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The tree blossoms early in summer, producing numerous clusters of whitish flowers; in this country it only attains a height of 15 or 16 feet.
To-day, the Manna of commerce is collected exclusively in Sicily, from cultivated trees, exported from Palermo. The trees are grown in plantations placed about 7 feet apart. When from eight to ten years old, when the trunk is at least 3 inches in diameter, the collection of Manna is begun. In July and August, when the trees have ceased to put forth leaves freely, a vertical series of oblique incisions are made in the bark on alternate sides of the trunk. Dry, warm weather is essential for a good crop of the Manna which exudes. The larger pieces of incrustation that form, and which are collected in September and October, when the heat has begun to moderate, are known as Flake Manna, and this is the best. It is put on the market in long pieces or granulated fragments of a whitish and pale yellow colour, irregular on one side and smoother and curved on the other, rarely more than 1 inch broad and 2 to 3 inches or more long.
The pieces adhering to the stem after the finer pieces have been gathered are scraped off and form part of the small Manna of commerce. The pieces that form on the lowest incisions, or the pieces that are collected on tiles placed under the tree, and known as 'gerace,' are less crystalline, more glutinous, and are in moist adhesive masses of a dark brown colour. These are less esteemed.
---Medicinal Action and Uses---Manna has a peculiar odour and a sweetish taste.
It was formerly used in medicine as a gentle laxative, but is now chiefly used as a children's laxative or to disguise other medicines.
It is a nutritive and a gentle tonic, usually operating mildly, but in some cases produces flatulence and pain.
It is still largely consumed in South America and is official in the United States Pharmacopoeia.
It is generally given dissolved in water or some aromatic infusion, but the best Flake Manna may be administered in substance, in doses of a teaspoonful up to 1 or 2 oz.
Usually it is prescribed with other purgatives, particularly senna, rhubarb, magnesia and the neutral salts, the taste of which it conceals while it adds to the purgative effect.
For infants, a piece about the size of a hazel-nut is dissolved in a little warm water and added to the food. To children, 30 to 60 grams may be given dissolved in warm milk or a mixture prepared with syrup, or syrup of senna and dill water.
Syrups of Manna are prepared with or without other purgatives.
Manna is sometimes used as a pill excipient, especially for calomel.
Under the name of Dulcinol, a mixture of Manna and common salt has been recommended by Steinberg in 1906 as a sweetening agent in diabetes, the dose 1/2 to 1 OZ.
The Codex of the British Pharmacopceia contains a Syrup of Manna to be prescribed as a mild laxative for children, in the proportion of 1 part of Manna to 10 of water.
The Compound Syrup of Manna of the B.P. Codex is stronger than the Syrup of Manna and contains Senna and fennel in addition, the dose being 1 to 4 fluid drachms.
---Constituents---Manna of the best quality dissolves in about 6 parts of water, forming a clear liquid. It has no bitterness or acridity.
The chief constituent of Manna is a peculiar, crystallizable, sweet principle called Mannite or Manna Sugar, present to the extent of about 70 per cent. It also contains a fluorescent body named Fraxin, which occasionally gives a greenish colour to Manna and on which is thought to depend its purgative property. Some true sugar and a small quantity of mucilage are also present.
Mannite is white, inodorous, crystallizable in semi-transparent needles of a sweetish taste, soluble in 5 parts of cold water, scarcely soluble in cold alcohol, but readily dissolved by alcohol when hot and deposited when cool. Unlike sugar, it is incapable of undergoing vinous fermentation.
---Definition of Manna in Italy---An Italian Decree-law, dated August 12, 1927, dealing with the repression of fraud and adulteration in the preparation and trade in substances of vegetable origin, states that the name 'Manna' is reserved for the product obtained by incision into the cortex of the flowering or Manna Ash (F. ornus or F. excelsior). It is forbidden to prepare, sell, or expose for sale or introduce into trade Manna containing milk sugar, starchy matter, or containing foreign substances of whatever nature, other than those bodies which are present naturally as impurities in the normal proportions existing in the various types of Manna.
In Italy, Mannite is prepared for sale in the shape of small cones, resembling loaf sugar in shape, and is frequently prescribed in medicine instead of Manna.
The term 'Manna' is extremely old and is applied to the saccharine exudence of a number of plants, e.g. Quercus Vallones and persica (Oak Manna); Alhagi maurorum (Alhagi Manna), Tamarix gallica, var. mannifera (Tamarisk Manna); Larix Europaea (Briancon Manna).
The Manna of the present day appears to have been unknown before the fifteenth century. In the sixteenth century, it was collected in Calabria, but none is now brought into commerce from this part of Italy.
Although the name Manna, at first applied to the Manna of the Scriptures, has (as stated) also been applied to various saccharine substances of different origin, none of these corresponds in any way to the Manna of Scripture, inasmuch as they are saccharine substances and do not become corrupt in a night.
The Manna of the biblical narrative answers otherwise in its description to the Tamarisk Manna, exuded in June and July from the slender branches of Tamarisk gallica, var. mannifera, in the form of honey-like drops, which in the cool temperature of the early morning are found in the solid state. This secretion is caused by the puncture of an insect, Coccus manniparus. In the valleys of the peninsula of Sinai, this Manna is collected by the Arabs and sold by them to the monks of St. Catherine, who dispose of it to the pilgrims visiting the convent, under the name of 'gazangabin,' which means 'Tamarisk Honey.' It appears to consist of cane sugar, inverted sugar, and dextrin.
A report issued in 1927 by an expedition of entomologists from the Hebrew University of Jerusalem declares that Manna is not an exudation from the Tamarisk tree, as is popularly supposed, but an excretion from the bodies of the coccid insects themselves. Clear, syrup-like drops (the report states) come from the abdomen of the insects and fall to the ground, where they form grains of sugar, ranging from the size of a pinhead to that of a pea. The amount varies with the abundance or scarcity of the winter rains and the Bedouins assert that during a good season a man can collect nearly 3 1/2 lb. in a day. The expedition, which was led by Dr. Fritz Bodenheimer of the Zionist experimental agricultural station, observed Manna deposits throughout the long stretch of country which was covered by its journey. The report goes on to state that 'modern science, it seems, was equally ignorant of the true nature of manna till now, and it has been revealed by descendants of those wanderers in the wilderness.'
The only substance which in all respects seems to agree with the Manna of the Israelites is that described a few years ago by Mr. A. J. Swann, in his book on Fighting the Slave Driver in Central Africa. The Manna which he saw on the plateaux between the lakes Tanganyika and Nyasa occupied by the Ananbwi tribe Mr. Swann describes as possessing all the characters of the Manna which is said to have fallen for the benefit of the Israelites. In appearance it resembled coriander seed, was white in colour like hoar-frost and sweet to taste, melted in the sun, and if kept overnight was full of worms in the morning. It required to be baked to keep it any length of time. A cake of this Manna was baked and sent to England, but no one seemed able to identify it, though there can be little doubt that it is a small fungus. The baking process would, of course, destroy its structure, and it is evident that to determine its nature, some of the Manna should be sent home in formaldehyde or corrosive sublimate, when it would be quite possible to make out its structure and classification and to describe it, if new. It does not appear to be regular in its occurrence, as travellers have reported its appearance only at long intervals.
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