Origin.—J. Ch. Sawer reviews the opinions expressed by different botanists as to the origin of commercial vanilla, which seems to be derived from several varieties of perhaps several species, and inclines to Morren's views ("Bull. Acad. Roy. Belg.," 1 ser., xvii, p. 130), that the question can only be solved by an experienced naturalist who should examine the plants in the localities where they actually grow, compare the different length, thickness, shape, color, flavor and value of the fruit yielded by each species and variety, and accompany the diagnoses made by drawings on the spot. The finest commercial vanilla is found by Morren to closely resemble the fruit of Vanilla planifolia, Andrews.
Cultivation.—From Jaillet's report to the Societe d'Emulation ("Rep. Phar.," 1880, p. 357) we quote the following condensed account of the cultivation and preparation of vanilla.
In Mexico vanilla plantations are established in forests by cutting down all shrubs, climbers and large trees as would give an excess of shade, leaving only young trees, preferably those containing a milky sap, to serve as supports to the plants. Close to each tree two cuttings are planted side by side in a shallow trench about 1 ½ inch deep and 15 or 20 inches long, three joints of the cuttings, after the removal of the leaves, being covered up with dried leaves, leaf mould, coarse sand, brush wood, etc., and the remainder of the shoot, 3 or four feet long, tied to the tree. The bed should be slightly raised above the level of the soil, and the supporting trees should be quite 12 to 15 feet apart. The cuttings will have taken root after a month, must be kept free from weeds and underwood, and will commence to bear fruit in the third year. For establishing vanilla plantations in a field, the land is thoroughly ploughed, and sowed with maize; and, while this is growing, young lactescent trees of the fig tribe make their appearance, and after a year are large enough for supporting the vanilla plants, from which the finest product is obtained. The fecundation of the flower is left to nature, and the plant is allowed to climb up over the trees.
In the Island of Reunion (Bourbon) the fecundation is performed artificially, and the plant is not allowed to grow out of the reach of the cultivator, but is guided along trelises formed by sticks, connecting the trunks of the trees together transversely. For supports of the vanilla in plantations established in the open field, mangoes, fig trees, or preferably physic nut trees (Jatropha curcas), are first grown, and the cuttings are set in trenches 8 inches deep, dug between the trees and near the trelises.
Fecundation.—As the labellum totally covers the stigma, and the anther rests on the labellum, spontaneous fecundation is comparatively rare, and even in Mexico, Guiana and other countries, where the plant is left to itself, it has been observed that a length of 12 to 26 inches of vine will produce only one pod from about 40 flowers, all of which can be artificially fecundated. This was formerly performed by cutting the labellum, but is now more successfully done by the method of a Creole slave in the colony, by slipping away the labellum from beneath the anther, and thus bringing that organ in direct contact with the stigma. To prevent injury to the plant by excessive fecundation, only 5 or 6 of the finest flowers on each bunch having a large fleshy peduncle, are fecundated, and when this is assured from the persistence of the flowers and their drying at the extremity of the fruit, the remainder of the bunch with all its buds should be cut off. The handsomest fruits are obtained from the first flowers, but the best from the last flowers which open on each bunch.
Harvesting.—The fecundated flowers decay at the extremity of the ovary, leaving the persistent gynostem attached to the fruit, which continues to grow for a month, but must be left on the stem for six months longer to allow it to ripen. Each pod should be cut off separately as it matures. The only certain indication of maturity is the crackling produced on pinching the pod between the fingers; the apple-green or greenish-yellow color is not a sufficient sign. If unripe the product will lack fragrance, color, etc.; if over-ripe, it is apt to become split in curing.
Curing of the Fruit.—The odor of vanilla does not pre-exist in the ripe fruit, but is developed by a process of fermentation. If allowed to remain on the plant, the pod splits into two unequal parts, becoming yellow, brown, and finally black. While it is drying it exudes an unctuous liquid, of a dark red color, called balsam of vanilla, and when quite dry becomes brittle and devoid of perfume.
The curing is effected in Guiana by placing the pods in ashes until they begin to shrivel, when they are wiped, rubbed over with olive oil and, their lower end having been tied, are hung in the open air to-dry.
In Peru the pods are dipped into boiling water, tied at the end and hung in the open air for 20 days to dry; they are then lightly smeared over with oil of palma christi, and a few days later are tied in bundles.
In Mexico the pods are placed in heaps under a shed, protected from sun and rain, and in a few days, when they begin to shrivel, are submitted to the sweating process. If the weather happens to be warm and fine, the pods are spread out in the early morning on a woolen blanket, and exposed to the direct rays of the sun, but about mid-day are wrapped in the blanket. In the evening they are enclosed in airtight boxes for sweating during the night, and on the next day they are again exposed to the sun, the dark coffee color which they acquire being deeper in proportion to the success of the sweating operation. In cloudy weather the vanilla is made into bundles; a number of these are packed together into a small bale, which is first wrapped in a woolen cloth, then in a coating of banana leaves, and the whole, enclosed in a mat, is firmly bound and sprinkled with water. The bales containing the largest beans are now placed in an oven heated to 140°F. When the temperature of the oven has fallen to 113°F., the smaller beans are introduced and the oven is closed tightly. Twenty-four hours afterwards the smaller beans were taken out, and twelve hours later the larger ones. During the sweating the vanilla acquires a fine chestnut color. It is now spread on matting, exposed to the sun every day for about two months, and when the drying is nearly complete is spread out in a dry place, and finally tied up in small packets.
In Reunion the pods are sorted according to length and scalded in water of 194°F., the long ones for 10 seconds, and the medium and short ones for 15 seconds and one minute. They are then exposed for 6 or 8 days to the sun, between woolen blankets, until they acquire the characteristic chestnut color, when they are spread out, under sheds roofed with zinc, to dry gradually for about a month, being frequently turned in the meantime. When they have acquired the proper degree of dryness to be easily twisted around the finger without cracking, they undergo the smoothing process, each bean being repeatedly passed by the operator between his fingers; the oil exuded from the entire surface of the bean imparts the lustre and suppleness. When sufficiently dry, the beans are tied up in bundles of uniform length. The three commercial varieties are, 1, fine vanilla, 8 to 11 inches long, nearly black, unctuous, glossy and clean-looking, and soon becoming covered with frost-like crystals; 2, woody vanilla, 6 to 8 inches long, lighter in color, more or less spotted with grey, not glossy, with few crystals; collected in an unripe condition; 3, vanillons, either obtained from short ripe fruit, frosting well, or the abortive and unripe fruit, whose perfume is simply the result of absorption from the fine beans with which they have so long been in contact.
The total yield of the Mauritius and Reunion plantations is estimated at 29,255 kilos in 1875, 34,322 kilos in J876, 41,270 kilos in 1877, 35,000 kilos in 1878 and 40,000 kilos in 1880.
Vanillin.—Its amount in commercial vanilla from various sources has been estimated at from 1.5 to 2.5 per cent. The benzoic acid found by some chemists in Mexican vanilla was, according to Tiemann and Haarmann, a mixture of vanillic acid and its aldehyd vanillin; or benzoic acid may have been dusted over inferior qualities of vanilla to imitate the natural inflorescence. Although vanillin is the principal vehicle of the aroma, it is believed not to constitute the sole flavor and perfume of vanilla, and that the vanillin prepared artificially by Tiemann and Haarmann will not quite discourage the Mexican and Bourbon planters.
Vanillon.—The odor of East Indian vanillon more resembles heliotrope, probably owing to a trace of benzoic aldehyd. Tiemann and Haarmann found the vanillin to amount only to 0.4 per cent., and to be more difficult to isolate by reason of the presence of a minute quantity of oily matter, which adheres to it with great tenacity.
Products having a Vanilla-like Odor.—The "wild vanilla" of North America is Liatris odoratissima, Willd.; the odor of the leaves resembles that of vanilla and tonka. For description, use, etc., see "Amer. Jour. Phar." 1859, p. 566; 1866, p. 443; 1874, p. 299, and 1875, p.116.
The dried leaves and fruit of Angraecum (s. Aerobion, Sprengel; Aeranthus, Reichenbach) fragrans, Du Petit-Thouars, which is known in Reunion and Mauritius as "faham," and in Madagascar as "fanave," possess an agreeable odor, resembling a mixture of vanilla, tonka and melilot. The aromatic principle of the leaves is soluble in alcohol, ether and boiling water; it has been isolated by Gobley ("Jour. de Phar.": xvii, p. 350) in the form of small white silky needles, which, on being pressed between the fingers or slightly warmed, develop the characteristic odor of "faham" and bitter almonds. It was found to contain C 76.12, H 4.12 and O 19.76, approximating it to the composition of coumarin. The fruit is supposed to contain a larger proportion of this principle than the leaves. The plant is propagated by seed. An infusion of the leaves is taken as a beverage; the mucilaginous and bitter properties contained in them are considered to act as a digestive and as a remedy for pulmonary consumption, and the dried leaves when smoked as beneficial in cases of asthma (see also this Journal, page 339). A somewhat similar odoriferous principle has been found in the leaves of other orchideous plants, as the Orchis fusca, and the Ophris antropophora, but not identical with vanillin.— Pharm. Jour. and Trans., March 18, 1881, pp. 773-775.