72 PRACTICAL BOTANY. 



carp and its inversions, are the same as tliose used to desig- 

 nate the same conditions in the ovule — namely, erect, 

 ascending, orthotropous, etc. The seed is sometimes par- 

 tially or wholly enclosed by a fleshy or pulpy enlarge- 

 ment of the seed-stalk or funiculus ; and such enlargement 

 we call aril, as the scarlet covering of the seed of Staff- 

 tree. 



The Keenel enclosed in the seed-coat may consist of two 

 parts, the embryo and the albumen, or of the embryo 

 alone. The albumen has also been called perisp&rm or 

 endosperm. Seeds with albumen are said to be albuminous 

 (see Cut XIY., 1, 2), those without it exalbumdnous 

 (Fig. 3). "When albumenis present, its quantity varies (see 

 Figs. 1, 2). The dicotyledonous embryo has the plumule 

 between two opposite minute leaves, or cotyledons — see 

 Fig. 4: (an embryo with two cotyledons occurs in all 

 Exogens, except the Gymnosperms, in which the embryo 

 has 3-15 cotyledons). The monocotyledonous embryo, on 

 the other hand, has only one cotyledon, and does not 

 usually presejnt a manifest radicle or plumule, but often 

 consists merely of an undivided, club-shaped body, at least 

 before germination. In Triglochin (an Endogen), we de- 

 tect a vertical slit just above the radicular end of the em- 

 bryo, through which the plumule protrudes in germina- 

 tion (Fig. 5). A horizontal section at this point reveals 

 the plumule, enwrapped in the cotyledon (Fig. 6). The 

 plumule is also conspicuous, tinder a lens, in grasses. 

 Figures all magnified, the first three representing vertical 

 sections of seeds, the other three embryos, the last in part : 

 1, seed of Delphinium, the minute embryo (e) at the base 

 in abundant albumen (a) ; 2, seed of Violet, with the em- 

 bryo in the axis of the albumen ; 3, seed of Elodea, with 

 the embryo, but no albumen ; 4, embryo of the Bean ; 5, 



