284 



THt: FLOWER. 



fibrous lining (a little of which is shown in Fig. 45, from the anther 

 of Cobiea) is composed of simple or branching threads or bands, 

 which formed the thickening deposit on the walls of large paren- 

 chymatous cells ; all the membrane between the bands becoming ob- 

 literated as the anther approaches maturity, the latter alone remain, 

 us a set of delicate fibres. This fibrous layer gradually diminishes 

 in thickness as it approaches the line of dehiscence of the cell, 

 and there it is completely interrupted. These very elastic and hygro- 

 metric threads lengthen or contract in different ways, according 

 as the anther is dry or moist, and are thought to favor the egress 

 of the pollen. The outer stratum of the wall of the anther in dry- 

 ing contracts more than the inner, and so opens the cell, in many 

 cases turning the walls inside out after dehiscence, as in Lilies 

 and Grasses. 



529. Of all the floral organs, the anther shows least likeness to 

 a leaf. Nevertheless, the early development is nearly the same. 

 Like the leaf, the apex is earliest formed, appearing first as a solid 

 protuberance, and the anther is completed before the filament, which 

 answers to the leafstalk, makes its appearance. At first, the anther 

 is of a greenish hue, although at maturity the cells assume a differ- 

 ent color, more commonly yellow. A transverse section of the form- 

 ing anther shows four places in which the transformation of the paren- 

 chyma into pollen commences, which answer to the centre of the 

 four divisions of the parenchyma of a leaf, viz. the two sides of the 

 blade, each distinguished into its upper and its lower stratum. So 

 that the anther is primarily and typically four-celled ; 

 each lobe being divided by a portion of untransformed 

 tissue, stretching from the connective to the opposite 

 side, which corresponds to the margin of the leaf and 

 the line of dehiscence. This appearance is presented 

 by a large number of full-grown anthers : but the par- 

 tition usually disappeai-s before the anther opens, when 

 each lobe becomes single celled. The normal anther 

 is consequently considered as two-celled. In Meni- 

 spermum and Cocculus, however, the anther is strongly 

 four-lobed externally, and each lobe forms a distinct 

 473 cell at maturity. 



530. Viewed morphologically, therefore, the filament answers to 



FIO 479. IMan of a stamen as answering to a leaf ; t'.ie upper part of the anther cut away, 

 and the summit of a leaf represented above it. 



