traction of the membrane brings them together, to scatter their pollen in the centre of the flower. The elastic filaments of Parietaria, Engl. Bot. t. 879, for a while restrained by the calyx, as those of the lovely Kalmiæ, Curt. Mag. t. 175, 177, are by the minute pouches in the corolla, relieve themselves by an elastic spring, which in both instances serves to dash the pollen with great force upon the stigma. The same end is accomplished by the curved germen of Medicago falcata, Engl. Bot. t. 1016, releasing itself by a spring from the closed keel of the flower.
But of all flowers that of the Barberry-bush, t. 49, is most worthy the attention of a curious physiologist. In this the six stamens, spreading moderately, are sheltered under the concave tips of the petals, till some extraneous body, as the feet or trunk of an insect in search of honey, touches the inner part of each filament near the bottom. The irritability of that part is such, that the filament immediately contracts there, and consequently strikes its anther, full of pollen, against the stigma. Any other part of the
