Gums

GUMS (Gummi), a thick, mucilaginous sap that exudes either spontaneously or from incisions and wounds on the bark of many trees. In a living plant, gums are formed through a special mucilaginous degeneration of the cellulose of the parenchyma cell walls, as well as the starch located inside the cells. In many plants, gums are formed normally, physiologically, in small quantities, but abundant gum formation is already considered a pathological process, arising as a result of injury and leading to the filling of the formed wound with mucus. The gums used in technology and medicine are of pathological origin. The formed gums are not involved in the general metabolism of plants. In appearance, gum preparations usually present as rounded or flat pieces, for some species of gum quite characteristic, transparent or only translucent, colorless or colored up to brown; they have no odor, are tasteless or have a weak sweetish-mucilaginous taste. In water, some gums dissolve completely, forming colloidal solutions, others only swell; they are insoluble in alcohol, ether, and other organic solvents; in a 60% solution of chloral hydrate, almost all gums are soluble; all of them are colloids. Chemically, they have been insufficiently studied; according to their main constituent part, they are divided into arabin, cerasin, and bassorin gums. Arabin gums, most of which are soluble in water, consist mainly of arabic acid, which decomposes into galactose, arabinose, and (in the opinion of O. Sullivan) a special gum acid of the composition C₁₂H₂₂O₁₁, forming together with diaraban, digalactan a special glycoside-gum acid: C₄₄H₆₈O₃₅ = C₁₂H₂₂O₁₁ + C₁₂H₂₀O₁₀ + C₂₀H₂₆O₁₄ (gum acid, galactan, araban). This acid is often given a different formula: (C₁₂H₂₀O₁₀.H₂O)_n. This acid in gums is bound with various amounts of calcium, potassium, and magnesium. Arabin gums include: gum arabic (see), East Indian (amrad, ghatti), acajou, and others. Cerasin gums are obtained mainly from trees of the family Amygdaleae; this includes so-called cherry glue, plum, apricot, etc.; the composition is close to arabic acid, which, when heated to 120°, partially converts into cerasin. None of these gums find medical application. Bassorin gums have been studied even less; they include: tragacanth, kutera, bassora, moringa, and other gums. In technology, gums are used as adhesive and dressing agents in calico printing, in the manufacture of watercolors, inks, matches, etc.; in medicine, as enveloping agents, as an additive to physiological solution for intravenous infusions, etc. Natives often use gums for food. In addition to pure gums, mixtures of gums with resins are often produced in plants, so-called gum-resins (Gummi-resinae); some of them have medical application, such as, for example, gamboge (see), euphorbium (see Euphorbium), and some others; mixtures with essential oils are also produced, so-called oil-gum-resins (Gummi-resinae-oleosae), such as, for example: Asa foetida, ammoniac, galbanum (see), olibanum, myrrh, and others.

D. Glimberg.