part 27

.

[628] From _amargoso_, bitter.

[629] C. De Candolle, in _Monogr. Phanerogamar._ i. (1878) 459.

[630] It is mentioned in Chinese writings dating long prior to the Christian era.—Bretschneider, _Chinese Botanical Works_, 1870. 12.

[631] _Colloquios dos Simples, &c._, Goa, 1563 _Colloq._ xl. p. 153.

[632] _Tractado de las Drogas y Medicinas de las Indias Orientales_, Burgos, 1578, cap. 43.

[633] Waring, in _Pharmacopœia of India_, 1868. 443.

[634] We are indebted for it to Mr. Broughton of Ootacamund.

=Microscopic Structure=—The suberous coat consists of numerous layers of ordinary cork-cells, which cover a layer of nearly cubic sclerenchymatous cells. This latter however is not always met with, secondary bands of cork (_rhytidoma_) frequently taking its place. The liber is commonly built up of strong fibre-bundles traversed by narrow medullary rays, and transversely separated by bands of parenchymatous liber tissue. Crystals of oxalate of calcium occur in the parenchyme more frequently than the small globular starch grains. The structure of the bark varies considerably according to the gradual development of the secondary cork-bands.

=Chemical Composition=—Margosa bark was chemically examined in India by Cornish[635] (1856), who announced it as a source of a bitter alkaloid to which he gave the name of _Margosine_, but which he obtained only in minute quantity as a “_double salt of Margosine and Soda_” in long white needles.

From the bitter oil of the seeds he isolated a substance which he called _Margosic Acid_, and which he doubted to be capable of affording crystallizable salts. The composition neither of this acid nor of margosine is known, nor have the properties of either been investigated.

The small sample of the bark at our disposal only enables us to add that an infusion produced with perchloride of iron a blackish precipitate, and that an infusion is not altered by tannic acid or iodohydrargyrate of potassium. If the inner layers of the bark are alone exhausted with water, the liquid affords an abundant precipitate with tannic acid; but if the _entire_ bark is boiled in water, the tannic matter which it contains will form an insoluble compound with the bitter principle, and prevent the latter being dissolved. It is thus evident that to isolate the bitter matter of the bark, it would be advisable to work on the liber or inner layers alone, which might readily be done, as they separate easily.

According to the recent researches of Broughton[636] the bitter principle is an amorphous resin soluble in the usual solvents and in boiling solutions of fixed alkalis. From the latter it is precipitated by acids, yet, probably, altered. Broughton ascribed the formula C₃₆H₅₀O₁₁ to this bitter resin purified by means of bisulphide of carbon, ether and absolute alcohol; it fused at 92° C. He obtained moreover a small quantity of a crystallized principle, which he believed to be a fatty body, yet its melting point of 175° C. is not in favour of this suggestion.

=Uses=—In India the bark is used as a tonic and antiperiodic, both by natives and Europeans. Dr. Pulney Andy of Madras has found the leaves beneficial in small-pox.

[635] _Indian Annals of Medical Science_, Calcutta, iv. (1857) 104.

[636] _Madras Monthly Journ. Med. Science_, quoted in _Pharm. Journ._ June 14, 1873, 992.

CORTEX SOYMIDA.

_Cortex Swieteniæ_; _Rohun Bark_.

=Botanical Origin=—_Soymida[637] febrifuga_ Juss. (_Swietenia febrifuga_ Willd.), a tree of considerable size not uncommon in the forests of Central and Southern India. The timber called by Europeans _Bastard Cedar_ is very durable and strong, and much valued for building purposes.

=History=—The introduction of Rohun Bark into the medical practice of Europeans is due to Roxburgh[638] who recommended the drug as a substitute for Cinchona, after numerous trials made in India about the year 1791. At the same time he sent supplies to Edinburgh, where Duncan made it the subject of a thesis[639] which probably led to it being introduced into the materia medica of the Edinburgh Pharmacopœia of 1803, and of the Dublin Pharmacopœia of 1807.

Though thus officially recognized, it does not appear that the bark came much into use or by any other means fulfilled the expectations raised in its favour. At present it is regarded simply as a useful astringent tonic, and as such it has a place in the _Pharmacopœia of India_ (1868).

=Description=—Our specimen of Rohun bark[640] which is from a young tree, is in straight or somewhat curved, half-tubular quills, an inch or more in diameter and about ⅕ of an inch in thickness. Externally it is of a rusty grey or brown, with a smoothish surface exhibiting no considerable furrows or cracks, but numerous small corky warts. These form little elliptic scars or rings, brown in the centre and but slightly raised from the surface. The inner side and edges of the quills are of a bright reddish colour.

A transverse section exhibits a thin outer layer coloured by chlorophyll, and a middle layer of a bright rusty hue, traversed by large medullary rays and darker wedge-shaped rays of liber. The latter has a fibrous fracture, that of the outer part of the bark being rather corky or foliaceous. The whole bark when comminuted is of a rusty colour, becoming reddish by exposure to air and moisture. It has a bitter astringent taste with no distinctive odour. The older bark frequently half an inch thick and fibrous, has a thick ragged corky layer of a rusty blackish-brown colour, deeply fissured longitudinally, and minutely cracked transversely. Old bark, according to Dymock (1877), is generally in half quills of a rich red-brown colour.

=Microscopic Structure=—The bark presents but few structural peculiarities. The ring of liber is made up of alternating prosenchymatous and parenchymatous tissue. In the latter the larger cells are filled with mucilage, the others with starch. The prosenchymatous groups of the liber exhibit that peculiar form we have already described as _hornbast_ (p. 74); it chiefly contains the tannic matter, besides stellate crystals of oxalate of calcium which are distributed through the whole tissue of the bark. The medullary rays are of the usual form, and contain starch granules. The corky coat is built up of a smaller number of vaulted cells.

[637] From _Sómida_, the Teluga name of the tree; _Róhan_ is its name in Hindustani.—Fig. in Bentley and Trimen, _Med. Plants_,