Though the two mericarps are closely united, they adhere only by the thin pericarp, enclosing when ripe a lenticular cavity. On each side of this cavity, the skin of the fruit separates from that of the seed, displaying the two brown vittæ of each mericarp. In transverse section, the albumen appears crescent-shaped, the concave side being towards the cavity. The carpophore stands in the middle of the latter as a column, connected with the pericarp only at top and bottom.
Corianders are smooth and rather hard, in colour buff or light brown. They have a very mild aromatic taste, and, when crushed, a peculiar fragrant smell. When unripe, their odour, like that of the fresh plant, is offensive. The nature of the chemical change that occasions this alteration in odour has not been made out.
The Indian corianders shipped from Bombay are of large size and of elongated form.
Microscopic Structure—The structural peculiarities of coriander fruit chiefly refer to the pericarp. Its middle layer is made up of thick walled ligneous prosenchyme, traversed by a few fibro-vascular bundles which in the zigzag ridges vary exceedingly in position.
Chemical Composition—The essential oil of coriander has a composition indicated by the formula C₁₀H₁₈O, and is therefore isomeric with borneol. If the elements of water are abstracted by phosphoric anhydride, it is converted, according to Kawalier (1852), into an oil of offensive odour, C₁₀H₁₆.
The fruits yield of volatile oil from 0·7 to 1·1 per cent.; as the vittæ are well protected by the woody pericarp, corianders should be bruised before being submitted to distillation. Trommsdorff (1835) found the fruits to afford 13 per cent. of fixed oil.
The fresh herb distilled in July when the fruits were far from ripe, yielded to one of us (F.) from 0·57 to 1·1 per mille of an essential oil possessing in a high degree the disagreeable odour already alluded to. This oil was found to deviate the ray of polarized light 1·1° to the right when examined in a column 50 mm. long. The oil distilled by us from ripe commercial fruit deviated 5·1° to the right.
Production and Commerce—Coriander is cultivated in various parts of Continental Europe, and, as already stated, to a small extent in England. It is also produced in Northern Africa and in India. In 1872-73, the export of coriander from the province of Sind[1255] was 948cwt.; from Bombay[1256] in the same year 619 cwt. From Calcutta[1257] there were shipped in 1870-71, 16,347 cwt.
Uses—Coriander fruits are reputed stimulant and carminative, yet are but little employed in medicine. They are however used in veterinary practice, and by the distillers of gin, also in some countries in cookery.