12 



ACADEMIC BOTANY. 



stage of growth, as in the Yellow Water-Lily (Fig. 7, E) ; 

 it retains its special secretion or food, whilst other food is 

 developed in the nucleus outside of it. This outer nutri- 

 ment is the perisperm ; the inner nutriment is called Endo- 

 sperm, a term sometimes (but loosely) applied to the true 

 perisperm. The persistent embryo-sac here is called a Vi- 

 teUus (L. yolk of an egg) because in position it resembles 

 the yolk of an egg.] In many cases the embryo itself 

 becomes large, completely fills the seed, and stores up the 

 nutriment in its own proper organs, as in the Pea, Acacia 

 (Fig. 7, A, B), Walnut, Almond, etc. 

 22. Fruit. Seed.— Whilst this pro- 

 cess is going on in the embryo itself, 

 the seedrcoats grow; the outer coat 

 thickens ; in Gymnosperms (which we 

 know have no ovary) this outer coat 

 becomes fleshy or woody, simulating 

 a true seed-cover. In Angiosperms 

 (which have an ovary) 

 the ovary grows and be- il 

 comes a Pericarp (Gr. 

 peri, around, Icarpos, 

 fruit). In the Pea and 

 Bean (Fig. 5, e) the 

 pericarp is a pod with 

 many seeds. In the 

 Cherry the pericarp is a 

 stone with a 

 fleshy exterior. 

 Let us remem- 

 ber, in the bcr 

 ginning of our 



Lessons that ^^^' '^•~^i embryo uf Pea (/"iw/m), with the two cotyledons cc 



' , separated to show the plumule y, and radicle r. B, seed of Silk- 



th& Seed itself flower (.4 i6T«iajKM6rMfliH) sprouting; top of cotyledons stillen- 



,7 . closed in the seed-Coats. 0, same, further advanced. Both these 



IS tfie true figures sliow the coHum, or neck, m. D, young Maple (.^cer) ; r, 



TTfii^f • Q 1 1 ^**l^cle; m, colhim ; /, caulicle; cc, cotyledons ; f/, plumule; cau- 



J? t Uiiv , dll ijj^ gj. ,j.m5 stem, uot yet developed. E, seed of Yellow Water- 



Other "Darts of ^ ^^ {Nuphar), showing the vitellus with its endosperm, and the 



_-t^ * outer iierisperm ; i-mhrvo minute. 



the 110 wer — 



ovary, calyx, etc. — are but its envelopes, whether they be 



edible or not ; though these too are called the fruit. 



