1311. The direction of the seeds is possible in five ways, either upright and horizontal, transverse, or rising obliquely upwards and downwards in relation to the axis of the ovary. 1312. Every perfect seed (of Dicotyledons) is none other than a pentifoliar, involuted, pinnate leaf. The shell of the seed is the leaf-spathe or _phyllodium_, the two seed-lobes are the two posterior pinnate leaflets, while the germinal leaflets, or _plumula_, are the two anterior pinnate leaflets, together with the odd leaflet. The seed-rib or vascular cord (_raphe_) is continued into the seed-rootlet or radicle, and this into the petiole of the cotyledons. 1313. Every seed-coat must consist of three integuments; for every leaf consists of the lower and upper membrane, and of the interjacent parenchyma, in which the vessels are dispersed. The external leaf-membrane forms the most hard and coloured covering of the seed (_testa_), the internal the brown seed-tunic or _pellicula_; between the two lies the brown fibrous tissue, or desiccated parenchyma with the vessels. 1314. The hilum is the basis of the bud or of the seed-leaf; the seed-hole or micropyle is on the apex of the involuted bud, or rather of the phyllodium, in which the germ lies rolled up. 1315. Umbilicus and micropyle are united with each other by means of seed or leaf-rib (raphe). Both rarely stand opposite to each other, so as that the one should be below, the other above; but the apex of the leaf is usually so involuted that it again reaches the bottom of the leaf, whereby umbilicus and micropyle come into close and mutual approximation, as in the beans. The seed-petiole elongates itself into the seed-rib; this is continued upon the back of the phyllodium or testa, bends round, and returns again to the umbilicus, so as to describe a complete circle. The shell of the seed has consequently the form of the young fern or fern-capsule. 1316. The radicle is the continuation of the seed-rib, which is, however, dismembered itself, moves off, and thereby causes the micropyle to be, or, properly speaking, only renders it, free. The testa or seed-shell is consequently a phyllodium thrown over the germ, but the micropyle is the upper opening of the bud. 1317. The germ of the seed or embryo, namely, radicle, cotyledons and plumule, is therefore only the quinary pinnate leaf without the spathe or testa.