part 3

; (1878).

=Microscopic Structure=—The chief mass of the tissue is made up of hard, thick-walled, white cells, the groups of which are separated by a brown fibrous prosenchyme. The liber is crossed in a radial direction by numerous broad medullary rays of the usual structure. The parenchymatous portion is loaded both with very large single crystals, and crystalline tufts of calcium oxalate. There is also an abundance of small starch granules, and brown particles of tannic matters. Thin slices of the bark moistened with perchloride of iron, assume a blackish coloration.

=Chemical Composition=—The bitterness and odour of the fresh bark depend no doubt on the presence of a substance analogous to amygdalin, which has not yet been examined. Hydrocyanic acid and essential oil are produced when the bark is distilled with water, and must be due to the mutual action of that substance alluded to, and some principle of the nature of emulsin. From the fact that an extract of the bark remained bitter although the whole of the essential oil and hydrocyanic acid had been removed, Proctor inferred the existence of another substance to which the tonic properties of the bark are perhaps due.

The fresh bark was found by Perot[969] to yield ½ per mille of hydrocyanic acid in April, 1 per mille in June, and 1·4 in October. The best time for collecting the bark is therefore the autumn.

=Uses=—In America, wild cherry bark is held in high estimation for its mildly tonic and sedative properties. It is administered most appropriately in the form of cold infusion or syrup, the latter being a strong cold infusion, sweetened; a fluid extract and a dry resinoid extract are also in use. The bark is said to deteriorate by keeping, and should be preferred when recently dried.

FOLIA LAURO-CERASI.

_Common Laurel or Cherry-laurel Leaves_; F. _Feuilles de Laurier-cerise_; G. _Kirschlorbeerblätter_.

=Botanical Origin=—_Prunus Lauro-cerasus_ L., a handsome evergreen shrub, growing to the height of 18 or more feet, is a native of the Caucasian provinces of Russia (Mingrelia, Imeritia, Guriel), of the valleys of North-western Asia Minor, and Northern Persia. It has been introduced as a plant of ornament into all the more temperate regions of Europe, and flourishes well in England and other parts, where the winter is not severe and the summer not excessively hot and dry.

=History=—Pierre Belon, the French naturalist, who travelled in the East between 1546 and 1550, is stated by Clusius[970] to have discovered the cherry-laurel in the neighbourhood of Trebizond. Thirty years later, Clusius himself obtained the plant through the Imperial ambassador at Constantinople, and distributed it from Vienna to the gardens of Germany. Since it is mentioned by Gerarde[971] as a choice garden shrub, it must have been cultivated in England prior to 1597. Ray,[972] who like Gerarde calls the plant _Cherry-bay_, states that it is not known to possess medicinal properties.

[969] _Pharm. Journ._ xviii (1852) 109.

[970] _Rariorum Plantarum Historia_, 1601. 4.

[971] _Herball_ (1636) 1603.

[972] _Hist. Plant._ ii. (1693) 1549.

In 1731, Madden of Dublin drew the attention of the Royal Society of London[973] to some cases of poisoning that had occurred by the use of a distilled water of the leaves. This water he states had been for many years in frequent use in Ireland among cooks, for flavouring puddings and creams, and also much in vogue with dram drinkers as an addition to brandy, without any ill effects from it having been noticed. The fatal cases thus brought forward occasioned much investigation, but the true nature of the poison was not understood till pointed out by Schrader in 1803 (see art. Amygdalæ amaræ, p. 248, note 2). Cherry-laurel water, though long used on the Continent, has never been much prescribed in Great Britain, and had no place in any British Pharmacopœia till 1839.

=Description=—The leaves are alternate, simple, of leathery texture and shining upper surface, 5 to 6 inches long by 1¾ to 2 inches wide, oblong or slightly obovate, attenuated towards either end. The thick leafstalk, scarcely half an inch in length, is prolonged as a stout midrib to the recurved apex. The margin, which is also recurved, is provided with sharp but very short serratures, and glandular teeth, which become more distant towards the base. The under side, which is of a paler colour and dull surface, is marked by 8 or 10 lateral veins, anastomosing towards the edge. Below the lower of these and close to the midrib, are from two to four shallow depressions or _glands_, which in spring exude a saccharine matter, and soon assume a brownish colour. By the glands with which the teeth of the serratures are provided, a rather resinous substance is secreted.[974]

The fresh leaves are inodorous until they are bruised or torn, when they instantly emit the smell of bitter almond oil and hydrocyanic acid. When chewed they taste rough, aromatic and bitter.

=Microscopic Structure=—The upper surface of the leaf is constituted of thin cuticle and the epidermis made up of large, nearly cubic cells. The middle layer of the interior tissue exhibits densely packed small cells, whereas the prevailing part of the whole tissue is formed of larger, loose cells. Most of them are loaded with chlorophyll; some enclose crystals of oxalate of calcium.

=Chemical Composition=—The leaves when cut to pieces and submitted to distillation with water, yield _Bitter Almond Oil_ and _Hydrocyanic Acid_, produced by the decomposition of _Laurocerasin_. This is an amorphous yellowish substance isolated by Lehmann (1874) in Dragendorff’s laboratory. He extracted the leaves with boiling alcohol, and purified the liquid by gently warming it with hydroxide of lead. From the liquid, crude laurocerasin was precipitated on addition of ether; it was again dissolved repeatedly in alcohol and precipitated by ether. The yield of the leaves is about 1⅓ per cent. Laurocerasin is readily soluble in water, the solution deviates the plane of polarization to the left, yet not to the same amount as amygdalin. The molecule of laurocerasin, C₄₀H₆₇NO₃₀, would appear to include those of amygdalin, C₂₀H₂₇NO₁₁, amygdalic acid, C₂₀H₂₆O₁₂ and 7 OH₂.

[973] _Phil. Trans._ xxxvii. (for 1731-32) 84.

[974] Reinke, in Pringsheim’s _Jahrbücher für wissenschaftliche Botanik_, x. (1875) 129.

The proportion of hydrocyanic acid in the distilled water of the leaves has been the subject of many researches. Among the later are those of Broeker (1867), who distilled a given weight of the leaves grown in Holland under precisely similar circumstances, in each month of the year. The results proved that the product obtained during the winter and early spring was weaker in the acid in the proportion of 17 to 24, 28, or 30, the strongest water being that distilled in July and August. This chemist found that a stronger product was got when the leaves were chopped fine, than when they were used whole. According to Christison,[975] the buds and very young leaves yield ten times as much essential oil as the leaves one year old. We have ascertained that leaves collected in January when they were thoroughly frozen yielded a distillate containing about ten times less of hydrocyanic acid than in summer. The product obtained from the leaves collected in January, but previously dried for several days at 100° C. (212° F.), still proved to contain both essential oil and hydrocyanic acid.

The unwounded leaves of the cherry-laurel in vigorous vegetation have been shown by our friend Prof. Schaer, not to evolve naturally a trace of hydrocyanic acid, though they yield it on the slightest puncture. We are ignorant of the mode of distribution in the living tissue of the laurocerasin, and of the substances causing its decomposition, and how these two bodies are packed so as to prevent the slightest mutual reaction. The leaves may be even dried at 100° C. and powdered without the evolution of any odour of hydrocyanic acid, but the latter is at once developed by the addition of a little water; on distilling its presence is proved by means of all the usual tests in the first drops of the product.

Besides the substances concerned in the production of the essential oil, the leaves contain sugar which reduces cupric oxide in the cold, a small quantity of an iron-greening tannin, and a fatty or waxy substance.

Schoonbroodt (1868) treated the aqueous extract of the fresh leaves with alcoholic ether, which yielded ¼ per mille of bitter, acicular crystals; these quickly reduced cupric oxide, losing their bitterness.

Bougarel (1877) isolated from the leaves under notice and several others, _Phyllinic acid_, a crystalline powder melting at 170° C.

=Uses=—The leaves are only employed for making cherry-laurel water (_Aqua Lauro-cerasi_), the use of which in England is generally superseded by that of the more definite hydrocyanic acid.

FLORES KOSO.

_Flores Brayeræ_, _Cusso_, _Kousso_, _Kosso_.

=Botanical Origin=—_Hagenia abyssinica_ Willd. (_Brayera anthelminthica_ Kunth), a handsome tree growing to a height of 60 feet, found throughout the entire table-land of Abyssinia at an elevation of 3,000 to 8,000 feet above the sea-level.[976] We have never noticed it growing in any botanic garden. The tree[977] is remarkable for its abundant foliage and fine panicles of flowers, and is generally planted about the Abyssinian villages.

[975] _Dispensatory_, 1842. 592.

[976] The French section of the International African Association contributed Kousso from _Madagascar_ to the Paris Exhibition of 1878.

[977] Fig. in Bentley and Trimen, _Med. Plants_,