162 COMPOUND ORGANS OP PLANTS. 



agreed to call collecting hairs. The style of these plants is at 

 first shorter than the stamens and enclosed by the cohering 

 anthers; as, it developes it pushes its way through them, and 

 the hairs on its surface brush the pollen out of the anther- 

 cells, carrying it up along with them. Hence when the 

 flowers are fully expanded we find the anthers already open 

 and in part empty, fecundation having been accomplished. 



In most cases, however, fecundation does not take place 

 whilst the perianth encloses the sexual organs, but at the time 

 of anthesis. When this period arrives, the opening of the floral 

 envelopes frees the stamens from all confinement and restraint, 

 and they take a rapid development. Their filaments elongate, 

 and the pollen contained in the anther-cells up to this period 

 succulent, moist, and adherent to the cell walls, becomes dry, 

 pulverulent, and free within their cavities. About this time 

 too, the stigma or summit of the pistil, tumefies and excretes 

 in great abundance a viscous fluid which lubricates its surface 

 and causes it to retain the pollen grains. 



But before the pollen of the stamens can be applied to the 

 stigma of the pistil, it is necessary that it should have some 

 outlet or means of escape from the anther-cells. In the 

 greatest number of cases, the cells open longitudinally through 

 the whole extent of that furrow or groove which may be 

 readily observed on their surface, as in the gilliflower, 

 Sometimes, however, the dehiscence, (dehisco, I gape), only 

 takes place at the upper part of the furrow, by an aperture 

 resembling a pore, as in Pyrola chlorantha, (Fig. 66.) 



In the common barberry, (Berberis,) the cells present no 

 furrow, but a portion of their anterior surface opens in the 

 form of valves, (Fig. 67.) In Pyxidanthera barbulata, the 



