_Hordeum perlatum_, _Fructus vel Semen Hordei_; _Pearl Barley_; F.
_Orge mondé ou perlé_; G. _Gerollte Gerste_, _Gerstegraupen_.
=Botanical Origin=—_Hordeum distichum_ L.,—the Common or Long-eared
Barley is probably indigenous to western temperate Asia, but has been
cultivated for ages throughout the northern hemisphere. In Sweden its
cultivation extends as far as 68° 38’ N. lat.; on the Norwegian coast
up to the Altenfjord in 70° N. lat.; even in Lapland, it succeeds as
high as 900 to 1350 feet above the level of the sea. In several of
the southern Swiss Alpine valleys, barley ripens at 5000 feet, and
in the Himalaya at 11,000 feet. In the Equatorial Andes, where it is
extensively grown, it thrives up to at least 11,000 feet above the sea.
No other cereal can be cultivated under so great a variety of climate.
According to Bretschneider,[2699] barley is included among the five
cereals which it is related in Chinese history were sowed by the
Emperor Shen-nung, who reigned about 2700 B.C.; but it is not one of
the five sorts of grain which are used at the ceremony of ploughing and
sowing as now annually performed by the emperors of China.
Theophrastus was acquainted with several sorts of barley (Κριθή), and
among them, with the six-rowed kind or _hexastichon_, which is the
species that is represented on the coins struck at Metapontum[2700] in
Lucania, between the 6th and 2nd centuries B.C.
[2699] _On Chinese Botanical Works_, etc., Foochow, 1870. 7. 8.
[2700] Metapontum lay in the plain between the rivers Bradano and
Basento in the gulf of Taranto.
Strabo and Dioscorides in the 1st century allude to drinks made from
barley, which according to Tacitus were even then familiar to the
German tribes, as they are known to have been still earlier to the
Greeks and Egyptians.
Barley is mentioned in the Bible as a plant of cultivation in Egypt
and Syria, and must have been, among the ancient Hebrews, an important
article of food, judging from the quantity allowed by Solomon to the
servants of Hiram, king of Tyre (B.C. 1015). The tribute of barley paid
to King Jotham by the Ammonites (B.C. 741) is also exactly recorded.
The ancients were frequently in the practice of removing the hard
integuments of barley by roasting it, and using the torrefied grain as
food.
=Manufacture=—For use in medicine and as food for the sick, barley
is not employed in its crude state, but only when deprived more or
less completely of its husk. The process by which this is effected
is carried on in mills constructed for the purpose, and consists
essentially in passing the grain between horizontal millstones, placed
so far apart as to rub off its integuments without crushing it.
Barley partially deprived of its husk is known as _Scotch_, _hulled_
or _Pot Barley_. When by longer and closer grinding the whole of the
integuments have been removed, and the grain has become completely
rounded, it is termed _Pearl Barley_. In the _British Pharmacopœia_ it
is this sort alone which is ordered to be used.
=Description=—Pearl Barley is in subspherical or somewhat ovoid grains
about 2 lines in diameter, of white farinaceous aspect, often partly
yellowish from remains of the adhering husk, which is present on the
surface, as well as in the deep longitudinal furrow with which each
grain is indented. It has the farinaceous taste and odour which are
common to most of the cereal grains.
=Microscopic Structure=—The albumen which constitutes the main portion
of the grain is composed of large thin-walled parenchyme, the cells of
which on transverse section are seen to radiate from the furrow, and
to be lengthened in that direction rather than longitudinally. In the
vicinity of the furrow alone the tissue of the albumen is narrower. Its
predominating large cells show a polygonal or oval outline, whilst the
outer layer is built up of two, three or four rows of thick-walled,
coherent, nearly cubic gluten-cells. This layer, about 70 mkm. thick,
is coated with an extremely thin brown tegument, to which succeeds a
layer about 30 mkm. thick, of densely packed, tabular, greyish or
yellowish cells of very small size; this proper coat of the fruit in
the furrow is of rather spongy appearance.
In some varieties of barley the fruit is constituted of the above
tissues alone and the shell, but in most the paleæ are likewise
present. They consist chiefly of long fibrous, thick-walled cells,
two or four rows deep, constituting a very hard layer. On tranverse
section, this layer forms a coherent envelope about 35 mkm. thick; its
cells when examined in longitudinal section show but a small lumen of
peculiar undulated outline from secondary deposits.
The gluten-cells varying considerably in the different cereal grains,
afford characters enough to distinguish them with certainty. In wheat,
for instance, the gluten-cells are in a single row, in rice they form a
double or single row, but its cells are transversely lengthened.
The inner tissue of the albumen in barley is filled up with large
irregularly lenticular, and with extremely small globular starch
granules, the first being 20 to 35 mkm., the latter 1, 2 to 3 mkm.
in diameter, with no considerable number of intermediate size.
The concentric layers constituting the large granules may be made
conspicuous by moistening with chromic acid.
The layer alluded to as being composed of _gluten-cells_ is loaded
with extremely small granules of albuminous matters (gluten), which
on addition of iodine are coloured intensely yellow. These granules,
which, considering barley as an article of food, are of prominent
value, are not confined to the gluten-cells, but the neighbouring
starch-cells also contain a small amount of them: and in the narrow
zone of denser tissue projecting from the furrow into the albumen,
protein principles are equally deposited, as shown by the yellow
coloration which iodine produces.
The gluten-cells, the _membrane embroynnaire_ of Mège-Mouriès, contain
also, according to the researches on bread[2701] made by this chemist
(1856), _Cerealin_, an albuminous principle soluble in water, which
causes the transformation of starch into dextrin, sugar, and lactic
acid. In the husks (_épiderme_, _épicarpe_ and _endocarpe_) of wheat,
Mège-Mouriès found some volatile oil and a yellow extractive matter,
to which, together with the cerealin, is due the acidity of bread made
with the flour containing the bran.
=Chemical Composition=—Barley has been submitted to careful analyses
by many chemists, more especially by Lermer.[2702] The grains contain
usually 13 to 15 per cent. of water; after drying, they yield to ether
3 per cent. of fat oil, with insignificant proportions of tannic and
bitter principles, residing chiefly in the husks. Lermer further found
in the whole grains, 63 per cent. of starch, 7 of cellulose, 6·6 of
dextrin, 2·5 of nitrogen, a small amount of lactic acid, and 2·4 of ash.
[2701] He actually examined _wheat_, not barley; we assume the chemical
constitution of the two grains to be similar.
[2702] Wittstein, _Vierteljahresschr. für prakt. Pharm._ xii. (1863)
4-23.
The analysis of Poggiale (1856) gave nearly the same composition,
namely, water 15, oil 2·4, starch 60, cellulose 8·8, albuminous
principles 10·7, ash 2·6.
The protein, or albuminous matter consists of different principles,
chiefly insoluble in cold water. The soluble portion is partly
coagulated on boiling, partly retained in solution: 2·5 per cent. of
nitrogen, as above, would answer to about 16 per cent. of albuminous
matters. Their soluble part seems to be deposited in the starch-cells,
next to the gluten-cells, which latter contain the insoluble portion.
The ash, according to Lermer, contains 29 per cent. of silicic acid,
32·6 of phosphoric acid, 22·7 of potash, and only 3·7 of lime. In
the opinion of Salm-Horstmar, fluorine and lithia are indispensable
constituents of barley.
The fixed oil of barley, as proved in 1863 by Hanamann, is a compound
of glycerin with either a mixture of palmitic and lauric acids, or
less probably with a peculiar fatty acid. Beckmann’s _Hordeinic Acid_
obtained in 1855 by distilling barley with sulphuric acid, is probably
lauric acid. Lintner (1868) has shown barley to contain also a little
_Cholesterin_ (p. 420).
Lastly, Kühnemann (1875) extracted from barley a crystallized
dextrogyrate sugar, and (1876) an amorphous lævogyrate mucilaginous
substance _Sinistrin_ (see p. 692); according to that chemist, dextrin
is altogether wanting in barley.
Barley when malted loses 7 per cent.; it then contains 10 to 12 per
cent. of sugar, produced at the expense of the starch; before malting,
no sugar is to be found.
=Uses=—Barley as a medicine is unimportant. A decoction is sometimes
prescribed as a demulcent or as a diluent of active remedies. An
aqueous extract of malt has been employed.