Radix Scillæ; Squill; F. Bulbe ou squames de Scille, Ognon marin; G. Meerzwiebel.
Botanical Origin—Urginea maritima Baker[2582] (Scilla maritima L., Urginea Scilla Steinheil). It is found generally in the regions bordering the Mediterranean, as in Southern France, Italy, Dalmatia, Greece, Asia Minor, Syria, North Africa and the Mediterranean islands. In Sicily, where it grows most abundantly, Urginea ascends to elevations of 3000 feet. It is also very common throughout the South of Spain, where it is by no means confined to the coast; it occurs also in Portugal. In the Riviera of Genoa the peasants like to see it growing under the fig trees.
Two varieties of squill, termed respectively white and red, are distinguished by druggists. In the first, the bulb-scales are colourless; in the second they are of a roseate hue. No other difference in the plants can be pointed out, nor have the two varieties distinct areas of growth.
History—Squill is one of the most ancient of medicines. Epimenides, a Greek who lived in the 30th Olympiad, is said to have made much use of it, from which circumstance it came to be called Epimenidea[2583]. It is also mentioned by Theophrastus, and was probably well known to all the ancient Greek physicians. Pliny was not only acquainted with it, but had noticed its two varieties. Dioscorides describes the method of making vinegar of squills; and a similar preparation, as well as compounds of squill with honey, were administered by the Arabian physicians, and still remain in use. The medical school of Salerno preferred the red variety of the drug, which on the whole is not frequently met with in mediæval literature.
Description—The bulb of squill is pear-shaped, and of the size of a man’s fist or larger, often weighing more than four pounds. It has the usual structure of a tunicated bulb; its outer scales are reddish-brown, dry, scarious, and marked with parallel veins. The inner are fleshy and juicy, colourless or of a pale rose tint, thick towards the middle, very thin and delicate at the edges, smooth and shining on the surface. The fresh bulb has a mucilaginous, bitter, acrid taste, but not much odour.
For medicinal use, squill is mostly imported ready dried. The bulbs are collected in the month of August, at which period they are leafless, freed from their dry outer scales, cut transversely into thin slices, and dried in the sun. Thus prepared, the drug appears in the form of narrow, flattish or four-sided curved strips, 1 to 2 inches long, and ⅜ to ⅝ of an inch wide, flexible, translucent, of a pale dull yellowish colour, or when derived from the red variety, of a decided roseate hue. When thoroughly dried, they become brittle and pulverizable, but readily absorb water to the extent of about 11 per cent. Powdered squill by the absorption of water from the air, readily cakes together into a hard mass.
Microscopic Structure—The officinal portion of the plant being simply modified leaves, has the histological characters proper to many of those organs. The tissue is made up of polyhedral cells, covered on both sides of the scales by an epidermis provided with stomata. It is traversed by numerous vascular bundles, and also exhibits smaller bundles of laticiferous vessels. If thin slices of squill be moistened with dilute alcohol, most of the parenchymatous cells are seen to be loaded with mucilage, which contracts into a jelly on the addition of alcohol. In the interior of this jelly, crystalline particles are met with consisting of oxalate of calcium. This salt is largely deposited in cells, forming either bundles of needle-shaped crystals, or large solitary square prisms, frequently a millimetre long. In either case they are enveloped by the mucilaginous matter already mentioned. Oxalate of calcium as occurring in other plants has been shown in many instances to originate in the midst of mucilaginous matter. The fact is remarkably evident in Scilla, especially when examined in polarized light.
On shaking thin slices of the bulb with water, the crystals are deposited in sufficient quantity to become visible to the naked eye, though their weight is actually very small. Direct estimation of the oxalic acid (by titration with chamæleon solution) gave us only 3·07 per cent. of C₂CaO₄,3H₂O from white squill dried at 100° C., which moreover yielded only 2 to 5 per cent. of ash. It is these extremely sharp brittle crystals which occasion the itching and redness, and sometimes even vesication, which result from rubbing a slice of fresh squill on the skin. These effects, which have long been known, were attributed to a volatile acrid principle, until their true cause was recognized by Schroff.[2584]
The mucilage also contains albuminous matters, hence the orange colour it assumes on addition of iodine. The vascular bundles are accompanied by some rows of longitudinally extended cells, containing a small number of starch granules. In the red squill the colouring matter is contained in many of the parenchymatous cells, others being entirely devoid of it. It turns blackish-green if a persalt of iron be added.
Chemical Composition—The most abundant among the constituents of squill are mucilaginous and saccharine matters. Mucilage may be precipitated by means of neutral and basic acetate of lead, yet there remains in solution another substance of the same class, called Sinistrin. It was discovered in 1879 by Schmiedeberg, who obtained it by mixing the powder of squill, either red or white, with a solution of basic acetate of lead in slight excess. The gummy matters thus forming insoluble lead compounds being removed, the liquid is deprived of the lead and mixed with slaked lime. An insoluble compound of sinistrin and calcium separates and yields the former on decomposing the well washed precipitate with carbonic acid. The small amount of calcium remaining in the filtrate is to be removed by adding cautiously to the warm solution the small quantity just required of oxalic acid. Lastly, sinistrin is thrown down by alcohol. It is a white amorphous powder, on exposure to air soon forming transparent brittle lumps. The composition of sinistrin is that of dextrin = C₆H₁₀O₅, both these substances being very closely allied, yet the aqueous solution of sinistrin deviates the plane of polarization to the left. The rotatory power appears not to be much influenced by the concentration or the temperature of the solution of sinistrin.