95 



back of the throat is also observed. All part of the plant — leaves, stem, and 

 root — possess this property, but the leaves and root appear to act more power- 

 fully than the stem; the leaves have an aromatic taste due to an essential oil 

 which is absent from the root. 



The following is a brief botanical description of Piper ovalum, taken partly 

 from Grisebach and partly from our own observations. 



Shrub, 2 — 4 feet high ; root woody, spreading. Stems erect, slender, some- 

 what woody, branching in zig-zags, nodes tumid ; leaves alternate, 3 — 6 inches 

 long, 2 — 3 inches broad, ovate, pointed, l>roadly cuneate at base, papery opaque, 

 glabrous ; petiole channelled, naked, about |— | inch long. Flowers usually 

 racemose, pedicles jointed with the flower. Bracts cucullate, usually at the 

 base of a pedicel ; stamens 4( — 3) inserted round the ovary ; stigmas 4, sessile. 

 Pericarp baccate, tetragonal. Berries pedicellate, somewhat longer than their 

 pedicel, rounded at base, mucronate with a bluntish point. Habitat, Trinidad. 



A number of the living plants have been brought to England, in Wardian 

 cases, and are at present growing at Kew Gardens, but so far they have shown no 

 signs of flowering. 



Volatile Constituents. 



As the aromatic taste of the leaves suggested the probability of the presence 

 of a volatile oil, the leaves were distilled with steam in the usual manner and 

 the distillate extracted with ether. By this means a small quantity of an almost 

 colourless, volatile, aromatic oil was obtained which was non-alkalo'idal and did 

 not produce any tingling of the tongue. When cooled below 0° and stirred, the 

 oil showed no tendency to solidify. Its density was 15°/15°=0*9904. It boiled 

 at about 245°, nearly the whole passing over between 240'' and 250°. It appears 

 to be optically inactive, since a 6 per cent, solution in alcohol produced no 

 rotation of the polarised ray. When dry hydrogen chloride was led into a dry 

 ethereal solution of the oil, there was no separation of crystals, even after the 

 liquid had been cooled to — 13°. When a drop of the oil was dissolved in 

 chloroform and strong sulphuric acid added, an intense crimson coloration was 

 produced, passing into a I'eddish-violet. Aqueous alkalis did not act on the oil, 

 and it formed no compound with sodium hydrogen sulphite. We have not had 

 sufficient of the substance for analysis, but from the properties recorded above 

 the volatUe oil of Piper ovatum would appear to be a sesquiterpene. The leaves 

 contain this oil to the largest extent, little or none being present in the root 

 or stem. 



Non-volatile Constituents. 



The liquid remaining with the leaves after distilling off the oil w ith steam, 

 though highly coloured, had none of the activity of the leaves themselves, and 

 gave rise to little or no tingling when tasted ; it was, therefore, clear that the 

 active constituent was not appreciably soluble in water. This aqueous .solution 

 contained no alkaloid, but a sugar having cupric reducing power was present, 

 and also a considerable quantity of potasnium nitrate. The leaves having been 

 drained from the water were digested for some hours with boiling alcohol (50 per 

 cent.), the process being repeated until they had lost nearly all their tingling 

 property. The green alcoholic solution, which was highly active, was evaporated 

 to dryness, the residue extracted with absolute alcohol, and the alcoholic solution 

 fractionally precipitated by the addition of small quantities of water aided by 

 the evaporation of some of the alcohol. The first precipitate contained nearly 

 the wliole of the chlorophyll, but scarcely any of the active constituent. The 

 second precipitate also contained chlorophyll, but was active although not nearly 

 so strongly as the filtrate ; this second precipitate was, therefore, dissolved 

 in alcohol and reprecipitated by water, the filtrate being added to the original 

 filtrate, and the whole evaporated until the alcohol had been dissipated. The 

 aqueous solution was then extracted by shaking with ether which removed tiie 

 active constituent together with colouring matter. The residue left on evapo- 

 rating the ether was dissolved in alcohol, and the solution fractionally precipitated 

 with water, this process being repeated until the whole of the green colouring 

 matter had been removed. Ether then extracted from the liquid, after the 

 evaporation of the alcohol, a light brown resin which was highly active in 

 inducing tingling of the tongue and showed no signs of crystallisation even after 

 prolonged standing. 



