part 5

(1876).

[822] _Hortus Americanus_, Kingston, Jamaica, 1794. 91.

[823] _Fifth Letter of Hernan Cortes to the Emperor Charles V._, Lond. (Hakluyt Society) 1868. 43.

[824] The first edition bears date 1535. We have used the modern one of Madrid, 1851-55, 4to., and may refer in particular to tom. i. lib. ix. c. 15, iii. lib. xxxi. c. 8 and c. 11.—See Appendix: Fernandez.

[825] 23 Eliz. c. 9.

[826] 13-14 Car. ii. c. 11. sect. 26 (A.D. 1662), by which the Act of Elizabeth was repealed.

[827] _Novus Orbis_, 1633. 274 and 265.

As a medicine, logwood was not employed until shortly before the year 1746, when it was introduced into the London Pharmacopœia under the name of _Lignum tinctile Campechense_.

=Description=—The tree is fit to be felled when about ten years old; the dark bark and the yellowish sapwood are chipped off, the stems cut into logs about three feet long, and the red heartwood alone exported. By exposure to air and moisture, the wood acquires externally a blackish-red colour; internally it remains brownish red. It splits well, although of a rather dense and tough texture.

The transverse section of a piece of logwood exhibits to the naked eye a series of very narrow concentric zones, formed by comparatively large pores, and of small parenchymatous circles separated by the larger and darker rings of the proper woody tissue. The numerous medullary rays are visible only by means of a lens. The wood has a pleasant odour.

For use in pharmacy, logwood is always purchased in the form of chips, which are produced by the aid of powerful machinery. The chips have a feeble, seaweed-like odour, and a slightly sweet, astringent taste, better perceived in a watery decoction than by chewing the dry wood, which however quickly imparts to the saliva its brilliant colour.

=Microscopic Structure=—Under a high magnifying power, the concentric zones are seen to run not quite regularly round the centre, but in a somewhat undulating manner, because they do not correspond, as in our indigenous woods, to regular periods of annual growth. The vascular bundles contain only a few vessels, and are transversely united by small lighter parenchymatous bands. The latter are made up of large, cubic, elongated or polygonal cells, each loaded with a crystal of oxalate of calcium. The large punctuated vessels having frequently 150 mkm. diameter, are surrounded by this woody parenchyme, while the prevailing tissue of the wood is composed of densely packed prosenchyme, consisting of long cylindrical cells (_libriform_) with thick, dark red-brown walls having small pores.

The medullary rays are of the usual structural character, running transversely in one to three straight rows; in a longitudinal section, the single rays show from 4 to 40 rows succeeding each other perpendicularly. No regular arrangement of the rays is obvious in a longitudinal section made in a tangential direction. The colouring matter is chiefly contained in the walls of the ligneous tissue and the vessels, and sometimes occurs in crystals of a greenish hue within the latter, or in clefts of the wood.

=Chemical Composition=—Logwood was submitted to analysis by Chevreul as early as the year 1810,[828] since which period all contributions to a knowledge of the drug refer exclusively to its colouring principle _Hæmatoxylin_, which Chevreul obtained in a crystallized state and called _Hématine_. The very interesting properties of this substance have been chiefly examined by Erdmann (1842) and by O. Hesse (1858-59).

[828] _Annals de Chimie_, lxxxi. (1812) 128.

Erdmann obtained from logwood 9 to 12 per cent. of crystallized hæmatoxylin, which he showed to have the formula C₁₆H₁₄O₆. In a pure state it is colourless, crystallizing with 1 or with 3 equivalents of water, and is readily soluble in hot water or in alcohol, but sparingly in cold water or in ether. It has a persistent sweet taste like liquorice. The crystals of hæmatoxylin acquire a red colour by the action of sunlight, as likewise their aqueous solution. They are decomposed by ozone but not by pure and dry oxygen. In presence of alkalis, hæmatoxylin exposed to the air quickly yields dark purplish violet solutions, which soon acquire a yellowish or dingy brownish colour; hence in analytical chemistry hæmatoxylin is used as a test for alkalis.

By the combined action of ammonia and oxygen, dark violet crystalline scales of _Hæmateïn_, C₁₆H₁₄O₆ + 3 OH₂, are produced.[829] They show a fine green hue, which is also very commonly observable on the surface of the logwood chips of commerce. Hæmateïn may again be transformed into hæmatoxylin by means of hydrogen or of sulphurous acid.

Hæmatoxylin separates protoxide of copper from an alkaline solution of the tartrate, and deviates the ray of polarized light to the right hand. It is not decomposed by concentrated hydrochloric acid; by melting hæmatoxylin with potash, pyrogallol (pyrogallic acid, C₆H₆O₃) is obtained. Alum and the salts of lead throw down precipitates from solutions of hæmatoxylin, the latter being of a bluish-black colour. Logwood affords upon incineration 3·3 per cent. of ash.

The colouring matter being abundantly soluble in boiling water, an _Extract of Logwood_ is also prepared on a large scale. It occurs in commerce in the form of a blackish brittle mass, taking the form of the wooden chest into which it is put while soft. The extract shares the chemical properties of hæmatoxylin and hæmateïn: whether it also contains gum requires investigation.

=Production and Commerce=—The felling and shipping of logwood in Central America have been described by Morelet,[830] who states that in the woods of Tabasco and Yucatan the trade is carried on in the most irrational and reckless manner. By advancing money to the natives, or by furnishing them with spirits, arms, or tools, the proprietors of the woods engage them to fell a number of trees in proportion to their debts. This is done in the dry season, the rainy period being taken for the shipment of the logs, which are conveyed chiefly to the island of Carmen in the Laguna de Terminos in South-western Yucatan, and to Frontera on the mouths of the Tabasco river, at which places European ships receive cargoes of the wood.

In 1877 the export of Laguna de Terminos amounted to 528,605 quintals (one quintal = 46 kilogrammes), that from Port-au-Prince, Hayti, in 1872, nearly to 90,000 tons.

Four sorts of logwood are found in the London market, namely _Campeachy_, quoted[831] at £8 10_s._ to £9 10_s._ per ton; _Honduras_, £6 10_s._ to £6 15_s._; _St. Domingo_, £5 15_s._ to £6; _Jamaica_, £5 2_s._ 6_d._ to £5 10_s._ The imports into the United Kingdom were valued in 1872 at £233,035. The quantities imported during that and the previous three years were as follows:—

1869 1870 1871 1872 50,458 tons. 62,187 tons. 39,346 tons. 46,039 tons.

[829] Benedikt, in 1875, assigned them the formula C₄₈H₃₉O₁₈N + 9 OH₂.

[830] _Voyage dans l’Amérique centrale, l’île de Cuba et le Yucatan_, Paris, 1857.

[831] _Public Ledger_, 28 Feb. 1874.

In 1876 the import was 64,215 tons, valued at £415,857. The largest quantity is supplied by the British West India Islands. Hamburg also imports annually about 20,000 tons of logwood.

=Uses=—Logwood in the form of decoction is occasionally administered in chronic diarrhœa, and especially in the diarrhœa of children. Cases have occurred in which its use has been followed by phlebitis. Its employment in the art of dyeing is far more important.

=Adulteration=—The woods of several species of _Cæsalpinia_ imported under the name of _Brazil Wood_ and used for dyeing red, bear an external resemblance to logwood, with which it is said they are sometimes mixed in the form of chips. They contain a crystallizable colouring principle called _Brasilin_, C₂₂H₂₀O₇, or, according to Liebermann and Burg (1876), C₁₆H₁₄O₅, which affords with alkalis _red_ and not bluish or purplish solutions, and yields trinitrophenol, C₆H₂(NO₂) 3OH (picric acid), when boiled with nitric acid, while hæmatoxylin yields oxalic acid only. The best source for brasilin is the wood of _Cæsalpinia Sappan_ L., a tree of the East Indies, well known as _Bakam_, _Brazil Wood_, _Lignum Brasile_, _Verzino_ of the Italians, an important object of commerce during the middle ages.[832]

FOLIA SENNÆ.

_Senna Leaves_; F. _Feuilles de Séné_; G. _Sennesblätter_.

=Botanical Origin=—The Senna Leaves of commerce are afforded by two species of _Cassia_[833] belonging to that section of the genus which is distinguished by having leaves without glands, axillary racemes elongating as inflorescence advances, membranaceous bracts which in the young raceme conceal the flower buds but drop off during flowering, and a short, broad, flat legume.

The senna plants are low perennial bushy shrubs, 2 to 4 feet high, having pari-pinnate leaves with leaflets unequal at the base, and yellow flowers. The pods contain 6 or more seeds in each, suspended on alternate valves by long capillary funicles. These run towards the pointed end of the seed, but are curved at their attachment to the hilum just below. The seeds are compressed and of an obovate-cuneate or oblong form, beaked at the narrower end.[834]

The species in question are the following:—

1. _Cassia acutifolia_ Delile[835]—a shrub about 2 feet high, with pale subterate or obtusely angled, erect or ascending branches, occasionally slightly zigzag above, glabrous at least below. Leaves usually 4-5-jugate; leaflets oval or lanceolate, acute, mucronate, usually more or less distinctly puberulous or at length glabrous, pale or subglaucous at least beneath, subsessile. Stipules subulate, spreading or reflexed, 1-2 lines long. Racemes axilliary, erect, rather laxly many-flowered, usually considerably exceeding the subtending leaf. Bracts membranous, ovate or obovate, caducous. Pedicels at length 2-3 lines. Sepals obtuse, membranous. Two of the anterior anthers much exceeding the rest of the fertile stamens. Legume flat, very broadly oblong, but slightly curved upwards, obliquely stipitate, broadly rounded at the extremity with a minute or obsolete mucro indicating the position of the style on the upper edge; 1½-2¼ inches long, ¾-1 inch broad; valves chartaceous, obsoletely or thinly puberulous, faintly transverse-veined, unappendaged. Seeds obovate-cuneate, compressed; cotyledons plane, extending the large diameter of the seed in transverse section.[836]

[832] See Yule, _Marco Polo_, ii. (1874). 369.

[833] Some writers have removed these plants from _Cassia_ to a separate genus named _Senna_, but such subdivision is repudiated by the principal botanists. The intricate synonymy of the senna plants has been well worked out by J. B. Batka in his memoir entitled _Monographie der Cassien-Gruppe Senna_ (Prag, 1866), of which we have made free use. We have also had the advantage of the recent _Revision of the Genus Cassia_ by Bentham (_Linn. Trans._, xxvii. 1871. 503) and of the labours of Oliver on the same subject in his _Flora of Tropical Africa_, ii. (1871) 268-282.

[834] On the structure of the seed, see Batka, _Pharm. Journ._ ix. (1850) 30.

[835] _Synonyms_—_C. Senna_ β. Linn.; _C. lanceolata_ Nectoux; _C. lenitiva_ Bisch.; _Senna acutifolia_ Batka.

[836] We borrow the above description from Prof. Oliver.

The plant is a native of many districts of Nubia (as Sukkot, Mahas, Dongola, Berber), Kordofan and Sennaar; grows also in Timbuktu and Sokoto, and is the source of _Alexandrian Senna_.

2. _C. angustifolia_ Vahl[837]—This species is closely related to the preceding, the general description of which is applicable to it with the following exceptions. In the present plant the leaflets, which are usually 5-8-jugate, are narrower, being oval-lanceolate, tapering from the middle towards the apex; they are larger, being from one to nearly 2 inches long, and are either quite glabrous or furnished with a very scanty pubescence. The legume is narrower (7-8 lines broad), with the base of the style distinctly prominent on its upper edge.

The plant abounds in Yemen and Hadramaut in Southern Arabia; it is also found on the Somali coast, in Sind and the Punjab. In some parts of India it is now cultivated for medicinal use.

The uncultivated plant of Arabia supplies the so-called _Bombay Senna_ of commerce, the true _Senna Mekki_ of the East. The cultivated and more luxuriant plant, raised originally from Arabian seeds, furnishes the _Tinnevelly Senna_ of the drug market.

=History=—According to the elaborate researches of Carl Martius,[838] a knowledge of senna cannot be traced back earlier than the time of the Elder Serapion, who flourished in the 9th or 1Oth century; and it is in fact to the Arabian physicians that the introduction of the drug to Western Europe is due. Isaac Judæus,[839] who wrote probably about A.D. 850-900 and who was a native of Egypt, mentions senna, the best kind of which he says is that brought from Mecca.

Senna (as _Ssinen_ or _Ssenen_) is enumerated among the commodities liable to duty at Acre in Palestine at the close of the 12th century.[840] In France in 1542, a pound of senna was valued in an official tariff[841] at 15 sols, the same price as pepper or ginger.

The Arabian and the mediæval physicians of Europe used both the pods and leaves, preferring however the former. The pods (_Folliculi Sennæ_) are still employed in some countries.

[837] _Synonyms_—_C. lanceolata_ Roxb.; _C. elongata_ Lem. Lis.; _Senna officinalis_ Roxb.; _S. angustifolia_ Batka.

[838] _Versuch einer Monographie der Sennesblätter_, Leipz. 1867.

[839] _Opera Omnia_, Lugd. 1515, lib. 2. Practices, c. 39.

[840] _Recueil des Historiens des Croisades, Lois_, ii. (1843) 177.

[841] Fontanon, _Edicts et Ordonnances des Roys de France_, éd. 2, ii. (1585) 349.

_Cassia obovata_ Coll.[842] was the species first known to botanists, and it was even cultivated in Italy for medicinal use during the first half of the 16th century. Hence the term _Italian Senna_ used by Gerarde and others. In the records of the “Cinque savii alla mercanzia” at Venice we found an order bearing date 1526 to the effect that Senna leaves of Tuscany were inadmissible; the same was applied in 1676 to the drug from Tripoli in Barbaria, that from Cairo being exclusively permitted.

=Production=—According to Nectoux,[843] whose observations relate to Nubia at the close of the last century, the peasants make two senna harvests annually, the first and more abundant being at the termination of the rains,—that is in September; while the other, which in dry seasons is almost _nil_, takes place in April.

The gathering consists in simply cutting down the shrubs, and exposing them on the rocks to the burning sun till completely dry. The drug is then packed in bags made of palm leaves holding about a quintal each, and conveyed by camels to Es-souan and Darao, whence it is transported by water to Cairo. By many travellers it is stated that _Senna jebeli_, i.e. _mountain senna_ (_C. acutifolia_), finds its way to the ports of Massowhah and Suakin, and thence to Cairo and Alexandria.

_Cassia obovata_, which is called by the Arabs _Senna baladi_, i.e. _indigenous_ or _wild senna_, grows in the fields of durra (_Sorghum_) at Karnak and Luxor, and in the time of Nectoux was held in such small esteem that it fetched but a quarter the price of the _Senna jebeli_ brought by the caravans of Nubia and the Bisharrin Arabs. It is not now collected.

=Description=—Three kinds of senna are distinguished in English commerce:—

1. _Alexandrian Senna_—This is furnished by _Cassia acutifolia_ and is imported in large bales. It used formerly always to arrive in a very mixed and dirty state, containing, in addition to leaflets of senna, a variable proportion of leafstalks and broken twigs, pods and flowers; besides which there was almost invariably an accompaniment of the leaves, flowers and fruits of _Solenostemma Argel_ Hayne (p. 220), not to mention seeds, stones, dust and heterogeneous rubbish. Such a drug required sifting, fanning and picking, by which most of these impurities could be separated, leaving only the senna contaminated with leaves of argel. But Alexandrian Senna has of late been shipped of much better quality. Some we have recently seen (1872) was, as taken from the original package, wholly composed of leaflets of _C. acutifolia_ in a well-preserved condition; and even the lower qualities of senna are never now contaminated with argel to the extent that was usual a few years ago.

[842] It is a glaucous shrub with obovate leaflets, broadly rounded and mucronulate, reniform legume terminated by persistent style, and marked along the middle of each valve by a series of crest-shaped ridges corresponding to the seeds. It is more widely distributed in the Nile region than the other species, and is also found in Sindh and Gujerat and (naturalized) in the West Indies. Its leaflets (also pods) may occasionally be picked out of Alexandrian Senna.

[843] _Voyage dans la Haute Egypte ... avec des observations sur les diverses espèces de Séné qui sont répandues dans le commerce_, Paris, 1808. fol.

The leaflets, the general form of which has already been described (p. 216), are ¾ to 1¼ inches long, rather stiff and brittle, generally a little incurled at the edges, conspicuously veined, the midrib being often brown. They are covered with a very short and fine pubescence which is most dense on the midrib. The leaves have a peculiar opaque, light yellowish green hue, a somewhat agreeable tea-like odour, and a mucilaginous, not very marked taste, which however is sickly and nauseous in a watery infusion.

2. _Arabian Moka, Bombay or East Indian Senna_—This drug is derived from _Cassia angustifolia_, and is produced in Southern Arabia. It is shipped from Moka, Aden and other Red Sea ports to Bombay, and thence reaches Europe.

Arabian senna is usually collected and dried without care, and is mostly an inferior commodity, fetching in London sometimes as low a price as ½_d._ to ¼_d._ per lb. Yet so far as we have observed, it is never adulterated, but consists wholly of senna leaflets, often brown and decayed, mixed with flowers, pods, and stalks. The leaflets have the form already described (p. 217); short adpressed hairs are often visible on their under surface.

3. _Tinnevelly Senna_—Derived from the same species as the last, but from the plant cultivated in India, and in a state of far greater luxuriance than it exhibits in the drier regions of Arabia where it grows wild. It is a very superior and carefully collected drug, consisting wholly of the leaflets. These are lanceolate, 1 to 2 inches in length, of a yellowish green on the upper side, of a duller tint on the under, glabrous or thinly pubescent on the under side with short adpressed hairs. The leaflets are less rigid in texture than those of Alexandrian senna, and have a tea-like, rather fragrant smell, with but little taste.

Tinnevelly senna has of late fallen off in size, and some importations in 1873 were not distinguishable from Arabian senna, except from having been more carefully prepared. The drug is generally shipped from Tuticorin in the extreme south of India.

=Chemical Composition=—The analysis of senna with a view to the isolation of its active principle has engaged the attention of numerous chemists, but as yet the results of their labours are not quite satisfactory.

Ludwig (1864) treated an alcoholic extract of senna with charcoal, and obtained from the latter by means of boiling alcohol two bitter principles, _Sennacrol_, soluble in ether, and _Sennapicrin_, not dissolved by ether.

Dragendorff and Kubly (1866) have shown the active substance of senna to be a colloid body, easily soluble in water but not in strong alcohol. When a syrupy aqueous extract of senna is mixed with an equal volume of alcohol, and the mucilage thus thrown down has been removed, the addition of a further quantity of alcohol occasions the fall of a dark brown, almost tasteless, easily alterable substance, which is indued with purgative properties. It was further shown that this precipitate was a mixture of calcium and magnesium salts of phosphoric acid and a peculiar acid. The last named, separated by hydrochloric acid, has been called _Cathartic Acid_; it is a black substance which in the mouth is at first insipid, but afterwards tastes acid and somewhat astringent. In water or strong alcohol it is almost insoluble, and entirely so in ether or chloroform; but it dissolves in warm dilute alcohol. From this solution it is precipitable by many acids, but not by tannic.

Groves[844] in 1868, unaware of the researches of Dragendorff and Kubly, arrived at similar results as these chemists, and proved conclusively that a cathartate of ammonia possesses in a concentrated form the purgative activity of the original drug.

The exactness of the chief facts relative to the solubility in weak alcohol of the active principle of senna set forth by the said chemists, was also remarkably supported by the long practical experience of T. and H. Smith of Edinburgh.[845]

When cathartic acid is boiled with alcohol and hydrochloric acid, it is resolved into sugar and _Cathartogenic Acid_.

The alcoholic solution from which the cathartates have been separated contains a yellow colouring matter which was called _Chrysoretin_ by Bley and Diesel (1849), but identified as _Chrysophan_[846] by Martius, Batka and others. Dragendorff and Kubly regard the identity of the two substances as doubtful.

The same alcoholic solution which contains the yellow colouring matter just described, also holds dissolved a sugar which has been named _Catharto-mannite_. It forms warty crystals, is not susceptible of alcoholic fermentation, and does not reduce alkaline cupric tartrate. The formula assigned to it is C₄₂H₄₄O₃₈.

Senna contains tartaric and oxalic acids with traces of malic acid. The large amount of ash, 9 to 12 per cent., consisting of earthy and alkaline carbonates, also indicates the presence of a considerable quantity of organic acids.

=Commerce=—Alexandrian Senna, the produce of Nubia and the regions further south, was formerly a monopoly of the Egyptian Government, the enjoyment of which was granted to individuals in return for a stipulated payment: hence it was known in continental trade as _Séné de la palte_, while the depots were termed _paltes_ and those who farmed the monopoly _paltiers_.[847] All this has long been abolished, and the trade is now free, the drug being shipped from Alexandria.

Arabian senna is brought into commerce by way of Bombay. The quantity of senna imported thither from the Red Sea and Aden in the year 1871-72 was 4,195 cwt., and the quantity exported during the same period, 2,180 cwt.[848]

=Uses=—Senna leaves are extensively employed in medicine as a purgative.

=Adulteration=—The principal contamination to which senna is at present liable arises from the presence of the leaves of _Solenostemma Argel_ Hayne, a plant of the order _Asclepiadeæ_, 2 to 3 feet high, growing in the arid valleys of Nubia. Whether these leaves are used for the direct purpose of adulteration, or under the notion of _improving_ the drug, or in virtue of some custom or prejudice, is not very evident. It is certain however that druggists have been found who _preferred_ senna that contained a good percentage of argel.

[844] _Pharm. Journ._ x. (1869) 196.

[845] _Ibid._ 315.

[846] See Art. _Radix Rhei_.

[847] From Italian _appaltare_, to let or farm.

[848] _Statement of the Trade and Navigation of the Presidency of Bombay for_ 1871-72, pt. ii. 21. 98.

Nectoux, to whom we owe the first exact account of the argel or hárgel plant,[849] describes it as never gathered with the senna by accident or carelessness, but always separately. In fact he saw, both at Esneh and Phile, the original bales of argel as well as those of senna: and at Boulak near Cairo, at the beginning of the present century, the argel used to be regularly mixed with senna in the proportion of one to four.

The leaves of argel after a little practice are very easily recognized; but their complete separation from senna by hand-picking is a tedious operation. They are lanceolate, equal at the base, of the same size as senna leaflets but often larger, of a pallid, opaque, greyish-green, rigid, thick, rather crumpled, wrinkled and pubescent, not distinctly veined. They have an unmistakeably bitter taste. The small, white, star-like flowers, or more often the flower buds, in dense corymbs are found in plenty in the bales of Alexandrian senna. The slender, pear-shaped follicles, when mature 1½ inches long, with comose seeds are less frequent. It has been shown by Christison[850] that argel leaves administered _per se_ have but a feeble purgative action, though they occasion griping. It is plain therefore that their admixture with senna should be deprecated.

The leaves or leaflets of several other plants were formerly mixed occasionally with senna, as those of the poisonous _Coriaria myrtifolia_ L., a Mediterranean shrub, of _Colutea arborescens_ L., a native of Central and Southern Europe, and of the Egyptian _Tephrosia Apollinea_ Delile. We have never met with any of them.[851]

FRUCTUS CASSIÆ FISTULÆ.

_Cassia Fistula_; _Purging Cassia_; F. _Casse Canefice_, _Fruit du Caneficer_; G. _Röhrencassie_.

=Botanical Origin=—_Cassia Fistula_ L. (_Cathartocarpus Fistula_ Pers., _Bactyrilobium Fistula_ Willd.) a tree indigenous to India, ascending to 4000 feet in the outer Himalaya, but now cultivated or subspontaneous in Egypt, Tropical Africa,[852] the West Indies and Brazil. It is from 20 to 30 feet high (in Jamaica even 50 feet) and bears long pendulous racemes of beautiful fragrant, yellow flowers. Some botanists have established for this tree and its near allies a separate genus, on account of its elongated, cylindrical indehiscent legume, but by most it is retained in the genus _Cassia_.

[849] _Op. cit._ (See p. 218).

[850] _Dispensatory_, ed. 2. 1848. 850.

[851] The reader will find figures of these leaves contrasted with Senna in Pereira’s _Elem. of Mat. Med._ ii.