1857.] Sexuality of Plants — Fecundation, Ilylridization. 341 



the stigma are covered by an epidermis, the tubular appendage is 

 applied to the surface of this epidermis and sticks to it by its ex- 

 tremity. Both then open and the granules of pollen come in con- 

 tact with the intercellular matter of the stitrma." 



These spermatic granules, adds Brongniart, penetrate into the 

 intercellular intervals of the stigma, and when they have arrived at 

 the ovule, the granules of pollen penetrate, by the opening which 

 exists in the two membranes, and then passing through a delicate 

 membranous tube, which issuing from the kernels applies itself 

 upon the placenta, and there takes up the fecundating granules to 

 convey them into the interior of the ovule. After impregnation 

 there are seen to form in it opaque granules, of a green color, which 

 at last form the embryo. Such is the theory resulting from the 

 observations of this distinguished Physiologist. This theory will be 

 found quite analogous to the same phenomenon observed in the 

 animal kingdom. Many inquiries here present themselves to the 

 mind of the curious, which can not be discussed at this time. 



Such flowers as combine the organs of the two sexes, are called 

 hermaphrodites ; those which contain but one organ unisexual. 



Polygamous plants are such as show a union of male and female 

 flowers. The term Monoecious is applied to that class of plants 

 whose stamens and pistils are in distinct flowers, both growing upon 

 the same individual ; Dioecious to those having the stamens on one 

 plant and the pistils on another. 



In the monoecious and dioecious plants, although the two sexes are 

 separated, and often placed at a distance from each other, fecunda- 

 tion is not on that account prevented from taking place. It is 

 remarkable and interesting to witness nature's adaptations and the 

 modus of doing her own work. In some flowers the sexual organs 

 at the period of fecundation acquire the property of motion, so as 

 to facilitate this operation. The stamens, for example, in certain 

 plants are seen to approach the stigma to deposit upon it their 

 pollen and then withdraw. It sometimes happens that the stamens, 

 at first naturally inclined with reference to the pistil, become sud- 

 denly straightened in such a way as to cast their pollen on the pistil 

 and afterwards assume their original position. Plants immersed in 

 water often elevate their stems, as the season of flowering advances, 

 when they at last rear their heads above the surface of the water 

 and present their opening blossoms to the sun, until impregnation 

 takes place, when the petals fade and the plant gradually sinks 



