Morphology of the barley grain with reference to its enzym-secreting areas . fthe pericarp are sometimes foundscattering fragments of the inner epidermis of the ovary, their cellsalso elongated lengthwise with the grain. The testa is the remnant of the inner of the two integuments thaionce existed inside the ovary wall, the outer one having cells of the testa are crushed almost to the point of disappearance,being represented in the ripened grain by a mere line. In intimate con-tact with the testa and much better preserved is the investing mem-brane of thenucellus. It consists o
Morphology of the barley grain with reference to its enzym-secreting areas . fthe pericarp are sometimes foundscattering fragments of the inner epidermis of the ovary, their cellsalso elongated lengthwise with the grain. The testa is the remnant of the inner of the two integuments thaionce existed inside the ovary wall, the outer one having cells of the testa are crushed almost to the point of disappearance,being represented in the ripened grain by a mere line. In intimate con-tact with the testa and much better preserved is the investing mem-brane of thenucellus. It consists of moderately thickened cells flattenedby pressure. On the inside of this are occasional patches of pa ri l v reab-sorbed cell walls, remnants of the nucellar tissue. According to Brown,1the investing membrane of the nucellus probably forms the semiperme-able membrane, though the inner integument may also be concerned. ! Brown, A. J. On the existence of a semipermeable membrane inclosing the seeds of some of the Gram-inese. Annals of Botany, v. 21, no. 81, p. 79-87, . Fig. l. A grain of 2-rowed barley: A, Dorsal view;B, ventral view. 4 BULLETIN 183, U. S. DEPARTMENT OF AGRICULTURE. THE SEED PROPER. The external layer of the seed proper is the aleurone layer. Itassumes a greater importance in barlej^ than in other grains. Itnormally consists of a stratum of two or three rows of cubical cellsgorged with protein contents. Their appearance shows them to becells of unusual vigor and vitality. The greater part of the spacewithin the aleurone layer is occupied b}r the starch endosperm. Thisis. as in all grasses, a typical storage tissue. Its cells are thin walled and packed with starch granules. Thenuclei are feeble and distorted by the pres-sure of the accumulated starch. At theproximal end of the starch endosperm andpartly embedded in its tissue lies the embryo,the morphology of which is observed withease but interpreted with difficulty. Fromits nature, it must contain all the
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