Free The Lying Stones of Marrakech by Stephen Jay Gould Page A

his fossil wood had arisen by transformation of earths and clays into forms resembling plants. His “wood” had therefore been generated from the mineral kingdom, proving that fossils could form inorganically. Cesi then claimed that his fossils stood midway between the mineral and vegetable kingdoms, providing a smooth bridge along a pure continuum. Nature must therefore be constructed as a chain of being. (Cesi had strongly advocated this position for a long time, so he can scarcely be regarded as a dispassionate or disinterested observer of fossils. His botanical classification, eventually published by Stelluti in 1651, arranged plants in a rising series from those he interpreted as most like minerals to forms that he viewed as most like animals.) Since Cesi could not classify his fossils into any conventional kingdom, he awarded them a separate name for a novel realm between minerals and plants—the Metallophytes.
    Stelluti, playing his usual game of follow the leader, devoted his 1637 treatise to supporting Cesi’s arguments for the transitional status of metallophytes and their origin from the mineral kingdom as transmuted earths and clays. The fossils may look like plants, but they originate from heated earths of the surrounding countryside (where subterranean magmas boil the local waters, thus abetting the conversion of loose earth to solid metallophyte). Stelluti concludes:
    The generation of this wood does not proceed from the seed or root of any plant, but only from a kind of earth, very much like clay, which little by little becomes transmuted to wood. Nature operates in such a manner until all this earth is converted into that kind of wood. And I believe that this occurs with the aid of heat from subterranean fires, which are found in this region.
    To support this conclusion, Stelluti presented the following five basic arguments:
    1. The fossil wood, generated from earth, only assumes the forms of tree trunks, never any other parts of true plants:
    It is clear that this wood is not born from seeds, roots or branches, like other plants, because we never find pieces of this wood with roots, or branches, or nerves [internal channels for fluids], as in other [truly vegetable] wood and trees, but only simple trunks of varied form.

    Three figures of fossil wood from Stelluti’s treatise of 1637 .
    2. The fossil trunks are not rounded, as in true trees, but rather compressed to oval shapes, because they grow in situ from earths flattened by the weight of overlying sediments (see the accompanying reproduction of Stelluti’s figure):
    I believe that they adopt this oval shape because they must form under a great mass of earth, and cannot grow against the overlying weight to achieve the circular, or rather cylindrical, form assumed by the trunks of true trees. Thus, I can securely affirm that the original material of this wood must have been earth of a clayey composition.
    3. Five of Stelluti’s plates present detailed drawings of growth lines in the fossil wood (probably done, in part, with the aid of a microscope). Stelluti’s argument for these inner details of structure follows his claim for the outward form of entire specimens: the growth lines form wandering patterns reflecting irregular pathways of generation from earth, following limits imposed by the weight of overlying sediments. These lines never form in regular concentric circles, as in true trees. Stelluti therefore calls them onde , or “waves,” rather than growth lines:
    The waves and veins are not continuous, all following the same form, as in [vegetable] wood, but are shaped in a variety of ways—some long and straight, others constricted, others thick, others contorted, others meandering…. This mineral wood takes its shape from the press of the surrounding earth, and thus it has waves of such varied form.
    4. In the argument that he regarded as most decisive, Stelluti held that many specimens can be found