FRUIT OR MATURE PISTIL. 



251 



wall of the ovary after fertilization. In Tribulus terrestris, each cell of 

 the ovary (fig. 438) has slight projections, c, on its walls, interposed 

 between the ovules, o, which, when the fruit is 

 ripe, are seen to have formed distinct transverse 

 divisions (fig. 439 c), or spurious dissepiments, 

 separating the seeds, g. In Astragalus, the 

 folding of the dorsal suture inwards converts a 

 one-celled ovary into a two-celled fruit. 



523. The development of cellular or pulpy 

 matter frequently makes great changes in the 

 fruit, and renders it difficult to discover its for- 

 mation. In the Strawberry, the axis becomes succulent, and bears 

 the carpels on its convex surface; in the Rose, there is a fleshy lining 

 of the calyx (sometimes called a disk), which bears the carpels on its 

 concave surface. In the Gooseberry, Grape, Guava, Tomato, and 

 Pomegranate, the seeds nestle in pulp formed apparently by the 

 placentas. In the Orange, the pulpy matter surrounding the seeds is 

 formed by succulent cells, which are produced from the inner lining 

 of the pericarp. 



524. The pistil, in its simplest state, consists of a carpel or folded 

 leaf, with ovules at its margin; and the same thing will be found in the 

 fruit, where the pericarp, as in the Bean (fig. 440), 



represents the carpellary leaf, and the seeds corre- 

 spond to the ovules. The pericarp consists usually 

 of three layers: the external (fig. 440 e), or epicarp 

 (tTTi, upon, or on the outside, xajTro?, fruit), cor- * ' 

 responding to the lower epidermis of the leaf; the 

 middle (fig. 440 TO), or mesocarp (f^saof, middle), 

 representing the parenchyma of the leaf; and the 

 internal (fig. 440 ), or eridocarp (ivlw, within), 

 equivalent to the upper epidermis of the leaf, or 

 the epithelium of the ovary. In some plants, as 

 Colutea arborescens, the pericarp retains its leaf- 

 like appearance, but in most cases it becomes al- 

 tered both in consistence and in colour. Sometimes the three parts 

 become blended together, as in the Nut ; at other times, as in the 

 Peach, they remain separable. In the latter fruit, the epicarp is thick- 

 ened by the addition of cells, and can be taken off in the form of what 

 is called the skin; the mesocarp becomes much developed, forming the 



Fig. 438. Cell or loculament of the ovary of Tribulus terrestris, out vertically, to show the 

 commencement of the projections, c, from the paries, which are interposed between the ovules, o. 



Fig. 439. The same in a mature state, showing the transverse partitions, c, dividing the fruit 

 into cavities, in one of which a seed, g, is left. 



Fig. 440. Lower portion of the carpel or legume of the Bean, Faba sativa, cut transversely, to 

 show the structure of the pericarp, e, Epicarp, or external epidermis, m, Mesocarp. n, Endo- 

 carp. s d, Dorsal suture, s v, Ventral suture, g, A seed situated at the upper part of the sec- 

 tion, and cut also transversely. 



e -- 



7H-- 



n 



