LABORATORY STUDIES FOR BREWING STUDENTS. SECTION I BARLEY AND MALTING. PART I. A STUDY OF THE BARLEY CORN. Examine a Grain of ordinary English Chevalier Barley. Note that the grain is spindle-shaped or fusiform, and is about one-third of an inch in length. On closer inspection it will be observed that one end of the grain, which is somewhat sharper than the other, shows signs of having been fractured. This is the end which was originally attached to the ear of barley previous to threshing, and is consequently the lower end of the grain. Observe that a deep, narrow furrow runs down the more convex side of the grain. This furrow is termed the ventral furrow, and the side of the grain on which it is situated is termed the ventral side. して The other side-which is flatter than the ventral side is termed the dorsal side. Examine the ventral furrow towards the lower end of the grain, and notice that within it there lies a thin bristle. Remove the bristle with the point of a dissecting needle, and examine it under the microscope with a low-power (1 inch) lens. It will be found that it is covered with fine lateral hairs. When removing the bristle, usually termed the basal bristle, from the ventral furrow, notice that it is attached to the base of the grain close to the point where the grain was originally connected with the ear. The basal bristle, or rachilla, is merely the prolongation of the axis or point from which the corn was originally developed. It has no physiological importance, but its appearance is sometimes useful in assisting to discriminate between different kinds of barley. Examine a Grain of Barley when softened by soaking in Cold Water for about forty-eight hours. -Observe that it is covered by a thick skin. A careful examination will show that this skin is not continuous round the grain, but consists of two separate portions, one closely adhering to the dorsal and the other to the ventral side of the corn, and that the skin on the dorsal side overlaps the edges of the skin covering the ventral side. With care the two skins may be removed entire, and it will then be noticed how much their general structure resembles that of a grass leaf-the dorsal skin especially showing conspicuous longitudinal veins, or vascular bundles, similar to those in a grass leaf. Compare the Barley under Examination with an Ear of Unthreshed Barley.-It will be noticed that the furrowed or ventral side of a grain of barley is the side which is turned inward towards the stem, or rachis. It will also be noticed that the awn, or beard, of unthreshed barley is merely a prolongation of the skin which covers the dorsal side of the barley corn, and that it is broken off during the threshing process. Compare an Ear of Ripe Barley with a Spike of Barley when in Flower.-A general similarity between the two is apparent. The flowers are arranged alternately on the stem or rachis, and the outer covering of the flower with its long awn at once suggests that this covering is the same as the thick skin of the barley corn. Detach a Flower from the Spike.-Notice that the outer covering of the flower is composed of the same two leaf-like structures which were found enclosing the barley corn. The one which partially wraps round the other and is terminated by the awn, is called the palea inferior, and the other the palea superior. Open the Flower and Remove the Palea Inferior. The organs of the flower will then be observed lying within the fold of the palea superior. These consist of: (a) An ovary. (The female organ.) (b) Three pollen-bearing anthers, each supported on a hair-like filament. (The male organs.) (c) Two minute transparent leaflets called lodicules which are situated at the base of the ovary and embrace it. (The lodicules are sometimes regarded as abortive petals of the flower.) FIG. 3. Ovary of Barley FIG. 1.-Barley Flower Remove the Ovary with a Dissecting Needle and Examine it under a low Microscopic Power. It is roughly heart-shaped and is surmounted by two hairy stigmata adapted for the purpose of retaining pollen grains. On the inner side of the ovary (the side nearest to the rachis), a furrow will be seen which is retained during development into a barley corn and thus represents the ventral furrow. |