- One of a large series of amorphous or crystalline
substances, occurring very widely distributed in plants, rarely in
animals, and regarded as influental agents in the formation and
disposition of the sugars. They are frequently of a bitter taste, but,
by the action of ferments, or of dilute acids and alkalies, always
break down into some characteristic substance (acid, aldehyde, alcohol,
phenole, or alkaloid) and glucose (or some other sugar); hence the
name. They are of the nature of complex and compound ethers, and
ethereal salts of the sugar carbohydrates.