Modern understanding of crystal structure encourages the view that diffusion plays a large part in the transference of elements from magma to the country rock. Not only are elements presented as atoms or ions graced with much greater motility than the older conceptions of molecular aggregations permitted, but the high percentage of voids recognized in the crystalline structure allows considerable freedom of movement. The hypothesis of a residual magma enriched in elements from which the metallic ores are derived is becoming increasingly untenable. The magmatic chamber can now be visualized as a distilling apparatus from which the metals migrate upward, spreading through the country rock, taking full advantage of voids, cleavages, and fissures. Metallogenic province, then, acquires a clearer meaning.