270 



ORGANOGRAPHY. 



Fig. 576. 



Fig. 577. 



Fig. 575. Young flower-bud of the Flowering Rush {Butomm umbellatus). 

 The carpels, car, are still concave on the inside and resemble small leaves. 

 Fig. 576. The carpels in a more advanced state, but the folded edges still 

 separated by a slit. Fig. 577. The same carpels in a perfect condition. 



thus form a hollow portion or ovarj, in which the o^'ules soon 

 make their appearance (fig. 577). This gradual transition of 

 Fiq. 578. ^itle leafy organs into carpels may be well seen 

 in the Flowering Rush (Butovms umbellatus). 

 We have thus in the first place shown, that 

 carpels become changed into leaves by cultiva- 

 tion, and secondly, that they make their first 

 appearance in the form of little organs re- 

 sembling leaves ; and in both ways, therefore, 

 we have proofs afforded us of their leaf- like 

 nature. 



Structure of the Carpel. — The ovary being 

 the homologue of the lamina of the leaf, it 

 presents, as might have been expected, an 

 analogous structure. Thus it consists of pa- 

 renchyma, which is often much developed, and 

 through which vascular bundles composed of 

 spiral and other vessels ramify, and converge 

 towards the base of the style, or terminate at 

 the upper part of the ovary when that is absent. 

 The whole is covered externally by a layer of 

 epidermis (fig, 578, ep). The parenchyma is 

 usually of a more lax nature as we proceed 

 towards the inside of the ovary, where it forms 

 a very delicate lining, called epithelium, and 

 which has been already described as a modified 

 form of epidermis. This epithelium corre- 

 sponds to the epidennis of the upi)er surface of 

 the leaf, and being develo]»ed under the absence 

 of liglit, it has usually a jtale colour, and is 

 devoid of stoniata. The e])idermis on the out- 

 side of the ovary con-esjjonds to that of the lower surface of 

 the leaf, and like it is frequently clothed with stomata, and 



Fig. 578. Vertical 

 section of the pis- 

 til of the Apricot 

 (I'rumis ArviC- 

 nuica). ov. Ovule, 

 which is enclosed 

 in an ovary; cp. 

 Epidermis, form- 

 ing the external 

 coat of the ovary; 

 mc. Middle layer; 

 end. Inner coat; 

 tc. Style with a 

 canal in its cen- 

 tre ; St. Stigma. 



