Glucose or grape-sugar is the most important sugar known from the
standpoint of the physiological chemist. This sugar is normally found
in considerable quantities in human blood, and is absolutely essential
to the life-process, a fact which forms an amusing contrast with the
popular conception of the term glucose as something injurious or
poisonous.
[Sidenote: Sources of glucose]
Glucose is found in honey, and in nearly all fruits, grains, and sweets.
(For "Sweets" see Lesson VIII, Vol. II, p. 324). It may be taken into
the human body directly from such fruits, or it may originate by the
digestion of other carbohydrates.
Pure glucose crystallizes and resembles cane-sugar, but is not so sweet.
The glucose of commerce, sold as sirup, is a product manufactured from
corn, or other starches, and will be considered more in detail under the
heading _starch_. (See "Polysaccharids," p. 114).