[Sidenote: Sources of pentoses]
Pentoses form a group of sugars, the chemical formula of which contains
five atoms of carbon. Each different pentose could be studied in detail
by the chemist, but the pentoses are of no particular interest to the
food scientist. They exist, however, in the coarse parts of plants,
such as stalks and leaves, and are of considerable importance in animal
feeding. From the standpoint of human food we will remember that the
carbohydrates of green plants contain a percentage of these pentoses,
but as they are never removed from the plant separately, as are other
sugars, we must consider their physiological effect in the particular
plant rather than separately.