THE SEED. ]33 



then falls back, to be followed by the others, each in turn. The 

 flowers are usually proterandrous ; but the bee, fly, or other insect 

 visiting them receives the pollen and bears it off; whilst, after the 

 pistil ripens, other insects bring pollen from some distant flower. 



304. Fertilization has already been described (15, 20), 

 and also the embryo resulting from it (21). This subject 

 alone would fill volumes; in this elementary book we can 

 but glance at its phenomena. 



LESSON XXVI. 



THE SEED. 



305. Seed. 306. Eadicle, its direction. 307, 308. Embryo, its 

 position. 309. Size of radicle and caulicle. 310-312. Cotyledons. 

 313. Plumule. 314. Perisperm. 315. Bxalbuminous seeds. 316, 

 317. Seed-coats. 318. Micropyle. 319. Chalaza. 320. Eaphe. 321. 

 Funiculus. 322. Hilum. 323'. Seeds dissected. 



305. The Seed consists of the ovule and embryo. The 

 base of the seed is the hilum (Fig. 189) ; its apex is the 

 opposite point ; its axis is the straight or curved line be- 

 tween. The base of the embryo is the radicle ; its apex is 

 the extremity of the cotyledons ; its axis is the straight or 

 curved line between. The position of the seed in the 

 ovary (pericarp) is determined by the radicle, which 

 almost invariably points to the micropyle, and usually lies 

 close to this opening (Fig. 189, A). On account of the 

 constancy of this character, 



306. The Direction of the Radicle holds the fifth place in 

 the values (^31). It is 



/. Superior when it points to the apex of the ovary, whether the 

 ovule be orthotropous (Fig. 189, A) or anatropous (Fig. 180, E) ; 



//. Inferior when it points to the base of the ovary, as in the 

 Pretty-by-night (Fig. 189, B) ; 



III. Centripetal when it points to the central axis, as in the Lily and 

 Pea (Fig. 5, 4, e) ; 



12 



