Divi-divi, or Libi-dibi.—These names are applied to the seed-pods of Cæsalpinia coriaria, a tree of 20-30 ft., indigenous to several of the West Indies, Mexico, Venezuela, and North Brazil, and naturalised in Madras and Bombay Presidencies, and in the North-West Provinces. The pod may be known by its drying to the shape of a letter S; it contains 30-50 per cent. of a peculiar tannin, somewhat similar to that of valonia. It is cheap, and may be used in admixture with barks; but it is dangerously liable to undergo fermentation, suddenly staining the leather a dark-red colour, and is therefore not in extensive use. The imports of it are mainly from Maracaibo, Paraiba, and St. Domingo. Maracaibo, in 1880, exported 197,674 lb. of divi-divi, value 32221/4 dol. (4s. 2d.), to New York. Our imports of divi-divi into Liverpool, according to figures kindly furnished by Haw & Co., were 2200 tons in 1877, 1740 in 1878, 2132 in 1879, and 780 in 1880. The approximate market value is 12-17l. a ton.
Galls.—The generic term "gall" is applied to those excrescences on plants which are produced by the punctures of insects, for the purpose of depositing their eggs. The excrescences are usually considered to be a diseased condition of vegetable tissue, resulting from the injection of some secretion of the insects. But this has been combated by A. S. Wilson, of Aberdeen, who considers that all insect galls are in reality leaf-buds, or fruit-buds, and not mere amorphous excrescences. The vascular lines which would form leaves can easily be followed up in the structure of the oak-leaf galls. And in cases where the egg has been deposited in the tissue of a young branch, the cap of the gall is sometimes surmounted by a leaf 2-3 in. long. But in the large blue Turkish galls, many lacunæ occur where the fleshified leaves have not filled up the spaces between them. If a dissection be made of one of the weevil-galls on the bulb of the turnip, the second or third slice will show the outer foliations, exactly similar to those of the root-buds. When the centre has been reached, where the maggot will be found, there will also be a vascular pencil running up from a medullary ray in the bulb, and bearing on its top a bud of the same description as that produced by a ray running out from a root. The insertion of the ovipositor brings a medullary ray into action, producing a tuberculated bud, and it is only the bud which the larva feeds upon. The growth of a bud is an intelligible cause of the growth of a gall, but nothing can be inferred from the injection of a fluid. The analogy to leaves is further shown by the fact that various microscopic fungi are matured in the interior of imperforate galls.
The principal commercial kinds of gall are oak-galls and Chinese galls.
Oak-galls, Nut-galls, Aleppo or Turkey-galls (Fr., Noix de Galle, Galle d'Alep; Ger., Levantische or Aleppische Gallen, Galläpfel).—These are formed by the punctures of Cynips [Diplolepis] Gallæ tinctoriæ on Quercus lusitanica var. infectoria [Q. infectoria], a shrubby tree of Greece, Cyprus, Asia Minor, and Syria, and probably other varieties and even species of oak. The female insect is furnished with a delicate ovipositor, by means of which she pierces the tender shoots of the tree, and lays her eggs therein. In the centre of the full-grown gall, the larva is hatched and undergoes its transformations, finally (in 5-6 months) becoming a winged insect, and boring for itself a cylindrical exit-hole. The best commercial galls are those which have been gathered while the insect is still in the larval state. Such have a dark olive-green colour, and are comparatively heavy; but after the fly has escaped, they become yellowish-brown in hue, and lighter. Hence they are distinguished in the London market as "blue" or "green," and "white." In Smyrna, they are classified as "white," "green," and "black," the first two sorts generally fetching nearly the same price, while the black obtain considerably more, the approximate quotations being: white and green, per Turkish oke (of 2·83 lb.), 81/2-9 piastres (of 2d.); black, 131/2-14 piastres. The "nuts" come mostly from Melemen, Cassaba, and Magnesia, also from the Syrian coasts, being plentiful on the east of the river Jordan, and are chiefly forwarded to France, England, and Salonica. The triennial yield is said to be invariably the best. They begin to reach Smyrna from the interior towards the end of July. The crop of 1880 was estimated at over 50,000 okes. The province of Aleppo, which used to afford 10,000-12,000 quintals (of 2 cwt.) annually, only exported 3000 in 1871. The galls collected in the Kurdistan mountains are marketed at Diarbekir, and sent thence to Trebizonde for shipment. Bussora, Bagdad, and Bushire also export considerable quantities.
Knoppern, a species of gall formed from the immature acorns of Quercus pedunculata and Q. sessiliflora, are largely used for tanning throughout Austria.
The exports from Aleppo (including yellow berries) in 1880 were:—60 tons, 3600l., to Great Britain; 322 tons, 19,320l., France; 15 tons, 900l., Italy; 44 tons, 2640l., Austria; 55 tons, 3300l., Turkey; 30 tons, 1800l., Egypt; total, 526 tons, 31,560l. In 1878, the figures were 673 tons, 38,400l. Alexandretta exported in 1879 (including yellow berries):—41 tons, 2460l., to England; 299 tons, 17,940l., France; 20 tons, 1200l., Italy; 25 tons, 1500l., Austria; 87 tons, 5220l., Turkey; 6 tons, 360l., Egypt; total 478 tons, 28,680l. The shipments from Trebizonde by steamer in 1880 were (from Turkey):—47 sacks (of 2 cwt.), 188l., to Turkey; 240 sacks, 960l., Great Britain; 264 sacks, 1056l., France; 103 sacks, 412l., Austria and Germany; 26 sacks, 104l., Greece; total, 680 sacks, 2720l.; (from Persia): 25 sacks, 100l., Great Britain; 31 sacks, 124l., France; 30 sacks, 120l., Austria and Germany; total, 86 sacks, 344l. Bushire despatched 5000r. worth to India in 1879. Syra sent 248l. worth to Great Britain in 1879. Venice exported 1745 tons of gall and bark, value 34,906l., in 1879.
The best oak-galls contain 60-70 per cent. of tannic or gallotannic acid, and 3 per cent. of gallic acid. "Rove" is a small crushed gall, containing 24-34 per cent. of gallotannic acid. There are many other varieties of non-commercial oak-gall.
Chinese or Japanese Galls.—These are vesicular protuberances formed on the leaf-stalks and branches of the Rhus semialata [Bucki-amela], a tree of 30-40 ft., common in North India, China, and Japan, ascending the outer Himálaya and the Khasia Hills to 2500-6000 ft., by punctures of the female of Aphis chinensis. The galls are collected when their green colour is changing to yellow, and are then scalded. They are light and hollow, 1-21/2 in. long, and of very varied and irregular form. The Japanese are the smaller and paler, and usually more esteemed. The galls contain about 70 per cent. of tannic or gallotannic acid, and 4 per cent. of another tannin. They are consumed mainly in Germany, for the manufacture of tannic acid.
Hankow exported 30,949 piculs (of 1331/3 lb.) in 1872; and 21,611 piculs, value 136,214 taels (of about 6s.), in 1874. In 1877, the total Chinese export did not exceed 17,515 piculs. Hankow exported 24,7421/2 piculs in 1878, and 28,392 piculs, 59,614l., in 1879; Pakhoi, 62l. worth in 1879; Canton, 31551/3 piculs in 1877, 1939 in 1878, 31631/2 in 1879; Ichang, 1001/2 piculs, 132l., in 1878, 4021/2 piculs, 586l., in 1879; Shanghai, 27,6591/2 piculs in 1879.