Soon afterwards Fritz Muller discovered that the young stems of an Alisma and of a Linum-- plants which do not climb and are widely separated in the natural system-- revolved plainly, though irregularly, and he states that he has reason to suspect that this occurs with some other plants.

These slight movements appear to be of no service to the plants in question; anyhow, they are not of the least use in the way of climbing, which is the point that concerns us.

Nevertheless we can see that if the stems of these plants had been flexible, and if under the conditions to which they are exposed it had profited them to ascend to a height, then the habit of slightly and irregularly revolving might have been increased and utilised through natural selection, until they had become converted into well-developed twining species.

With respect to the sensitiveness of the foot-stalks of the leaves and flowers, and of tendrils, nearly the same remarks are applicable as in the case of the revolving movements of twining plants.