rare and costly. It has long been obsolete in all countries except Holland, where until recently it was to be met with in the shops. The Pharmacopaa Neerlandica of 1851 says of it "Origo botanica perquam dubia.-Patria Malacca ?"

Description-The specimen of the root of Toddalia aculeata which we have examined was collected for us by Dr. G. Bidie of Madras whose statements regarding the stimulant and tonic action of the drug may be found in the Pharmacopoeia of India, p. 442. It is a dense woody root in cylindrical, flexuous pieces, which have evidently been of considerable length and are from to 1 inches in diameter, covered with bark to

of an inch in thickness. The bark has a soft, dull yellowish, suberous coat, wrinkled longitudinally, beneath which is a very thin layer of a bright yellow colour, and still lower and constituting twothirds or more of the whole, is the firm, brown middle cortical layer and liber which is the part chiefly possessing the characteristic pungency and bitterness of the drug. The yellow corky coat is however not devoid of bitterness. The wood is hard, of a pale yellow, and without taste and smell. The pores of the wood which are rather large, are arranged in concentric order and traversed by numerous narrow medullary

rays.

2

In a letter which Frappier wrote to Guibourt from the island of Réunion where Toddalia aculeata is very common, he states that the roots of the plant are of enormous length (longueur incroyable) and rather difficult to get out of the basaltic rock into the fissures of which they penetrate. Mr. J. Horne of the Botanical Garden, Mauritius, has sent us a specimen of the root of this plant, the bark of which is of a dusky brown, with the suberous layer but little developed.

Microscopic Structure-We have examined the root for which we are indebted to Dr. Bidie, and may state that its cortical tissue is remarkable by the number of large cells filled with resin and essential oil; they are scattered through the whole tissue, the cork excepted. The parenchymatous cells are loaded with small starch granules or with crystals of oxalate of calcium. The vessels of younger roots abound in yellow resin.

Chemical Composition-None of the constituents of the Toddalia root of India have yet been satisfactorily examined. The bark contains an essential oil, which would be better extracted from fresh than from dry material. The tissue of the bark is but little coloured by salts of iron. In the aqueous infusion, tannic acid produces an abundant precipitate, probably of an indifferent bitter principle rather than of an alkaloid. We have been unable to detect the presence in the bark of berberine.

Lopez root was examined in Wittstein's laboratory by Schnitzer who found that the bark contains in addition to the usual substances a large proportion of resin,-a mixture probably of two or three different bodies. The essential oil afforded by the bark had an odour resembling cinnamon and melissa.

1 Our friend Dr. de Vry informs us that he remembers the price in Holland in 1828 being equivalent to about 24s. the ounce! 2 Journ. de Pharm. v. (1867) 403.

3 Wittstein's Vierteljahresschrift für prakt. Pharm. xi. (1862) i.-The drug examined was the Lopez root sold at that period at Amsterdam.

Uses-The drug has been introduced into the Pharmacopoeia of India chiefly upon the recommendation of Dr. Bidie of Madras, who considers it of great value as a stimulating tonic. The bark rasped or shaved from the woody root is the only part that should be used.

AURANTIACEÆ.

FRUCTUS LIMONIS.

Lemon; F. Citron, Limon; G. Citrone, Limone.

Botanical Origin-Citrus Limonum Risso (C. medica var. B Linn.), a small tree 10 to 15 feet in height, planted here and there in gardens in many sub-tropical countries, but cultivated as an object of industry on the Mediterranean coast between Nice and Genoa, in Calabria, Sicily, Spain and Portugal.

The tree which is supposed to represent the wild state of the lemon and lime, and as it seems to us after the examination of numerous specimens in the herbarium of Kew, of the citron (Citrus medica Risso) also, is a native of the forests of Northern India, where it occurs in the valleys of Kumaon and Sikkim.

The cultivated lemon-tree is of rather irregular growth, with foliage somewhat pallid, sparse, and uneven, not forming the fine, close head of deep green that is so striking in the orange-tree. The young shoots are of a dull purple; the flowers, which are produced all the year except during the winter and are in part hermaphrodite and in part unisexual, have the corolla externally purplish, internally white, and a delicate aroma distinct from that of orange blossom. The fruit is pale yellow, ovoid, usually crowned by a nipple.

History-The name of the lemon in Sanskrit is Nimbuka; in Hindustani, Limbu, Limu, or Ninbu. From these sounds the Arabians formed the word Limun, which has passed into the languages of Europe.

The lemon was unknown to the inhabitants of ancient Greece and Rome; but it is mentioned in the Book of Nabathæan Agriculture,1 which is supposed to date from the 3rd or 4th century of our era. The introduction of the tree to Europe is due to the Arabians, yet at what precise period is somewhat doubtful. The geographer Edrisi, who resided at the court of Roger II., king of Sicily, in the middle of the 12th century, mentions the lemon (limouna) as a very sour fruit of the size of an apple which was one of the productions of Mansouria on the Mahrân or Indus; and he speaks of it in a manner that leads one to infer it was not then known in Europe. This is the more probable from the fact that there is no mention either of lemon or orange in a letter written A.D. 1239 concerning the cultivation of the lands of the Emperor Frederick II. at Palermo, a locality in which these fruits are now produced in large quantity.

On the other hand the lemon is noticed at great length by Ibn Baytar of Malaga who flourished in the first half of the 13th century, but of its cultivation in Spain at that period there is no actual mention.* 1 Meyer, Geschichte der Botanik, iii. (1856)

68.

2 Géographie d'Edrisi, traduite par Jaubert, i. (1836) 162.

3 Huillard-Bréholles, Historia diplomatica Friderici secundi, Paris, v. 571.

4 Heil- und Nahrungsmittel von Ebn Baithar, übersetzt von Sontheimer, ii. (1842) 452.

There is distinct evidence that the tree was grown on the Riviera of Genoa about the middle of the 15th century, since Limones and also Citri are mentioned in the manuscript Livre d'Administration of the city of Savona, under date 1468.1 The lemon was cultivated as early as 1494 in the Azores, whence the fruit used to be largely shipped to England; but since the year 1838 the exportation has totally ceased.2

Description-The fruit of Citrus Limonum as found in the shops 3 is from about 2 to 4 inches in length, egg-shaped with a nipple more or less prominent at the apex; its surface of a pale yellow, is even or rugged, covered with a polished epidermis. The parenchyme within the latter abounds in large cells filled with fragrant essential oil. The roughness of the surface of the rind is due to the oil-cells. The peel which varies considerably in thickness but is never so thick as that of the citron, is internally white and fibrous, and is adherent to the paleyellow pulp. The latter is divided into 10 or 12 segments each containing 2 or 3 seeds. It abounds in a pale-yellow acid juice having a pleasant sour taste and a slight peculiar odour quite distinct from that of the peel. When removed from the pulp by pressure, the juice appears as a rather turbid yellowish fluid having a sp. gr. which varies from 1.040 to 1.045, and containing in each fluid ounce from 40 to 46 grains of citric acid, or about 9 per cent. Lemon juice (Succus limonis) for administration as a medicine should be pressed as wanted from the recent fruit whenever the latter is obtainable.

The peel (Cortex limonis) cut in somewhat thin ribbons from the fresh fruit is used in pharmacy and is far preferable to that sold in a dried state.

Microscopic Structure of the peel. The epidermis exhibits numerous stomata; the parenchyme of the pericarp encloses large oilcells, surrounded by small tabular cells. The inner spongy tissue is built up of very remarkable branched cells, separated by large intercellular spaces. A solution of iodine in iodide of potassium imparts to the cell-walls a transient blue coloration. The outer layers of the parenchymatous tissue contain numerous yellowish lumps of a substance which assumes a brownish hue by iodine and yields a yellow solution if potash be added. Alkaline tartrate of copper is reduced by this substance, which probably consists of hesperidin. There also occur large crystals of oxalate of calcium, belonging to the monoclinic system. The interior tissue is irregularly traversed by small vascular bundles.

Chemical Composition-The peel of the lemon abounds in essential oil which is a distinct article of commerce, and will be described hereafter.

Lemons as well as other fruits of the genus Citrus contain a bitter principle, Hesperidin, our knowledge of which is still very imperfect. It was first obtained in 1827 by Lebreton, but not in a state of purity. He supposed the bitter taste of the needle-shaped crystals of his hesperidin to be due to an accompanying bitter principle; Lepage likewise stated hesperidin to be a tasteless body. Dehn in 1866 examined the products of decomposition of hesperidin, which were formed by boiling 1 Gallesio, Traité du Citrus (1811) 89, 105.

2 Consul Smallwood, in Consular Reports, Aug. 1873. 986.

There are many kinds of lemon as well

as of orange which are never seen in commerce. Risso and Poiteau enumerate 25 varieties of the former and 30 of the latter. 4 Stoddart, in Pharm. Journ. x. (1869) 203.

it with dilute sulphuric acid. He analysed the peculiar sugar, C12H24010+ H2O, thus obtained, but not the other product of this reaction, nor hesperidin itself.

Brandes in 1841 also pointed out the existence of a bitter principle, to which he applied the name of Aurantiin. In 1840 Bernays obtained Limonin from kernels of lemons or sweet oranges, likewise a bitter principle, to which Schmidt (1844) assigned the formula C44H52014. Lastly, J. E. de Vry in 1866 removed a crystallized bitter substance from the flowers of Citrus decumana L. grown in Java.

Whether these bodies are but one and the same is a question which remains to be investigated. Lebreton's hesperidin is soluble in ammonia with a greenish yellow colour. To it perhaps is due the fine yellow tint that is produced in the white parenchyme of the fruit when brought into contact with an alkali or with vapour of ammonia.

On addition of ferric chloride, thin slices of the peel are darkened, owing probably to a kind of tannic matter.

Lemon juice, some of the characters of which have been already noticed, is an important article in a dietetic point of view, being largely consumed on shipboard for the prevention of scurvy. In addition to citric acid it contains 3 to 4 per cent. of gum and sugar, and 2.28 per cent. of inorganic salts, of which according to Stoddart only a minute proportion is potash. Cossa on the other hand who has recently studied the products of the lemon tree with much care, has found that the ash of dried lemon juice contains 54 per cent. of potash, besides 15 per cent. of phosphoric acid.

Stoddart has pointed out the remarkable tendency of citric acid to undergo decomposition, and has proved that in lemons kept from February to July this acid generally decreases in quantity, at first slowly but afterwards rapidly, until at the end of the period it entirely ceases to exist, having been all split up into glucose and carbonic acid. At the same time the sp. gr. of the juice was found to have undergone but slight diminution:—thus it was 1.044 in February, 1.041 in May, and 1·027 in July, and the fruit had hardly altered in appearance. Lemon juice may with some precautions be kept unimpaired for months or even years. Yet it is capable of undergoing fermentation by reason of the sugar, gum, and albuminoid matters which it contains.

Commerce-Lemons are chiefly imported from Sicily, to a smaller extent from the Riviera of Genoa and from Spain. From the published statistics of trade, in which lemons are classed together with oranges under one head, it appears that these fruits are being imported in increasing quantities. The value of the shipments to the United Kingdom in 1872 (largely exceeding those of any previous year) was £1,154,279. Of this sum, £986,796 represents the value of the oranges and lemons imported from Spain, Portugal, the Canary Islands and Azores; £155,330 the shipments of the same fruit from Italy; and £3,825 those from Malta.

Uses-Lemon peel is used in medicine solely as a flavouring ingredient. Freshly prepared lemon juice is often administered with

1 Gazzetta Chimica Italiana, ii. (1872) 385; Journ. of Chem. Soc. xi. (1873) 402.

Stoddart's statement that if potash be

added to lemon juice, oxalic acid may be detected in the mixture after a few days, is not supported by our observations.

an alkaline bicarbonate in the form of an effervescing draught, or in a free state.

Concentrated lemon juice or lime juice is imported for the purpose of making citric acid; it is derived not only from the lemon, but also from the lime and bergamot.

OLEUM LIMONIS.

Oleum Limonum; Essential Oil or Essence of Lemon; F. Essence de Citron; G. Citronenöl.

Botanical Origin-Citrus Limonum Risso (see p. 103).

History-The chemists of the 16th century were well acquainted with the method of extracting essential oils by distillation. Besson in his work L'art et moyen parfaict de tirer huyles et eaux de tous medicaments simples et oleogineux published at Paris in 1571, mentions lemon(citron) and orange-peel among the substances subjected to this process. Giovanni Battista Porta, a learned Neapolitan writer, describes the method of preparing Oleum ex corticibus Citri to consist in removing the peel of the fruit with a rasp and distilling it so comminuted with water; and adds that the oils of lemon and orange may be obtained in the same manner. Essence of lemon of two kinds, namely expressed and distilled, was sold in Paris in the time of Pomet, 1692.

Production-Essential oil of lemon is manufactured in Sicily, at Reggio in Calabria, and at Mentone and Nice in France.

The lemons are used while still rather green and unripe, as being richer in oil than when quite mature. Only the small and irregular fruit such as is not worth exporting, is employed for affording the essence.

The process followed in Sicily and Calabria may be thus described; 2 it is performed in the months of November and December.

The workman first cuts off the peel in three thick longitudinal slices, leaving the central pulp of a three-cornered shape with a little peel at either end. This central pulp he cuts transversely in the middle, throwing it on one side and the pieces of peel on the other. The latter are allowed to remain till the next day and are then treated thus:-the workman seated holds in the palm of his left hand a flattish piece of sponge, wrapping it round his fore-finger. With the other he places on the sponge one of the slices of peel, the outer surface downwards, and then presses the zest-side (which is uppermost) so as to give it for the

moment a convex instead of a concave form. The vesicles are thus ruptured, and the oil which issues from them is received in the sponge with which they are in contact. Four or five squeezes are all the workman gives to each slice of peel, which done he throws it aside. Though each bit of peel has attached to it a small portion of pulp, the workman contrives to avoid pressing the latter. As the sponge gets saturated the workman wrings it forcibly, receiving its contents in a coarse earthen

1 Magic Naturalis libri xx. Neapoli,

1589. 183.

Through the kindness of Signor Mallandrino of Giam pilieri near Messina, I had the pleasure of seeing how the essence is made. Though the time of my visit

(13 May 1872) was not that of the manufacture, Signor M. sent for one of his workmen, and having procured a few lemons, set him to work on them in order that I might have ocular demonstration of the process.-D. H.