GLUCOSE occurs abundantly in animals and plants, either alone or in combination, combined with fructose (fruit-sugar or laevulose) as sucrose (cane-sugar), with galactose as lactose (milk sugar), with itself as maltose (malt-sugar), and so on. It is an aldose (aldehyde-alcohol) of the hexose class, having the formula and is also known as grape sugar or dextrose. The latter name refers to the fact that its solutions rotate the plane of polarized light to the right. (See CARBOHYDRATES.) When pure, it is a white, crystalline powder, but it is more often seen as a yel lowish, highly concentrated syrup of a sickly sweet taste; it is also obtainable as warty masses of its hydrate, Glucose is readily prepared from starch or from cane sugar by the action of dilute acids, and is easily fermented by yeast to give alcohol. It is excreted in considerable quantities by persons suffering from diabetes mellitus. It has very many uses in the food industries, as a sweetening agent and as a substitute for cane sugar in various processes where fermentation plays an essential role, and to a lesser extent in pharmacy. (See DEXTRIN.)