnip. 



Fig. 144. 



The Embryo, Fig. 144. The embryo, 

 strictly speaking, consists of the cotyle- 

 dons, the radicle, and the plumula, though 

 it is often defined to include only the two 

 last named parts. The number of cotyle- 

 dons in most seeds, is two, but in the grasses, and grains, 

 there is only one, and in a few seeds, as those of the Pine, 

 there are many. In the Garden Bean, which is usually cho- 

 sen as an illustration of these parts, the two cotyledons are 

 well known under the name of the seed-lobes, being the 

 two halves of the seed which rise above the ground, and are 

 converted into the two seed leaves of the young plant. The 

 above figure is intended to represent these parts, separated 

 by the act of vegetation, or by the swelling of the radicle 

 and plumula. 



The plumula and radicle are the rudiments of the future plant. 

 The radicle e is the descending part, and ultimately forms 

 the root. The plumula a is the ascending part of the plant, 

 and is finally developed into the stem, on which the leaves 

 and fruit are formed. 



The plumula and radicle are the most essential parts of 

 all seeds, and to the perfection of these parts all the others 

 are subservient. If, when the seed is perfected, and fully 

 ripe, these parts are in any way injured, the design of nature 

 in forming the seed, and protecting it with so much care, is 

 entirely frustrated, since it will not produce the future plant. 



Plants having but one cotyledon, are called monocotyle- 

 donous, as the grains and grasses. Those having two coty- 

 ledons, are called dicotyledonous, as the Bean and Pea. 



In what plants docs the albumen chiefly abound 1 In what seeds is the 

 albumen said to be entirely wanting? What are the parts of the embryo ! 

 What is the number of cotyledons in most seeds 1 In what plants do they 

 differ from this number? What part of a bean are the cotyledons? 

 What part of the young plant is the radicle 1 What part of the young 

 plant is the piutnuia ? 



