In Bencoolen[1868] the trees bear all the year round, but the chief harvest takes place in the later months of the year, and a smaller one in April, May and June. The fruit as it splits is gathered by means of a hook attached to a long stick, the pericarp removed, and the mace carefully stripped off. The nuts are then taken to the drying house (a brick building), placed on frames, and exposed to the gentle heat of a smouldering fire, with arrangements for a proper circulation of air. This drying operation lasts for two months, during which time the nutmegs are turned every second or third day. At the end of this period, the kernels are found to rattle in the shell, an indication that the drying is complete. The shells are then broken with a wooden mallet, the nutmegs picked out and sorted, and finally rubbed over with dry sifted lime. In Banda the smaller and less sightly nutmegs are reserved for the preparation of the expressed oil.
The old commercial policy of the Dutch originated the singular practice of breaking the shell, and immersing the kernel of the artificially dried seed in milk of lime,—sometimes for a period of three months. This was done with a view to render impossible the germination of any nutmegs sent into the market. The folly of such a procedure was demonstrated by Teijsmann, who proved that mere exposure to the sun for a week is sufficient to destroy the vitality of the seed. By immersion in milk of lime many nutmegs are spoiled and the necessity is incurred of a second drying. Lumsdaine has also shown that even the dry liming process is, to say the least, entirely needless. Nutmegs are well preserved in their natural shell, in which state the Chinese have the good sense to prefer them.
The process of liming nutmegs is however still largely followed; and the prejudice in favour of the spice thus prepared is so strong in certain countries, that nutmegs not limed abroad have sometimes to be limed in London to fit them for exportation. Penang nutmegs are always imported in the natural state,—that is, un-limed.
Description—The fruit of Myristica fragrans is a pendulous, globose drupe, about 2 inches in diameter, and not unlike a small round pear. It is marked by a furrow which passes round it, and by which at maturity its thick fleshy pericarp splits into two pieces, exhibiting in its interior a single seed, enveloped in a fleshy foliaceous mantle or arillus, of fine crimson hue, which is mace. The dark brown, shining, ovate seed is marked with impressions corresponding to the lobes of the arillus; and on one side, which is of paler hue and slightly flattened, a line indicating the raphe may be observed.
The bony testa does not find its way into European commerce, the so-called nutmeg being merely the kernel or nucleus of the seed. Nutmegs exhibit nearly the form of their outer shell with a corresponding diminution in size. The London dealers esteem them in proportion to their size, the largest, which are about one inch long by ⁸/₁₀ of an inch broad, and four of which will weigh an ounce, fetching the highest price. If not dressed with lime, they are of a greyish brown, smooth yet coarsely furrowed and veined longitudinally, marked on the flatter side with a shallow groove. A transverse section shows that the inner seed-coat (endopleura) penetrates into the albumen in long narrow brown strips, reaching the centre of the seed, thereby imparting the peculiar marbled appearance familiar in a cut nutmeg.
At the base of the albumen and close to the hilum, is the embryo, formed of a short radicle with cup-shaped cotyledons, whose slit and curled edges penetrate into the albumen. The tissue of the seed can be cut with equal facility in any direction. It is extremely oily, and has a delicious aromatic fragrance, with a spicy rather acrid taste.
Microscopic Structure—The testa consists mainly of long, thin, radially arranged, rigid cells, which are closely interlaced and do not exhibit any distinct cavities. The endopleura which forms the adhering coat of the kernel and penetrates into it, consists of soft-walled, red-brown tissue, with small scattered bundles of vessels. In the outer layers the endopleura exhibits small collapsed cells; but the tissue which fills the folds that dip into the interior consists of much larger cells. The tissue of the albumen is formed of soft-walled parenchyme, which is densely filled with conspicuous starch-grains, and with fat, partly crystallized. Among the prismatic crystals of fat, large thick rhombic or six-sided tables may often be observed. With these are associated grains of albuminoid matter, partly crystallized.
Chemical Composition—After starch and albuminoid matter, the principal constituent of nutmeg is the fat, which makes up about a fourth of its weight, and is known in commerce by the incorrect name of Oil of Mace ([see p. 507]).
The volatile oil, to which the smell and taste of nutmegs are chiefly due, amounts to between 3 and 8 per cent.,[1869] and consists, according to Cloëz (1864), almost entirely of a hydrocarbon, C₁₀H₁₆, boiling at 165° C., which Gladstone (1872), who assigns it the same composition, calls Myristicene. The latter chemist found in the crude oil an oxygenated oil, Myristicol, of very difficult purification and possibly subject to change during the process of rectifying. It has a high boiling point (about 220° C.?) and the characteristic odour of nutmeg; unlike carvol with which it is isomeric, it does not form a crystalline compound with hydrosulphuric acid.
Oil of nutmegs, distilled in London by Messrs. Herrings and Co., examined in column 200 mm. long, we found to deviate the ray of polarized light, 15°·3 to the right; that of the Long Nutmeg (Myristica fatua Houtt.), furnished to us by the same firm, deviated 28°·7 to the right.