Starting with the right-hand leaf at the bottom of Plate II, we let our eye and mind be impressed by its characteristic form, seeking to take hold of the pattern after which it is shaped. Its edge bears numerous incisions of varying depths which, however, do not disturb the roundness of the leaf as a whole. If we re-create in our imagination the 'becoming' of such a leaf, that is, its gradual growth in all directions, we receive an impression of these incisions as 'negative' forms, because, at the points where they occur, the multiplication of the cells resulting from the general growth has been retarded. We observe that this holding back follows a certain order. We now proceed to the next leaf on the same plate and observe that, whilst the initial plan is faithfully maintained, the ratio between the positive and negative forms has changed. A number of incisions, hardly yet indicated in the first leaf, have become quite conspicuous. The leaf begins to look as if it were breaking up into a number of subdivisions. In the next leaf we find this process still further advanced. The large incisions have almost reached the centre, while a number of smaller ones at the periphery have also grown deeper into the leaf. The basic plan of the total leaf is still maintained, but the negative forms have so far got the upper hand that the original roundness is no longer obvious. The last leaf shows the process in its extreme degree. As we glance back and along the whole series of development, we recognize that the form of the last leaf is already indicated in that of the first. It appears as if the form has gradually come to the fore through certain forces which have increasingly prevented the leaf from filling in the whole of its ground-plan with matter. In the last leaf the common plan is still visible in the distribution of the veins, but the fleshy part of the leaf has become restricted to narrow strips along these veins. The metamorphosis of the delphinium leaf (Plate III) is of a different character. Here the plant begins with a highly elaborate form of the leaf, while in the end nothing remains but the barest indication of it. The impression received from this series of leaves is that of a gradual withdrawal of the magnificent form, revealed in its fullness only in the first leaf. A more intense impression of what these metamorphoses actually mean is achieved by altering our mode of contemplation in the following way. After repeated and careful observation of the different forms on either of the plates, we build up inwardly, as a memory picture, the shape of the first leaf, and then transform this mental image successively into the images of the ensuing forms until we reach the final stage. The same process can also be tried retrogressively, and so repeated forward and backward.