XXXIV 
INTRODUCTION. 
10. The Seed. 
209. The Seed is the matured ovule, with the Embryo, or initial plantlet 
(15, 97), formed within it. It consists of a nucleus (174), inclosed ordi¬ 
narily by two integuments. 
210. The exterior seed-coat (the testa) is commonly much thicker 
than the inner. It varies greatly in texture and in form : it is sometimes 
expanded into a wing for facilitating dispersion by the wind, as in Catalpa 
(p. 291), and many other plants with dehiscent pods (but in no indehiscent 
fruits): and sometimes it is furnished with a tuft of long hairs or down 
(coma) to effect the same purpose, as in Willow-herb (p. 135) and Silk- 
weed (p. 366). 
211. Seeds are occasionally furnished with an extraneous covering, more 
or less complete, which does not preexist in the ovule, but is subsequently 
formed by a growth from the apex of the funiculus (174) or seed-stalk: 
this forms an Aril, of which the mace of the JXutmeg is an example, and 
also the scarlet pulpy envelope of the seeds of Celastrus (p. 83) and its 
allies. 
212. The scar left where the seed-stalk separates from the seed is the 
Hilum (177). The orifice or foramen of the ovule (174) leaves a trace 
which is named the micropyle in the seed. The Raphe of the ovule 
(177) bears the same name in the seed, where it is equally conspicuous j in 
the anatropaus form appearing as a line or ridge down the inner side of 
the seed, but in the ampkitropous only half the length, joining the hilum 
with the chalaza (178). Orthotropous and campijlotropous seeds, like the 
ovules from which they result, have no raphe, their hilum being at the 
chalaza (175, 176). 
213. The nucleus of the seed, or part contained in the integuments, 
consists either of the embryo alone (as in the almond, and all the Rose 
Family, the Pulse Family, &c.), or of this body and a mass of starch and 
other nutritive matter accumulated around it, and intended for the nourish¬ 
ment of the plantlet in germination (222). This substance, the flowery part 
of the seed, is called the Albumen, or Perisperm. Such seeds are 
termed albuminous. 
214. Seeds which are destitute of albumen (exalbuminous) have of course 
an embryo so large as to fill the whole interior ; and which is provided 
either with well-developed leaf-like cotyledons (218), as in the Maple 
(p. 80), or else with a store of nourishing matter in the thickened cotyle¬ 
dons themselves (as in the pea and bean, chestnut, &c.), on which the ger¬ 
minating plantlet feeds. 
215. The albumen is not always farinaceous , or mealy (as in Grasses, 
Buckwheat, &c.): it is often fleshy in consistence, or hard and homy or 
corneous (as in Coffee), or softer and even mucilaginous (as in Convol¬ 
vulus, p. 347), or gorged with oil (oily), as in Poppy-seeds. Although gen¬ 
erally homogeneous, yet in the nutmeg, and in the seeds of the Custard- 
Apple Family (p. 18), it is variegated or thrown into folds, or ruminated. 
216. In Water-Lilies, &c. (p. 23), the embryo is separately inclosed in 
a peculiar little sac within or at the end of the albumen. 
217. The Embryo (15, 209) varies very much in size, form, and in posi¬ 
tion with respect to the albumen when this is present. It is generally sur¬ 
rounded by and in the axis of the albumen ; but it often rests on some part 
of its surface (as wheat, and all Grass-seeds, p. 567), or is coiled like a ring 
around it (as in the Purslane Family, and many others with albuminous 
campylotropous seeds). 
218. The embryo is the essential part of the seed: to its production, 
protection, and support, all the other parts, not only of the seed, but also o 
the fruit and flower, are subservient. It becomes a plant simply by tne 
