84 BOTANY /OR BEGINNERS. [Ch. XV. 



very simple, consisting of a uniform substance enclosed in its 

 appropriate bark or skin. When the vital principle is excited 

 to action, vessels are formed, and parts developed, which seem- 

 ed not previously to have existed. The embryo is usually 

 central, and enclosed by the cotyledons ; sometimes it is no 

 more than a mere point or dot, and in some cases, altogether 

 invisible to the naked eye. The embryo Consists of two parts. 

 389. 1st. The Plume, is the ascending part, which unfolds 

 'tself into herbage. 



Fig. 65. ~ 390. 2d. The Radicle is the descend- 



ing part, which unfolds itself into roots. 

 At Fig. 65 appears the embryo in a ger- 

 minating state ; a represents the radicle, 

 b the plume, c the cord by which the plant 

 | is still connected with the cotyledons, 

 and receives from them its nourishment. 

 To use the words of an ancient bota- 

 nist, " the embryo centimes imprisoned 

 within its seed, and rem.v*is in a pro- 

 found sleep, until awakened :>y germina- 

 tion ; it meets the light and air to grow 

 into a plant, similar to its parent." 



There are various appendages which 

 may, or may not, be present without in 

 mry to the structure of the seed. 



391. Aigrette, or egret, sometimes called pappus, is a kind 

 of feathery crown with which many of the compound flowers 

 are furnished, evidently for the purpose of disseminating the 

 seed to a considerable distance by means of winds ; as the dan- 

 delion. The egret includes all that remains on the top of the 

 seed after the corolla is removed. 



392. Stipe is a thread connecting the egret with the seed. 

 The egret is said to be sessile when it has no stipe, simple 

 when it consists of a bundle of hairs without branches, plumose 

 when each hair has other little hairs arranged along its sides, 

 like the beards on a feather. 



389. Describe the pin me. 



390. Describe the radicle. 



391 What is the egret] 



392 What is the stype ? 



