Tendrils of the second great division consist of modified flower-peduncles. In this case likewise we have many interesting transitional states. The common vine (not to mention the Cardiospermum) gives us every possible grade from finely developed tendrils to a bunch of flower-buds, bearing the single usual lateral flower-tendril. And when the latter itself bears some flowers, as we know is not rarely the case, and yet retains the power of clasping a support, we see the primordial state of all these tendrils which have been formed by the modification of flower-peduncles. According to Mohl and others, some tendrils consist of modified branches. I have seen no such case, and, therefore, of course, know nothing of any transitional states, if such occur. But Lophospermum, at least, shows us that such a transition is possible; for its branches spontaneously revolve, and are sensitive to contact. Hence, if the leaves of some of the branches were to abort, they would be converted into true tendrils. Nor is it so improbable as may at first appear that certain branches alone should become modified, the others remaining unaltered; for with certain varieties of Phaseolus some of the branches are thin and flexible and twine, while other branches on the same plant are stiff and have no such power. If we inquire how the petiole of a leaf, or the peduncle of a flower, or a branch first becomes sensitive and acquires the power of bending toward the touched side, we get no certain answer. Nevertheless, an observation by Hofmeister well deserves attention, namely, that the shoots and leaves of all plants, while young, move after being shaken; and it is almost invariably young petioles and young tendrils, whether of modified leaves or flower-peduncles, which move on being touched; so that it would appear as if these plants had utilized and perfected a widely distributed and incipient capacity, which capacity, as far as we can see, is of no service to ordinary plants. If we further inquire how the stems, petioles, tendrils, and flower-peduncles of climbing plants first acquired their power of spontaneously revolving or, to speak more accurately, of successively bending to all points of the compass, we are again silenced, or at most can only remark, that the power of movement, both spontaneous and from various stimuli, is far more common with plants, as we shall presently see, than is generally supposed to be the case by those who have not attended to the subject. There is, however, one remarkable case of the Maurandia semperflorens, in which the young flower-peduncles spontaneously revolve in very small circles, and bend themselves, when gently rubbed, to the touched side; yet this plant certainly profits in no way by these two feebly developed powers. A rigorous examination of other young plants would probably show some slight spontaneous movement in the peduncles and petioles, as well as that sensitiveness to shaking observed by Hofmeister.