. The cereals in America. Grain. 36 THE CEREALS IN AMERICA unripe grain within two layers of cells, the inner and outer integuments of the ovulary. In the mature grain the inner integument may have been absorbed, leaving only the outer, known as the testa. The testa is in turn enclosed by the peri- carp, corresponding to the pod in the pea. The pericarp is composed of three rows of cells and con- stitutes a rather larger portion of the grain than do the testa and nucellus together. These envelopes are sometimes spoken of. Cross section of grain of wheat on the left. (From micro- photograph by
. The cereals in America. Grain. 36 THE CEREALS IN AMERICA unripe grain within two layers of cells, the inner and outer integuments of the ovulary. In the mature grain the inner integument may have been absorbed, leaving only the outer, known as the testa. The testa is in turn enclosed by the peri- carp, corresponding to the pod in the pea. The pericarp is composed of three rows of cells and con- stitutes a rather larger portion of the grain than do the testa and nucellus together. These envelopes are sometimes spoken of. Cross section of grain of wheat on the left. (From micro- photograph by Tolman.) Transverse section, on the right, of an unripe grain enlarged about 100 times from drawing by Bessey. I , ovary wall or pericarp ; 2, outer integument ; 3, inner integument; 4, remains of nucellus ; 5, aleurone cells ; 6, starch cells. collectively as the bran. Bessey ^ and Snyder' portions of the wheat grain as follows : Embryo . . . ' . Aleurone layer ..... Endosperm ...... Seed covering or bran .... give different Per cent 6- 7 3- 4 82-86 5 Girard gives the per cent of embryo in four varieties of wheat as , , and respectively.^ Since the mill products of wheat average considerably less than nine per cent crude fiber, and since seventy per cent of a wheat grain is converted into flour, it follows that the seed coats of the wheat grain must either be considerably less than 1 Neb. Bui. 32, p. III. 2 Harry Snyder: The Chemistry of Plant and Animal Life, p. 278. 3 Compt. Rend. Acad. Sci., Paris, 124 (1897), p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hunt, Thomas Forsyth, 1862-1927. New York, O. Judd company;
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