36 



THE FLOWER. 



usually spherical, but in some plants cubical, in others triangu- 

 lar, in others still, polygonal, &;c., always being of the same form 

 in the same species. (Fig. 7.) 



a. Each grain of pollen has been ascertained to consist of a membranous sack 

 containing a fluid. In this fluid are suspended molecules of inconceivable 

 minuteness, possessed of a tremulous motion. When the membrane is exposed 

 to moistm-e, it swells and bursts, discharging its contents. (Fig. 12.) 



71. Physiological structure. The filament consists of a bundle 

 of deUcate hgneous tissue, with spiral vessels, surrounded by 

 cellular tissue, the same tissues wliich compose the stem of the 

 leaf (260). The same tissues have also been traced into the 

 connectile. The anther consists almost wholly of cellular tissue, 

 corresponding to the fleshy substance (parenchyma) of the leaf. 

 The pollen consists of disintegrated 'bladders of the same tissue. 



72. Theoretical structure. Thus it is CA-ident, as we have akeady seen, that 

 however much the stamen may difi'er in aspect from a leaf, they both have the 

 same original plan. This is further evident, from the gradual transition of sta- 

 mens into petals, as seen in the water-hly or the double rose. In the former, the 

 process is so gradual that the outer whorls exactly resemble petals, except in having 

 the tops developed into yellow anthers, while in the rose we find organs in every 

 conceivable state of transition from stamens to petals. That the petals are modi- 

 fied leaves, will hereafter be more definitely shown (106). 



FIG. 8. — Stamens of the water-lily gradually passing into petals. 



73. The stamens vary in the different kinds of plants, in re- 

 spect to their number, position, relative length, connection, and 

 presence. Upon these five different conditions of the stamens, 

 the TWENTY-FOUR AUTiFiciAL CLASSES of LinusBus are founded. 



74. 1st. Number. The first eleven classes are founded upon 

 \he number of the stamens — the stamens being also /ree (63, 

 c), and of equal length. Their names arc derived from the 

 Greek numerals combined wdth av^q^^ (57, note), as follows : — 



Class I, MoNANDRiA (."oj'oj, Solitary,) includes all genera (52) 

 of plants with one stamen to each flower. 



