part 25

(1878).

[748] _Supplement to the Pharmacopœia of India_, Madras, 1869. 16.—The author has kindly sent us specimens of the root. We are also indebted for authentic samples to Mr. Thwaites of the Royal Botanical Garden, Ceylon, and to Mr. Prestoe of the Botanical Garden, Trinidad. The last named gentleman remarks—“I do not find any liquorice property in the root, even fresh, but it is very strong in the green leaves.”

=Microscopic Structure=—On a transverse section the bark exhibits some layers of cork-cells, loaded with brown colouring matter, and then, within the middle zone of the bark, a comparatively thick layer of sclerenchymatous tissue. Strong liber-fibres are scattered through the interior of the cortical tissue, but are not distributed so as to form wedge-shaped rays as met with in liquorice. In the latter the sclerenchyme (thick-walled cells) is wanting. These differences are sufficient to distinguish the two roots.

=Chemical Composition=—The concentrated aqueous infusion of the root of Abrus has a dark brown colour and a somewhat acrid taste accompanied by a faint sweetness. When it is mixed with an alkaline solution of tartrate of copper, red cuprous oxide is deposited after a short time: hence we may infer that the root contains sugar. One drop of hydrochloric or other mineral acid mixed with the infusion produces a very abundant flocculent precipitate, which is soluble in alcohol. If the infusion of Abrus root is mixed with a very little acetic acid, an abundant precipitate is likewise obtained, but is dissolved by an excess. This behaviour is similar to that of glycyrrhizin (see p. 181).

Berzelius observed, so long ago as 1827, that the _leaves_ of Abrus contain a sweet principle similar to that of liquorice.

=Uses=—The root has been used in the place of liquorice, for which it is in our opinion a very bad substitute.

SETÆ MUCUNÆ.

_Dolichi pubes vel setæ_; _Cowhage_, _Cow-itch_[749]; F. _Pois à gratter_, _Pois pouillieux_; G. _Juckborsten_.

=Botanical Origin=—_Mucuna pruriens_ DC. (_Dolichos pruriens_ L., _Stizolobium pruriens_ Pers., _Mucuna prurita_ Hook.), a lofty climbing plant[750] with large, dark purple papilionaceous flowers, and downy legumes in size and shape not unlike those of a sweet pea, common throughout the tropical regions of both Africa, India and America.

=History=—The earliest notice we have found of this plant is that of Parkinson, who in his _Theater of Plants_, published in 1640, names it “_Phaseolus siliquâ hirsutâ_, the Hairy Kidney-Beane called in Zurrate [Surat] where it groweth, _Couhage_” It was subsequently described by Ray (1686), who saw the plant raised from West Indian seeds, in the garden of the Hatton family in Holborn.[751] Rheede figured it in the _Hortus Malabaricus_,[752] and it was also known to Rumphius and the other older botanists. We find it even in the pharmaceutical tariff of the county of Nürnberg, A.D. 1714.[753]

[749] These names and the following are also applied to the entire pods, or even to the plant.

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