THE ANDRCECIUM. 139 



margin. So, also, if a notch is made in one of the thick veins 

 of the leaves of the splendid Gresneria, and if the leaf is placed 

 on the ground, in about a week a new plant will be pro- 

 duced on its surface. The same phenomena occur in the leaves 

 of the beautiful and scarlet-flowered Echeverias, and in many 

 other succulent plants. Now these plants could only originate 

 in the extraordinary development of certain cells in the leaf. 



In general, however, those plants which have true leaves and 

 flowers, have these cells always produced in their terminal 

 leaves, which at this time take a peculiar form, as, for instance, 

 in the stamens. These reproductive cells, which are termed 

 pollen, are always developed in the interior of these metamor- 

 phosed leaves or stamens. 



A stamen, when complete, consists of three parts ; the fila- 

 ment, or thread-like portion, / the anther, a, which is 

 situated on the top of the filament, and which usually consists 

 of two cells placed side by side, and attached to a prolongation 

 of the filament called the connectivum or connective ; and 

 the pollen, or granular matter, p, contained in the cells of the 

 anther, by means of which the ovules are impregnated, 

 (Fig. 42.) The stamens are very conspicuous in the garden 



Fig. 42. 



lily, an examination of which flower will, in connection with 

 our engraving, convey a very accurate conception of these 

 important organs* 



