Geum rivale, Engl. Bot. t. 106, when cultivated in dry gravelly ground, exhibits such transformations in abundance. Between petals and stamens there is evidently more connection, as to their nature and functions, than between any other organs, and the commonly flourish and fall together. Yet only one instance is known of petals changing into stamens, which Dr. Withering has commemorated, in the Black Currant, Ribes nigrum. On the other hand, nothing is more frequent than the alteration of stamens to petals. Here then the metamorphosis begins to be retrograde, and it is still more so in the Cherry above mentioned, by which we return to the herbage again.—The line of distinction seems to be most absolute between stamens and pistils, which never change into each other; on the contrary, pistils, as we see, rather turn into petals, or even into leaves.
5. Pericarpium. The seed-vessel, extremely various in different plants, is formed of the germen enlarged. It is not
