Page:An introduction to physiological and systematical botany (1st edition).djvu/104

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ously, provided their health be good, as in their natural maritime places of growth.

Sugar, more or less pure, is very generally found in plants. It is not only the seasoning of most eatable fruits, but abounds in various roots, as the Carrot, Beet and Parsnip, and in many plants of the grass or cane kind besides the famous Sugar Cane, Saccharum officinarum. There is great reason to suppose Sugar not so properly an original secretion, as the result of a chemical change in secretions already formed, either of an acid or mucilaginous nature, or possibly a mixture of both. In ripening fruits this change is most striking, and takes place very speedily, seeming to be greatly promoted by heat and light. By the action of frost, as Dr. Darwin observes, a different change is wrought in the mucilage of the vegetable body, and it becomes starch.

A fine red liquor is afforded by some plants, as the Bloody Dock or Rumex sanguineus, Engl. Bot. t. 1533, the Red Cabbage and Red Beet, which appears only to mark a variety in all these plants, and not to constitute a specific difference. It is however perpetuated by seed.