amorphous simply means not crystallized. Furthermore, the crystalline condition is connected with the amorphous condition by an uninterrupted series of gradations, as has been proved by the labors of Vogelsang and Lehmann. The former of these observers dissolved sulphur in sulphuret of carbon, and thickened it by mixing with it Canada balsam, the viscosity of which caused a delay in the crystallization at the will of the experimenter. By this method he substantiated a grouping of the matter into globulites, or minute isolated spheres; then into margarites, or files of spheres joined to one another. He next produced trichites, which are abundant in the obsidians—a kind of extremely fine threads of mineral, containing an internal channel, and rolling up in the most irregular fashion; microliths, under the various forms of longulites or belonites; and, finally, the crystallites and crystalline skeletons of Lehmann; and these, in their turn, led to real crystals. Each of these states presents itself as a more perfected condition than the one that precedes it, as a new appearance and complication of physical properties. Why, then, abruptly break the chain, and, having recognized the passage from the animal to the plant, and from the plant to the crystal, deny the transition, otherwise very visible, from the crystal to the amorphous body, and pretend that this is only a cadaver? Bodies sometimes crystallize under remarkably slight influences; under prolonged vibrations, as in the wire of suspension bridges; depressions of temperature, like tin; or a simple molecular action, as do arsenious acid and barley-sugar. Glasses, according to the most general opinion, are constituted of an infinite number of interlaced crystals too minute to be distinguished by our microscopes, but which may be forced to arrange themselves in groups, and thus appear visible, by means of a prolonged roasting. In science we must be on our guard against absolutely affirming what our senses do not perceive, but we must be equally wary of supposing that things possess the same limits as the instruments which we are using to-day, but which the ingenuity of an inventor may bring to a greater perfection tomorrow.
In any case, especially if we restrict individuality to the definite chemical compound, the species is more clear in mineralogy than in biology, because it is more simple. The study of the structure of minerals is comparative inorganic anatomy, and, when crystallographers measure angles, refer the infinite variety of different solids to regular geometrical types, and class them in one or another of the six categories of crystalline systems, they perform the work of anatomists. To cite their names would be to write the history of mineralogy over again. We should have to begin with Erasmus, Bartholin, Huygens, and Stenor, and end with the immense number of those who are now engaged with crystallography.
The crystal does not, then, appear suddenly any more than the plant or the animal. It passes through an embryonic state, the general
