HOP (German, Hop fen; French, honblon), Humulus Lupulus, L., the sole representative of its genus, an herbaceous twining plant, belonging to the natural order Can-nabinaceee, which is by some botanists included in the larger group called Urticaccce by Endlicher. It is of com-mon occurrence in hedges and thickets in the southern counties of England, but is believed not to be native in Scotland. On the Continent it is distributed from Greece to Scandinavia, and extends through the Caucasus and Central Asia to the Altai Mountains. It is common, but doubtfully indigenous, in the northern and western States of North America, and has been introduced into Brazil, Australia, and the Himalayas.
It is a dioecious perennial plant, producing annually several long twining roughish striated stems, which twist from left to right, are often 15 to 20 feet long, and climb freely over hedges and bushes. The leaves are stalked, opposite, 3-5 lobed, and coarsely serrate, and bear a general resemblance to those of the vine, but are, as well as the whole plant, rough to the touch; the upper leaves are sometimes scarcely divided, or quite entire. The stipules are interpetiolar, each consisting of two lateral ones united, or rarely with the tips free. The male inflorescence (fig. 1, A) forms a panicle; the flowers consist of a small greenish five parted perianth (a) enclosing five stamens, whose anthers (6) open by terminal slits. The female inflorescence (fig. 1, B) is less conspicuous in the young state. The catkin or strobile consists of a number of small acute bracts, with two sessile ovaries at their base, each subtended by a rounded bractlet (c). Both the bracts and bractlets enlarge greatly during the development of the ovary, and form, when fully grown, the membranous scales of the strobile (fig. 2, a). The bracts can then only be distinguished from the bract-lets by being rather more acute and more strongly veined. The perianth (fig. 1, d) is short, cup-shaped, undivided, and closely applied to the ovary,' which it ultimately encloses. In the young strobile the two purple hairy styles (e) of estch ovary project beyond the bracts. The ovary contains a single exalbuminous seed, containing a spirally-coiled embryo (fig. 2, b).
The ovary and the base of the bracts are covered with a -yellowish powder, consisting of minute sessile grains (see vol. iv. p. 91, fig. 48) called lupulin or lupulinic glands (see vol. i. p. 381). These glands (fig. 2, c) are stated by Stoddart to be from to inch in diameter, like flat-tened subovate little saucers in shape, and attached to a short pedicel; by the expansion of the central portion during growth their apex ultimately becomes convex instead of concave. The upper or hemispherical portion consists of a delicate continuous membrane, and the lower part of tabular polyhedric cells. The stalk is not perceptible in the gland as found in commerce. When fresh the gland is seen to be filled with a yellowish or dark brown liquid; this on drying contracts in bulk and forms a central mass. The contents of these glands, according to Lermer, are chiefly wax (myricylic palmitate) and resins, one of which is crystalline and unites with bases; with these the bitter acid of hops is present in small proportion. It is to these lupulinic glands that the medicinal properties of the hop are chiefly due. By careful sifting, about 1 oz. may be ob-tained from 1 ffi> of hops, but the East Kent variety is said to yield more than the Sussex hops.
In hop gardens a few male plants, usually three or four to an acre, are sometimes planted, that number being deemed sufficient to fertilize the female flowers. It is stated, however, that the female plant produces sufficient male flowers for self-fertilization (Royle). The blossoms are produced in August, and the strobiles are fit for gathering from the beginning of September to the middle of October, accord-ing to the weather.
The cultivation of hops for use in the manufacture of beer dates from an early period. In the 8th and 9 th cen-turies hop gardens, called "humularia" or "humuleta," existed in France and Germany. In the herbarium of Apuleius (1050 A.D.), the hop (" hymele") is said to have been put in the usual drinks of England on account of its good qualities. Until the 16th century, however, hops appear to have been grown in a very fitful manner, and to a limited extent, generally only for private consumption; but after the commencement of the 17th century the culti-vation increased rapidly. At the present time England produces a larger quantity than any other country in Europe. Formerly several plants were used as well as hops to season ale, hence the name " alehoof " for Nepeta Glechoma, and " alecost" for Balsamita vulgaris. The sweet gale, Myrica Gale, and the sage, Salvia officinalis, were also similarly employed. Various hop substitutes, in the form of powder, have been offered in commerce of late years, most of which appear to have quassia as a chief ingredient.
The young tender tops of the hop are in Belgium cut off in spring and eaten like asparagus, and are forced from December to February. They are not only considered a delicacy, but valuable as a diet for anaemic, scrofulous, and rachitic persons.
Hops are extensively cultivated in parts of New England, New York, and Michigan, and most of the hops consumed in the United States are supplied by those districts. Al-though the hop was introduced into America nearly 250 yeara ago, and its cultivation encouraged by legislative enactments in 1657, it is only about seventy-five years since its culture was commenced on an extensive scale ; but from that time the progress has been rapid, and hops have been grown in nearly every State in the Union. The amount produced in the United States was estimated in 1840 at 6196 bales, in 1850 at 17,485, in 1860 at 54,960, and in 1870 at 127,283. As in England, the hop is subject to disease and blight, and in consequence the crop is variable ; thus, in 1869, 69,463 bales were exported from New York and none imported, and in 1873 only 315 bales were exported and 20,885 imported. The English cluster and grape hops seem to be most generally cultivated in New York and Wisconsin. Hops are also grown largely in Bel-gium, Prussia, France, Wiirtemberg, and central Germany. In 1879 only 7153 cwts. of hops were exported from England chiefly to Australia and other British possessions, while 262,765 cwts. were imported, of which 108,306-cwts, were derived from the United States, 63,485 cwts. from Belgium, 50,567 from Germany, 26,796 from Holland, and smaller quantities from France and British. North America. The first packages of hops collected in England often fetch an extravagant price, and are some-times disposed of with remarkable celerity. The first pocket of hops gathered in 1879 is said to' have been picked, dried, sent to London, sold by auction, subjected to hydraulic pressure, packed and banded with iron, covered with three coats of paint, and despatched to an Indian mail steamerall within twenty-four hours. The better qualities are usually packed in fine and the inferior in coarse sacking. In Germany two varieties of the hop are distinguished, the August and the autumn hop, the former being preferred.
The stem of the hop abounds in fibre similar to that of hemp and flax, and has been used in Sweden in the production of a strong durable white cloth. Hitherto it has been usual to steep the stem in water during the whole winter in order to separate the fibre easily. A much quicker process has, however, been patented, by which the-fibre can be speedily extracted. This process consists in boiling the stems first for three quarters of an hour in' alkaline lye, and then, after rinsing in water, for the same time in acetic acid ; the fibre is thus obtained in a state fit for bleaching. The leaves, stem, and root possess also an astringent property, and their use for tanning purposes; was hence at one time patented in England. The leaves have also been recommended as fodder in the fresh state, mixed with other materials, and are said to increase the-quantity and improve the quality of milk yielded by cows.. The stems or " bine " are usually burned in the hop garden.. The spent hops from breweries form excellent manure o for light soils, and together with the leaves should be re-turned to the hop-gardens, the materials absorbed from: the ground by the hop plant being thus in Some measure restored to it.
By distillation with water, hops yield 0-9 per cent, of a; volatile oil, of a greenish colour if from fresh, but reddish-brown if from old hops. Exposed to the air it resinifies. This oil, according to Personne, contains valerol, C6H10O,. which soon passes into valerianic acid, 0T to 0-17 of this acid having been found by Mehu in the lupulinic glands.. The unpleasant odour of old hops is due to this change,-which may be prevented or retarded by exposure to the action of sulphurous acid gas. For medicinal use fresh -hops which have neither undergone this change nor been treated with sulphurous acid should be used. For brewing; purposes, according to Liebig, the use of sulphured hops is not objectionable. The bitter acid principle, C32HB0O7, to which hops probably owe their tonic properties, although noticed by Payen, was first obtained in the pure state by Lermer in 1863. It crystallizes in large rhombic prisms, and is soluble in ether. It has been variously called lupulin, lupuliue, lupulite, and humulin. Griessmayer (1874) has shown that hops contain also in small proportion a liquid volatile alkaloid, not yet analysed, which has the odour ol-eoma ; to this alkaloid its narcotic property is perhaps due. The same chemist found trimethylamiue in hops. Etti' (1876-78) has found in the scales of the hop strobiles an astringent principle, humulotannic acid, C60H48O2R, which is incapable of precipitating gelatin, but which, when boiled-in alcohol or water or heated to 130° G, changes to a red substance, phlobaphen, C5()H46 0 25, whose solution in alcohol possesses that property. Etti likewise obtained a crys-talline white and an amorphous brown resin, also malate, citrate,nitrate, phosphate, and sulphate of potassium, and pectic acid.
The use of hops in medicine dates from a very early period. Coles, in his History of Plants (1657), says"They are good to cleanse the kidneys of gravel and provoke urine; they likewise open obstructions of the liver and spleen, and cleanse the blood and loosen the belly; and as they cleanse the blood, so consequently they help to cure _ eruptions of the skin." Brooke's Dispensatory (1753)reeom-mencls them also as an alterative, and as a remedy for hypo-chondriasis. Hops are, however, but little used in medicine at the present day, although official in the British and United States Pharmacopoeias. According to Bartholow hops in-crease the action of the heart, excite the cutaneous circula-tion, and cause diaphoresis. A slight cerebral excitement is first produced, soon followed by a disposition to sleep. Hops also possess someanaphrodisiac properties. The preparations used are the tincture, infusion, and extract, the oleoresin, and the lupulinic glands. The drug is generally employed either as a stomachic in dyspepsia, or to allay nervous irritability or cerebral excitement in delirium tremens, where the use of opium is inadmissible. A combination of the tinctures of lupulin and capsicum is said to be one of the best substitutes for alcoholic stimulants when their habitual use is to be discontinued. A pillow stuffed with hops forms a well-known domestic remedy for sleeplessness, and a bag of hops dipped in hot water is often used as an ex-ternal application to relieve pain or inflammation, especially of the abdominal organs.
See Fliickiger and Hanbury, PharmacograpMa, 2d ed., p. 551 ; Bentley and Trimen, Med, Plants, No. 230 ; Griessmayer, Ainer. Journ. Pharm., Aug. 1876, p. 360; Etti, in Dingler's Polyt. Journ. cexxvii. p. 491 ; ecxxviii. pp. 354, 357 ; Bartholow, Mat. Med., p. 362; Watson, Rural Encyclopaedia, ii. pp. 686-699; Darwin, Climbing Plants, p. 2 ; Scot, Perfite Platforme of a Hopipe Garden, 1576 ; Freake, Humalus Lupulus in Gout, 1806 ; La Belgique Horticole,
1851, t. i. 311 ; Perin, Culture du Soublon, Strasburg, 1874 ; and for details as to the cultivation and varieties and the picking and preparation of hops, and their employment in the making of beer, see AGRICULTURE, vol. i. p. 381, and BREWING, vol. iv. pp. 272-273. (B. M. H.)
Issletb (Archiv der Pharmacie, May 1880) has further elucidated the chemical relationship of the constituents of the resin, essential oil,. and hitter principle.