372 INDIAN MEDICINAL PLANTS.
ceolate, long, acuminate, entire, thinly coriaceous, usually quite
glabrous, lateral nerves 8-15 pair, alternating with shorter in-
termediate ones ; base rounded acute or oblique, petiolules
slender, 1/5-2/5in. long. Panicles axillary, with slender and
drooping ramifications, much shorter than the leaves. Flowers
pedicelled, scarcely 1/10in. diam., greenish yellow. Sepals
ovate-obtuse. Petals much larger, oblong or obtuse. Disk
5-lobed. Drupes ¼in. diam., compressed, glabrous, rugose,
yellow or light brown; epicarp thin, bursting irregularly.
Mesocarp fibrous. Kernel compressed, hard, surrounded by
a vegetable wax (Kanjilal), " mixed with the fibre," adds
Brandis.
Use : — The juice of the leaves is said to blister the skin (Stewart). The fruit is considered officinal and is used in Kash- mir in the treatment of phthisis.
Chemistry.— The sap is a thick, nearly white, alkaline cream, superficially oxidisable by air to an intensely black, impervious susbtance, insoluble in the usual solvents.
Complete oxidation only takes place in the presence of a diastatic ferment, laccase, which can be separated from the other essential constituent of the sap by means of alcohol, in which it is insoluble. When precipitated by alcohol from aqueous solution, the crude laccase dries to white, opaque fragments, like gum, and is probably a mixture of the ferment with carbo-hydrates, as it can be oxidised to mucic acid, and hydrolysed to galactose and arabinose.
From the portion of the sap soluble in alcohol, a substance, laccol, probably a polyphenol, can be precipitated by lead acetate. It is a thick oil, insoluble in water, but soluble in alcohol, &c, and is intensely irritating to the skin, as is the crude sap. Laccol is readily oxidisable in the air to a reddish, viscous, or resinous substance ; in alkaline solution, it behaves like pyrogallol, blackening and absorbing oxygen with such rapidity as to become hot ; it reduces ferric chloride in alcoholic solution, forming a black, metallic derivative.
When laccol is precipitated from alcoholic solution by an aqueous solution of laccase, the white emulsion rapidly blackens from absorption of oxygen ; but this does not take place if the laccase solution has been boiled, or if water alone is the precipitant. The action of laccase on gallic acid &C, is similar, the rate of absorption of oxygen being enormously increased. As the ferment has no action on starch, sugar, amygdalin, &c, it seems to be the first member of a new class of " oxidising diastases."
Since laccase is present in many plants, it seems not improbable that this diastase plays an important part in the respiration of plants,
J.Ch.S. 1895 A l p. 386.
