INTRODUCTORY CHAPTER. 5 



consists of a thicker and paler membrane than the first, named endocarp {endocar- 

 dium). The intermediate portion consists of a mOre or less succulent tissue (accord- 

 ing to the proportions of fibre and parenchyma), named mesocarp (mesocarpium). 

 In the solitary carpel which forms the pistil of a Cherry (fig. 16), Peach, or Apricot 

 (fig. 15), the epicarp (f) is a thin skin, the mesocarp (figs. 16, me, and 15, b) is very 

 thick and succulent when ripe, and the very hard endocarp (figs. 10, n, and 15, d) 

 forms the stone. 



The fibro-vascular bundles (fig. 14, l) which are found on the edges of the blade 

 of the carpellary leaf, and which both bear the ovules (o) and transmit nourishment 

 to them, are called the placentce (placentae, tropliospermia). Each placenta produces 

 lateral branches or cords, called funicles {funiculi, p), which are sometimes very 

 short, and through which the nourishing juices are conveyed to the seeds. When 

 the funicles are absent (fig. 13), nourishment is transmitted directly to the seed 

 from the placenta. 



The seed or plant-egg (semen, fig. 17) is the ovule fertilized by the pollen. It is 

 composed, (1) of a very small body, destined to reproduce the plant, the embryo 

 (or plantula] ; (2) of an envelope or integument surrounding and protecting the 

 embryo. This integument (in the ovule) either originates from the top of the 

 funicle (fig. 17, f), or directly from the placenta (fig. 13). It u-sually consists of two 

 layers or coats, an external testa (fig. 17, i), and an internal endopleura (e). The 

 point of union of the seed and funicle, and at which its nourishment enters, is called 

 the hilum or umbilicus (fig. 18, h), and is a part of the testa. The chalaza (fig. 

 17, h) marks the spot where the juices penetrate the internal coat and reach the 



T R M 



IG. Cherry. 

 Eipe carpel, cut vertically, 

 showing the seed suspetiQcd 

 by a funicle c springing 

 from the bottom of the 

 kernel. 



18. Pea. 

 Part of the in- 

 17. Pea. Seed deprived oi half its tegument of the 



integument (mag.). seed (mag.), 19. Pea. Embryo spread open (mag.). 



embryo, and is usually indicated on the outside by a projection or thickening or 

 discoloration. When the hilum and chalaza are superimposed, the juices reach the 

 embryo directly ; when they are at opposite ends, they are connected by a small cord, 

 raphe (figs. 17, A, and 18, e), which runs between the two coats. The small opening 

 through which the ovule is acted on by the pollen is the micropyle (figs. 17, and 18, m). 

 The embryo (figs. 17, 19) is a complete plant in miniature, composed of a stem, 

 cauUcle {tigellus, caulieulus, T),-a root, radicle {radicula, r), one or two leaves, coty- 

 ledons {cotyledones, c), and a bud, plumule {gemmula, plumula, g), usually occupying 

 a small pit (p) sunk in the thickness of the cotyledons. The young plant, after 

 having been nourished by the juices transmitted through the funicle, detaches 



