part 34

(1878).

[2068] _Mat. Med. Americ._, Erlangæ, 1787. 32.

[2069] _Proceedings of the American Pharmaceutical Association for 1873_, xxi. 435.

=Microscopic Structure=—The transverse section shows a series of undulating layers of large yellowish bundles of soft liber-fibres, alternating with small brown parenchymatous bands. The whole tissue is traversed by numerous narrow medullary rays, and interrupted by large intercellular mucilage-ducts. In order to examine the latter, longitudinal sections ought to be moistened with benzol, aqueous liquids causing great alteration. In a longitudinal section, the mucilage-ducts are seen to be 70 to 100 mkm. long, and to contain colourless masses of mucilage, distinctly showing a series of layers. Crystals of calcium oxalate, as well as small starch grains, are very plentiful throughout the surrounding parenchyme.

=Chemical Composition=—The most interesting constituent of the bark is mucilage, which is imparted to either cold or hot water, but does not form a true solution. The bark moistened with 20 parts of water swells considerably, and becomes enveloped by a thick neutral mucilage, which is not altered either by iodine or perchloride of iron. This mucilage when diluted, even with a triple volume of water, will yield only a few drops when thrown on a paper filter. The liquid which drains out is precipitable by neutral acetate of lead. By addition of absolute alcohol, the concentrated mucilage is not rendered turbid, but forms a colourless transparent fluid deposit.

=Adulteration=—Farinaceous substances admixed to the powdered drug may be detected by means of the microscope.

=Uses=—Slippery Elm Bark is a demulcent like althæa or linseed. The powder is much used in America for making poultices; it is said to preserve lard from rancidity, if the latter is melted with it and kept in contact for a short time.

EUPHORBIACEÆ.

EUPHORBIUM.

_Euphorbium_, _Gum Euphorbium_; F. _Gomme-résine d’Euphorbe_; G. _Euphorbium_.

=Botanical Origin=—_Euphorbia resinifera_ Berg, a leafless, glaucous, perennial plant resembling a cactus, and attaining 6 or more feet in height. Its stems are ascending, fleshy and quadrangular, each side measuring about an inch. The angles of the stem are furnished at intervals with pairs of divergent, horizontal, straight spines about ¼ of an inch long, and confluent at the base into ovate, subtriangular discs. These spines represent stipules: above each pair of them is a depression, indicating a leaf-bud. The inflorescence is arranged at the summits of the branches, on stalks each bearing three flowers, the two outer of which are supported on pedicels. The fruit is tricoccous, ³/₁₀ of an inch wide, with each carpel slightly compressed and keeled.[2070]

The plant is a native of Morocco, growing on the lower slopes of the Atlas in the southern province of Suse. Dr. Hooker and his fellow-travellers met with it in 1870 at Netifa and Imsfuia,[2071] south-east of the city of Morocco, which appears to be its westward limit.

=History=—Euphorbium was known to the ancients. Dioscorides[2072] and Pliny[2073] both describe its collection on Mount Atlas in Africa, and notice its extreme acridity. According to the latter writer, the drug received its name in honour of Euphorbus, physician to Juba II., king of Mauritania. This monarch, who after a long reign died about A.D. 18, was distinguished for his literary attainments, and was the author of several books[2074] which included treatises on opium and euphorbium. The latter work was apparently extant in the time of Pliny.

[2070] Fig. in Bentley and Trimen’s _Med. Plants_,