Page:Popular Science Monthly Volume 23.djvu/655

Rh bits of carbonized wood, twigs, and bark, leaves no doubt as to the character of the primal vegetation.

But it is in the beds immediately associated with the coal that we find the most indubitable evidence at once of the presence and character of the former flora. Here, in strata of sand and clay, lie most beautiful impressions of the leaves of both deciduous and coniferous trees. We may say fossil leaves, but this is hardly the correct description, since we have preserved to us not a vestige of the original leaf, but simply a mold left in the imbedding clay, as the matter of the leaf disappeared. In fortunate cases, therefore, we have both the upper and lower surfaces of the leaf exhibited, and these impressions are perfect, so that experienced observers can determine, not the order only, but the genus, often the very species and variety, of the tree from which a given leaf has fallen! This seems astonishing to the



ordinary student or analyst of flowers, or to him who notes the great variety of form and feature which the leaves of a single tree present—a box-elder, for instance—but fails to see the hidden lines-which betray relationship. But such men as Goeppert, Heer, Saporta, and our own Lesquereux, like Tischendorf among the MSS., have a vision and an experience not possessed by many, a "special insight," Professor Lesquereux says, which, in presence of a single organ, a single leaf,