barley of the so-called Goldthorpe type (H. zeocriton), used for malting,
has increased. The paleae or outer coverings of the corns of
this variety are somewhat “greasy” in appearance, and do not
adhere so closely to the corn as in the Chevallier. The corns of
Goldthorpe barley possess a small dimple or transverse furrow near
the basal end. Further the basal bristle or rachilla (the prolongation
of the axis or point from which the corn was originally developed)
is invariably covered with long hairs, whilst in the case of Chevallier
it has generally very short hairs. In the variety of Chevallier known
as Archer, however, the rachilla has somewhat long hairs. Further
the corns of Chevallier barley lie nearly vertical, that is almost
parallel to the rachis, whereas in Goldthorpe they are spread out at
a greater angle, hence the name fan or peacock barley given to that
variety commonly known as sprat. It is believed by some brewers
that Goldthorpe barleys never yield malt of so high a quality as
do Chevallier barleys. On the other hand, when well matured,
Goldthorpes work evenly and freely on the malting floors; and from
an agricultural point of view they have the advantage of standing
up better against unfavourable weather conditions on account of
their stouter straws. Numerous fresh varieties of barley are continually
being introduced as a result of artificial cross-fertilization,
but cross-fertilization rarely if ever occurs naturally.
Hungarian two-rowed barleys are excellent as regards quality, and command a high price. The so-called Californian Chevallier and Chilean Chevallier contain a certain admixture of the six-rowed H. vulgare.
Of the imported thin barleys may be mentioned Brewing Californian, Brewing Chilean, Danubian and Smyrna (Yerli), all for the most part six-rowed varieties; also Ouchak, consisting principally of a two-rowed variety. For the manufacture of grain spirit a malt of high diastatic activity is required, and this is largely made from a very thin barley shipped from Odessa.
In the common six-rowed English barley or Scottish bere (H. vulgare), the two lateral rows of spikelets springing from one side of the rachis, either partially or entirely intersect and overlap the alternate lateral spikelets which spring from the opposite side of the rachis. This has given rise to the term “four-rowed barley.” Figs. 1–4 show some typical barleys in the ear.
The production of new varieties by cross-fertilization has of late years attained a degree of almost mathematical precision by the application of the law of inheritance first discovered by Gregor Mendel in 1865, and brought to light in 1901 independently by de Vries, Correns and Tschermak.
Constitution of Barley.—A grain of barley is shuttle-shaped; the end containing the germ which was originally attached to the rachis is known as the proximal end, whilst the opposite end of the corn is called the distal end. A deep furrow runs down the more convex side, which is accordingly denoted the ventral side, the opposite side being distinguished as the dorsal side. Within the ventral furrow at the proximal end is the rachilla already referred to. The skin or husk of a barleycorn consists of two paleae, one adhering to the dorsal side (the palea inferior) and the other to the ventral side (the palea superior); the former overlaps the edges of the latter. The awn or beard is merely an elongation of the palea inferior. If the two paleae are removed from a barleycorn after soaking it in water, it will be seen that there are other skins completely enveloping the embryo and endosperm. These are the true skins, and are known as the pericarp and the testa respectively. It may here be mentioned that A. J. Brown has shown recently that the embryo and endosperm of a barleycorn are enclosed in a semi-permeable membrane, i.e. one which allows the passage of water to the interior of the corn, but not of certain salts and acids. This property appears to be associated with one of the layers of the testa. Next to these skins will be seen the triple layer of thick-walled square-shaped aleurone cells.
The histology of the barleycorn is best studied by the examination of sections under the microscope. The grain consists of two main portions, the embryo or germ, and the endosperm, the storehouse of reserve materials for the growing plant.
The accompanying illustrations show portions of longitudinal sections of a barleycorn magnified to different degrees.
On examining fig. 5, which represents a section of the germ end of a grain of barley cut through the ventral furrow, it will be noticed that the rudimentary leaves, stem and roots are distinguishable. The embryo lies embedded in a mass of cells, the part dividing it from the endosperm being known as the scutellum. Special note should be taken of the elongated cells known as the absorptive epithelial layer, which has certain very important functions to fulfil during the process of germination, notably in feeding the embryo when it begins to develop into a young plant. Next to this, actually between the scutellum and the endosperm, will be seen a layer of empty cells. These at one time in the history and the development of the corn contained starch granules, but this starch was absorbed during its later development by the embryo. It will be observed further that the endosperm is filled with a network of thin-walled cells closely packed with starch granules, and smaller granules of proteïn matter (fig. 6). Nearest the skin will be seen the triple layer of aleurone cells already referred to (fig. 7).
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| Fig. 5.—Median longitudinal section of a barleycorn showing the germ and its appendages. | |
a, Rudimentary leaves or plumules; |
e, Absorptive epithelial layer; |
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| Fig. 6.—Section showing absorptive epithelial layer more highly magnified. | |
d, Walls of starch cells; |
g, Cells filled with starch granules; |
Germination.—The barleycorn in its resting stage is in a state which may be described as one of dormant vitality; it
