It may be added, as it will serve to sum up the foregoing views on the origin of tendril-bearing plants, that if these views be correct, L. nissolia must be descended from a primordial spirally twining plant; that this became a leaf-climber; that first part of the leaf and then the whole leaf became converted into a tendril, with the stipules by compensation greatly increased in size; that this tendril lost its branches and became simple, then lost its revolving power (in which state it would resemble the tendril of the existing L. aphaca), and afterward losing its prehensile power and becoming foliaceous would no longer be called a tendril. In this last stage (that of the existing L. nissolia) the former tendril would reassume its original function as a leaf, and its lately largely developed stipules, being no longer wanted, would decrease in size. If it be true that species become modified in the course of ages, we may conclude that L. nissolia is the result of a long series of changes, in some degree like those just traced. The most interesting point in the natural history of climbing plants is their diverse power of movement; and this led one on to their study. The most different organs--the stem, flower-peduncle, petiole, midribs of the leaf or leaflets, and apparently aerial roots--all possess this power. In the first place, the tendrils place themselves in the proper position for action, standing, for instance, in the Cobæa, vertically upward, with their branches divergent and their hooks turned outward, and with the young terminal shoot thrown on one side; or, as in Clematis, the young leaves temporarily curve themselves downward, so as to serve as grapnels. Secondly, if the young shoot of a twining plant, or of a tendril, be placed in an inclined position, it soon bends upward, though completely secluded from the light. The guiding stimulus to this movement is no doubt the attraction of gravity, as Andrew Knight showed to be the case with germinating plants. If a succulent shoot of almost any plant be placed in an inclined position in a glass of water in the dark, the extremity will, in a few hours, bend upward; and if the position of the shoot be then reversed, the now downward bent shoot will reverse its curvature; but if the stolon of a strawberry, which has no tendency to grow upward, be thus treated, it will curve downward in the direction of, instead of in opposition to, the force of gravity. As with the strawberry, so it is generally with the twining shoots of the Hibbertia dentata, which climbs laterally from bush to bush; for these shoots, when bent downward, show little and sometimes no tendency to curve upward.