The difficulty in considering crystals as "living things" is partially due to the outward form and substance, so different from the form and substance of the higher "living things." But we have seen that the Diatoms took on shapes of crystals, and that the outer shell or covering was similar to silicia, a mineral, the inner substance being but a tiny speck of plasm, similar to that of the substance of a plant cell. And then we may look to the tiny bit of chalk dust which was once the skeleton-form of a living creature. The same is true of coral. In the very low forms of life, the skeleton, or form, is the thing most apparent, the plasm of "living substance" being still smaller, and less apparent. And yet, the skeleton, or shell, was formed by the vital processes of the creature, and was a part of its "body," just as is the skeleton or bony structure of the higher animals. And, in the same sense it is "living substance." And, remember, that there is but little difference between these "bodies" of the low forms of life, and the bodies of crystals. And the chemical constituents of its plasmic inner body is but slightly different from that of the crystals. And its nature and vital process are by a shade higher in the scale than those of the crystals. You may ask why we have said so much of Crystals. The reason is just this--Science has begun to think of Crystals as semi-living things, and its most advanced investigators and thinkers go further and assert that "the Crystals are alive--Crystallization is an evidence of life process." Crystals arrange themselves in well-known and well-defined shapes, direction and order of formation being observed implicitly. Each crystal follows the laws and habits of its kind, just as do plants and animals. Its lines of crystallization are mathematically perfect, and according to the laws of its being. Not only this, but some substances have a range of six or seven different forms of crystal-forms possible to them. In some cases a chemical element assumes one form of crystallization when it manifests as one mineral, and a second form when it manifests in another form--in each case however, it manifests along well-known and recognized courses of action, movement, and shapes.