Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/132

112 prized variety known as peaberry is the result of the coalescence of the two seeds within the fruit, thus producing the appearance of a single rounded seed, usually of small size, whence the name. Regarding the famous Mocha or &ldquo;Mokha&rdquo; coffee of Arabia, Mr W. G. Palgrave has the following remarks:—

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The &ldquo;Mocha&rdquo; of the English market is principally the produce of India, but a good deal of American coffee is also passed into consumption under that abused name. The conditions most favourable for coffee planting are found in hilly situations, where the ground is at once friable, well drained, and enriched by the washing down of new soil from above by the frequent rains. The seeds are first sown in a nursery, and the young plants when they are a few inches high are planted out in the permanent plantation at distances from each other of from 6 to 8 feet. The operation of planting is one which requires great care, and much labour must be expended on drainage, weeding, and cleaning the plantation, and in pruning or &ldquo;handling&rdquo; the plants. Chiefly for convenience of securing the crop, the trees are rarely allowed to exceed from 4 to 6 feet in height, and being so pruned down they extend their branches laterally in a vigorous manner. The plants begin bearing in their second year, and by the third year they should yield a fairly remunerative crop. The berries are ready for picking when they have assumed a dark-red colour and the skin shrivels up. Immediately after the berries are gathered they are conveyed to the storehouse, where they undergo the operation of pulping; and on some hill estates in Ceylon, having suitable situation and water supply, the gathered berries are carried by a water run through galvanized pipes to the store. The pulping is performed in an apparatus having two roughened cylinders which move in opposite directions. Between these the berries are carried forward with a flow of water, and the seeds are deprived of their surrounding pulp, being left invested in the skin or parchment. In this condition they are spread out to dry, and as soon as practicable they are freed from the husk or parchment by passing them between heavy wooden rollers and winnowing away the broken husks. The shelled coffee is then sized by passing it down a tube perforated throughout its length with holes of regularly increasing diameter, and the various sizes are next hand-picked to free them from defective or malformed seeds, the coffee is then ready to pack for export. A tree in good bearing will yield from 1 to 2 lb of berries in a year; but its fertility depends largely upon conditions of climate, situation, and soil. Generally trees planted in lofty dry situations and in light soils yield small berries, which give a rich aromatic coffee, while in low, flat, moist climates a more abundant yield of a large-sized berry is obtained. The greater weight of the coarser qualities of coffee more than makes up for the smaller price obtained for them as against the higher cost of the finer growths; and therefore quality is too often sacrificed to quantity. The cultivation of coffee is attended with many risks and much anxiety. In Ceylon, where British capital and enterprise have hitherto found their principal scope, the estates are exposed to the attacks of a most mischievous and destructive rodent, the coffee or Golunda rat. A species of insect called the coffee bug, Lecanium coffeæ, is a still more formidable and alarming pest with which planters have to contend. Of recent years prominent attention has been drawn to two diseased conditions arising in Singalese and Indian plantations by fungus growths. The first, called the coffee-leaf disease, appeared in Ceylon in 1869, and in Mysore a year later. The fungus in this case, Hemileia vastatrix, is endophytous, growing within the substance of the leaf, and while no effective cure has been discovered for it, it is not yet clear that it seriously affects the quality or amount of coffee yielded by the plants. The second, known as the coffee-rot, on the other hand, works great havoc in the Mysore plantations, in which it has been observed, being especially hurtful in wet seasons. This fungus has been examined by Mr M. C. Cooke, who names it Pellicularia kolerota, and describes the affected leaves as being covered with a slimy gelatinous film, under which the leaves become black and quickly drop off, as do also the clusters of coffee berries.

—Microscopic structure of Coffee.

Raw coffee seeds are tough and horny in structure, and are devoid of the peculiar aroma and taste which are so characteristic of the roasted seeds. In minute structure coffee is so distinct from all other vegetable substances that it is readily recognized by means of the microscope, and as roasting does not destroy its distinguishing peculiarities, microscopic examination forms the readiest means of determining the genuineness of any sample. The substance of the seed, according to Dr Hassall, consists &ldquo;of an assemblage of vesicles or cells of an angular form, which adhere so firmly together that they break up into pieces rather than separate into distinct and perfect cells. The cavities of the cells include, in the form of little drops, a considerable quantity of aromatic volatile oil, on the presence of which the fragrance and many of the active principles of the berry depend&rdquo; (see fig. 2). The testa or investing membrane of the seeds has a layer of long cells with a peculiar pitted structure. In chemical composition the seeds are complex, and they contain variable proportions of proximate principles. The following represents the average constitution of raw coffee according to the analysis of M. Payen:—

Cellulose 34 Water ]2 Fat 10 to 13 Glucose, dextrin, and organic acid ... 15 5 Legumin and casein 10 Other nitrogenous substances 3 Caffeine 8 Caffetannate of caffeine and potassium Viscid essential oil (insoluble in water) Aromatic oils (some lighter some heavier than water) Ash .. 3-5 to 5-0 o-ooi 0-002 67 