THE VEGETABLE CjELL. 131 



ovary may grow up into a fruit, and the ovule into a seed nor- 

 mally formed on the exterior, without this, but the latter is in- 

 capable of germination, because it contains no embryo. In the 

 naked-seeded Phanerogamia (the Cycadese and Coniferse), the 

 pollen falls upon the freely-exposed ovule, and impregnates it 

 immediately; in the rest of the Phanerogamia, in which the 

 ovules are enclosed in an ovary, the impregnation is effected 

 through the medium of the pistU, with the stigma of which the 

 pollen must come in contact. 



In the majority of plants, the ovary is not perfectly closed 

 above, its cavity being prolonged upward into a very narrow canal, 

 which runs through the substance of the style ; or if the borders 

 of the carpellary leaf where this forms the style, are not blended 

 together, it has the form of a groove running on the inside of the 

 style. The cellular tissue which forms the wall of this canal, is 

 distinguished from the rest of the tissue of the style by softness 

 and transparency, and frequently also by the absence of colour. At 

 the epoch of the perfect development of the pistil, there exudes 

 among its cells (which are usually much elongated, but may also 

 be roundish) a mucilaginous fluid, which so loosens the connection 

 of the cells, that they may be readily separated, ^and through the 

 expansion caused by the excreted fluid, they frequently quite close 

 up the canal of the style. This cellular tissue, which, after 

 Ad. Brongniart, is called the conductiTig tissue, appears at the 

 upper orifice of the canal, where it is frequently enlarged into a 

 large globular or lobulated body, free to the external air, and this 

 constitutes the stigma. The cells forming the stigma are ordi- 

 narily less elongated than those lying in the interior of the style, 

 and are often more firmly blended together. The outermost layer 

 of them does not form a continuous, smooth epidermis, but its 

 cells are usually in the form of papillae of variable length ; and 

 papillae of this kind present themselves along the whole of the 

 canal of the style, upon the surface of the conducting tissue. At 

 the opposite extremity of the canal, the conducting tissue stretches 

 into the cavity of the ovary, and here, in general, runs on its wall 

 to the points of insertion of the ovules, where it appears in very 

 diflerent forms, varying according to the structui'e of the ovary, 

 the number and position of the ovules, &c. ; sometimes covering 

 the many-ovuled placenta as a broad layer ; sometimes running, 

 in the form of a narrow strip, to a single ovule ; sometimes pro- 

 jecting, in a conical shape, into the <^vity of the ovary, and 

 coming into direct contact with the micropyle of an ovule, &jc. 

 The conducting tissue is by no means to be regarded as a special 

 organ, but consists of a modification of the tissue of the carpellary 

 leaf, occurring at particular parts,— usually of its upper surface, 

 where this forms the canal of the style. In other cases, however, 

 this modification of the tissue may go out through the substance 

 of the carpellary leaf to its posterior surface^ as in the Asclepiadeje, 



