§ 1. It may be judged, by the time which it has taken to arrive at any clear idea of the structure of shield-builders, what a task would open to us if we endeavoured to trace the more wonderful forms of the wild builders with the sword. Not that they are more complex; but they are more definite, and cannot be so easily generalized. The conditions which produce the spire of the cypress, and flaked breadth of the cedar, the rounded head of the stone pine, and perfect pyramid of the black-spruce, are far more distinct, and would require more accurate and curious diagrams to illustrate them, than the graceful, but in some degree monotonous, branching of shield-builders. In broad principle they are, however, alike. The leaves construct the sprays in the same accumulative way: the only essential difference being that in the sword-builders the leaves are all set close, and at equal intervals. Instead of admitting extended and variable spaces between them, the whole spray is one tower of leaf-roots, set in a perfect spiral. Thus, Fig. 71, at A, represents a fragment of spray of Scotch fir of its real size, B is the same piece magnified, the diamond like spaces being the points on which the leaves grew. The dotted lines show the regularity of the spiral. As the minor stems join in boughs, the scars left by the leaves are gradually effaced, and a thick, but broken and scaly bark forms instead.