Alisma Plantago. Fig, 5, Plate XII, is a reduced profile of one side of a plant gathered at random; it is seen to have five masts, of which, however, the uppermost is a mere shoot, and we can consider only their relations up to the fourth. Their lengths are measured on the line A B, which is the actual length of the lowest mast a b, A C = b c, A D = c d, and A E = d e. If the reader will take the trouble to measure these lengths and compare them he will find that, within half a line, the uppermost, A E = 57 of A D, A D = 68 of A C, and A C = 79 of A B; a most subtle diminishing proportion. From each of the joints spring three major and three minor branches, each between each; but the major branches, at any joint, are placed over the minor branches at the joint below, by the curious arrangement of the joint itself—the stem is bluntly triangular; fig. 6 shows the section of any joint. The outer darkened triangle is the section of the lower stem; the inner, left light, of the upper stem; and the three main branches spring from the ledges left by the recession. Thus the stems diminish in diameter just as they diminish in height. The main branches (falsely placed in the profile over each other to show their relations) have respectively seven, six, five, four, and three arm-bones, like the masts of the stem; these divisions being proportioned in the same subtle manner. From the joints of these it seems to be the plan of the plant that three major and three minor branches should again spring, bearing the flowers: but, in these infinitely complicated members, vegetative nature admits much variety; in the plant from which these measures were taken, the full complement appeared only at one of the secondary joints.
The leaf of this plant has five ribs on each side, as its flower generally five masts, arranged with the most exquisite grace of curve; but of lateral proportion I shall rather take illustrations from architecture;
