snake-weed that was brought from Virginia and grew with Mr. John Tradescant at South Lambeth, anno 1632." It was very briefly noticed by Cornuti in his Canadensium Plantarum Historia (1635), and in a much more intelligent manner by Parkinson in 1640. These authors, as well as Dale (1693) and Geoffroy (1741), extol the virtues of the root as a remedy for the bite of the rattlesnake, or of a rabid dog. Serpentary was introduced into the London Pharmacopoeia in 1650.

Description-The snake-root of commerce includes the rhizome, which is knotty, contorted, scarcely 1 inch in length by of an inch in thickness, bearing on its upper side the short bases of the stems of previous years, and throwing off from the under, numerous, slender, inatted, branching roots, 2 to 4 inches long. The rhizome is often still attached to portions of the weak, herbaceous stem, which sometimes bears the fruit,-more rarely flowers and leaves. The drug has a dull brown hue, an aromatic odour resembling valerian but less unpleasant, and a bitterish aromatic taste, calling to mind camphor, valerian and turpentine.

Microscopic Structure-In the rhizome, the outer layer of the bark consists of a single row of cuboid cells; the middle cortical portion (mesophlæum) of about six layers of larger cells. In the liber, which is built up of numerous layers of smaller cells, those belonging to the medullary rays are nearly cuboid with distinctly porous walls, those of the liber bundles being smaller and arranged in a somewhat crescentshaped manner. Groups of short, reticulated or punctuated vessels alternate in the woody rays with long, porous, ligneous cells, those close to the pith having thick walls. The largest cells of all are those composing the pith; the latter, seen in transverse section, occupies not the very centre of the rootstock, but is found nearer to its upper side. The rootlets exhibit a central fibro-vascular bundle, surrounded by a nucleus sheath. In the mesophloum both of the rootstock and the rootlets, there occur a few cells containing a yellow essential oil. The other cells are loaded with starch.

Chemical Composition-Essential oil exists in the drug to the extent of about per cent.; and resin in nearly the same proportion. The outer cortical layer, as well as the zone of the nucleus-sheath, contains a little tannin, and a watery infusion of the drug is coloured greenish by perchloride of iron. Neutral acetate of lead precipitates some mucilage as well as the bitter principle (the so-called Aristolochin of Chevallier?) which latter may also be obtained by means of tannic acid. It is an amorphous, bitter substance, which deserves further investigation. By an alkaline solution of tartrate of copper the presence in serpentary of sugar is made evident.

Commerce-Virginian snake-root is imported from New York and Boston, in bales, casks or bags.

Uses The drug is employed in the form of an infusion or tincture as a stimulating tonic and diaphoretic; it is more often prescribed in combination with cinchona bark than by itself. Its ancient reputation for the cure of snake-bites is now disregarded.

Adulteration and Substitution-Virginian snake-root is said to be sometimes adulterated with the root of Spigelia Marilandica L.,

which has neither its smell nor taste (see p. 389); or with that of Cypripedium pubescens L., which it scarcely at all resembles. It is not uncommon to find here and there in the serpentary of commerce, a root of Panax quinquefolium L. accidentally collected, but never added for the purpose of adulteration.

The root of Aristolochia reticulata Nutt., a plant of Louisiana and Arkansas, has been brought into commerce in considerable quantity as Texan or Red River Snake-root.1 We are indebted for an authentic specimen from the Cherokee country, to Mr. Merrell, a large dealer in herbs at St. Louis, Missouri, who states that all the serpentary grown south-west of the Rocky Mountains is the produce of that species. The late Prof. Parrish of Philadelphia was kind enough to supply us with specimens of the same drug, as well as with reliable samples of true Virginian or Middle States Snake-root.

The Texan snake-root is somewhat thicker and less matted than that derived from A. Serpentaria, but has the odour and taste of the latter; some say it is less aromatic. The plant, portions of which are often present, may be easily distinguished by its leaves being coriaceous, sessile and strongly reticulated on their under surface.

CUPULIFERÆ.

CORTEX QUERCUS.

Oak Bark; F. Ecorce de Chêne; G. Eichenrinde.

Botanical Origin-Quercus Robur L., a tree, native of almost the whole of Europe, from Portugal and the Greek Peninsula as far north as 58° N. lat. in Scotland, 62° in Norway, and 56° in the Ural Mountains.

There are two remarkable forms of this tree which are regarded by many botanists as distinct species, but which are classed by De Candolle as sub-species.

Sub-species I. Pedunculata-with leaves sessile or shortly stalked, and acorns borne on a long peduncle.

Sub-species II. Sessiliflora-with leafstalks more or less elongated, and acorns either sessile or growing on a short peduncle.

Both forms occur in Britain. The first is the common oak of the greater part of England and the lowlands of Scotland. The second is frequently scattered in woods in which the first variety prevails, but it rarely constitutes the mass of the oak woods in the south of England. In North Wales however, in the hilly parts of the north of England, and in Scotland, it is the commoner of the two forms (Bentham).

History-The astringent properties of all parts of the oak3 were well known to Dioscorides, who recommends a decoction of the inner bark in colic, dysentery and spitting of blood. Yet oak bark seems at no time to have been held in great esteem as a medicine, probably on

1 Wiegand in American Journ. of Pharm. X. (1845) 10-also Proceedings of the American Pharmaceutical Association, xxi. (1873) 441.

2 Prodromus, xvi. (1864) sect. 2. fasc. 1. 3 Probably not Q. Robur L.

account of its commonness; and it is now almost superseded by other astringents. For tanning leather, it has always been largely employed.

Description-For medicinal use, the bark of the younger stems or branches is collected in the early spring. It varies somewhat in appearance according to the age of the wood from which it has been taken: that usually supplied to English druggists is in channelled pieces of variable length and a tenth of an inch or less in thickness, smooth, of a shining silvery grey variegated with brown, dotted over with little scars. The inner surface is light rusty-brown, longitudinally striated. The fracture is tough and fibrous. A transverse section shows a thin, greenish cork-layer, within which is the brown parenchyme, marked with numerous rows of translucent colourless spots. The smell of dry oak bark is very faint; but when the bark is moistened, the odour of tan becomes evident. The taste is astringent and in old barks, slightly bitter.

Microscopic Structure-The outer layer of young oak bark consists of small flat cork-cells; the middle layer of larger thick-walled cells, slightly extended in a tangential direction and containing brown grains and chlorophyll. This tissue passes gradually into the softer narrower parenchyme of the inner bark, which is irregularly traversed by narrow medullary rays. It exhibits moreover a ring, but slightly interrupted, of thick-walled cells (sclerenchyme) and isolated shining bundles of liber fibres.

Groups of crystals of calcium oxalate are frequent in the middle and inner bark, but the chief constituents of the cells are brown granules of colouring matter and tannin. As the thickness of the bark increases, the liber is pushed more to the outside, the middle cortical layer being partly thrown off by secondary cork-formation (rhytidoma, see p. 317). Hence the younger barks, which alone are medicinal, are widely different from the older in structure and appearance.

Chemical Composition-The most interesting constituent is a peculiar kind of tannin. Stenhouse pointed out in 1843, that the tannic acid of oak bark is not identical with that of nutgalls; and such many years afterwards was proved to be the case.

The first-named substance, now called Querci-tannic Acid, yields by destructive distillation, pyrocatechin but not pyrogallol. It does not afford by oxidation, gallic acid. A solution of gelatine is precipitated by querci-tannic acid as well as by gallo-tannic acid; yet the compound formed with the latter is very liable to putrefaction, whereas the tannin of oak bark, which is accompanied by a large amount of extractive matter, furnishes a stable compound, and is capable of forming good leather.

As querci-tannic acid has not yet been isolated in a pure state, the exact estimation of the strength of the tanning principle in oak bark has not been accomplished, although it is important from an economic as well as from a scientific point of view. The best method is that of Neubauer (1873), which depends upon the amount of permanganate of potassium decomposable by the extract of a given weight of oak bark. Neubauer found in the bark of young stems, as grown for tanning purposes, from 7 to 10 per cent. of querci-tannic acid, soluble in cold water.

A colourless, crystallizable, bitter, neutral substance, soluble in water but not in absolute alcohol or ether, was extracted from oak bark in

1843 by Gerber, and named Quercin. It requires further examination: C. Eckert could not detect its existence in young oak bark.

1

Uses-Occasionally employed as an astringent, chiefly for external

application.

GALLÆ

HALEPENSES.

Galla Turcica; Galls, Nutgalls, Oak Galls, Aleppo or Turkey Galls; F. Noix de Galle, Galle d'Alep; G. Levantische oder Aleppische Gallen, Galläpfel.

Botanical Origin-Quercus Lusitanica Webb, var. infectoria (Q. infectoria Oliv.),2 a shrub or rarely a tree, found in Greece, Asia Minor, Cyprus and Syria. It is probable that other varieties of this oak, as well as allied species, contribute to furnish the Aleppo galls of commerce.

History-Oak galls are named by Theophrastus who lived in the 3rd or 4th century B.C., and were well known to other ancient writers. Pliny 3 mentions the interesting fact that paper saturated with an infusion of galls may be used as a test for discovering sulphate of iron, when added as an adulteration to the more costly verdigris: this, according to Kopp, is the earliest instance of the scientific application of a chemical reaction. For tanning and dyeing, galls have been used from the earliest times.

4

Nutgalls have long been an object of commerce between Western Asia and China. Barbosa in his Description of the East Indies 5 written in 1514, calls them Magican and says they are brought from the Levant to Cambay by way of Mekka, and that they are worth a great deal in China and Java. From the statements of Porter Smith, we learn that they are still prized by the Chinese.

Formation-Many plants are punctured by insects for the sake of depositing their eggs, which operation gives rise to those excrescences which bear the general name of galls

Oaks are specially liable to be visited for this purpose by insects of the order Hymenoptera and the genus Cynips, one species of which, Cynips Galla tinctoria Olivier (Diplolepis Galla tinctoria Latreille), occasions the galls under notice.

The female of this little creature is furnished with a delicate borer or ovipositor, which she is able to protrude from the extremity of the abdomen: by means of it, she pierces the tender shoot of the oak, and deposits therein one or more eggs. This minute operation occasions an abnormal affluence to the spot, of the juices of the plant, the result of which is the growth of an excrescence often of great magnitude, in the centre of which (but not as it appears until the gall has become fullgrown) the larva is hatched and undergoes its transformations.

1 Wittstein, Vierteljahresschr. für prakt. Pharm. xiii. (1864) 494.

2 De Candolle, Prodromus, xvi. sect. 2. fasc. i. 17.

3 Lib. 34. c. 26.

4 Geschichte der Chemie, ii. (1844) 51.

5 Published by the Hakluyt Society, Lond. 1866. 191.

6 Nearly the same name is still used in

the Tamil, Telugu, Malayalim and Canarese languages.

7 Mat. Med. and Nat. Hist. of China, 1871. 100.

8 French writers, as Moquin-Tandon, distinguish the thick-walled galls of Cynips from the thin, capsular galls formed by Aphis, terming the former galles and the latter coques (shells).

When the larva has assumed its final developement and become a winged insect, which requires a period of five to six months, the latter bores itself a cylindrical passage from the centre of the gall to its surface, and escapes.

In the best kind of gall found in commerce, this stage has not yet arrived, the gall having been gathered while the insect is still in the larval state. In splitting a number of galls, it is not difficult to find specimens in all stages, from those containing the scarcely distinguishable remains of the minute larva, to those which show the perfect insect to have perished when in the very act of escaping from its prison.

1

Description-Aleppo galls are spherical, and have a diameter of to of an inch. They have a smooth and rather shining surface, marked in the upper half of the gall by small pointed knobs and ridges, arranged very irregularly and wide apart; the lower half is more frequently smooth. The aperture by which the insect escapes is always near the middle. When not perforated, the galls are of a dark olive. green, and comparatively heavy; but after the fly has bored its way out, they become of a yellowish brown hue, and lighter in weight. Hence the distinction in commerce of Blue or Green Galls, and White Galls.

The

Aleppo galls are hard and brittle, splitting under the hammer; they have an acidulous, very astringent taste followed by a slight sweetness, but have no marked odour. Their fractured surface is sometimes closegrained, with a waxy or resinous lustre; sometimes (especially towards the kernel-like centre) loosely granular, or sometimes again it exhibits a crystalline-looking radiated structure or is full of clefts. The colour of the interior varies from pale brown to a deep greenish yellow. central cavity, sometimes nearly of an inch in diameter, which served as a dwelling for the insect, is lined with a thin hard shell. If the insect has perished while still very young, the central cavity and the aperture contain a mass of loose starchy cellular tissue, or its pulverulent remains if the insect has not been developed at all, the centre of the gall is entirely composed of this tissue.

Microscopic Structure-The cellular tissue of the gall is formed in the middle layer of large spherical cells with rather thick porous walls, becoming considerably smaller towards the circumference. The outermost rows are built up of cells having but a very small lumen and comparatively thick walls, so that they form a sort of rind. Here and there throughout the entire tissue, there occur isolated bundles of vessels which pass through the stalk into the gall. Towards the kernel, the parenchyme gradually passes into radially-extended, wider, thin-walled cells, the walls of which are marked with spiral striæ. The hard shell of the chamber2 is composed of larger, radially-extended, thickwalled cells, with beautifully stratified porous walls. On the inner side of this shell there are found after the escape of the insect, the remains of the starchy tissue already mentioned, which originally filled the chamber and had been consumed by the insect as nourishment.

1 There are many other varieties of oak gall, for descriptions of some of which, see Guibourt, Hist. des Drogues, ii. (1869) 292; and for information on the various gallinsects of the family Cynipsida and the excrescences they produce, consult a paper by

Abl in Wittstein's Vierteljahresschrift für prakt. Pharm. vi. (1857) 343-361.

2 Couche protectrice of Lacaze-DuthiersRecherches pour servir à l'histoire des galles. -Ann. des Sciences Nat., Bot., xix. (1853) 273-354.