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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,

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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

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collectively as the bran. Bessey1 and Snyder give different portions of the wheat grain as follows:

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Girard gives the per cent of embryo in four varieties of wheat as 1.50, 1.41, 1.35 and 1.16 respectively.3

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. Bul. 32, p. III.

Harry Snyder: The Chemistry of Plant and Animal Life, p. 278. 3 Compt. Rend. Acad. Sci., Paris, 124 (1897), p. 878.

five per cent or the seed coats must be largely composed of something else than crude fiber.

65. Physical Properties.-Richardson found as the result of 377 determinations that there were about 12,000 grains in a pound of wheat: in some samples there were less than 8,000, while in others 24,000 grains to the pound. Obviously, so far as individual grains are concerned, one bushel of seed in the one case would be equivalent to three bushels in the other. Pammel and Stewart report variations in the specific gravity of American grown varieties from 1.146 to 1.518.

Generally the

The hardness of the grain varies greatly. harder grains contain the higher per cent of total nitrogen and of gluten. The relation between hardness and specific gravity has not as yet been clearly demonstrated, although Lyon has shown that high specific gravity is associated with low nitrogen content.1

Kornicke and Werner state that the specific gravities of the various chemical constituents of the wheat grain are as follows: Starch, 1.53; sugar, 1.60; cellulose, 1.53; fats, 0.91-0.96; gluten. 1.30; ash, 2.50; water, 1.00; air, .001293.

The standard (and generally legal) weight per bushel (2150.42 cu. in.) of wheat is sixty pounds. The weight of a measured bushel not infrequently varies from fifty-five to sixty-five pounds per bushel, and greater extremes have been noted.

The color of the grain varies from a very light yellow through varying grades of amber to dark red. Hardness of grain and high nitrogen content are usually associated with the deeper red color.

The grain may vary in length, in transverse or cross section outline, or in depth of crease or furrow. All of these characters may be used in describing varieties of wheat. (201)

1 A Method for Improving the Quality of Wheat for Breadmaking. Thesis for degree Ph.D., Cornell, 1904.

* Handbuch des Getreidebaues Bd. 2s. 120. Berlin. 1884.

66. Composition.

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The following table gives the minimum

maximum and average analyses of 310 American grown samples of grain and seven samples of wheat straw:1

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67. Water. The analyses show that wheat contains ten to eleven per cent of water. This represents the moisture in the samples as analyzed, often after they have stood in the dry room of the laboratories. What percentage of water wheat contains as it goes on the market cannot be stated, but it has been shown to vary largely from day to day with varying conditions of the atmosphere. In California, where the atmosphere inland is very dry at harvest, this subject is a matter of considerable commercial importance. It is claimed that the moisture that this California wheat will absorb during a voyage from San Francisco to Liverpool will sometimes increase its weight enough to pay the entire cost of freight. Wheat bought inland and kept in warehouses all the season would increase in a similar manner upon exposure.

Experiments by Hilgard and O'Neil, of the University of California, indicated that wheat of the inland of California might increase twenty-five per cent in weight by the absorption of water when transported to a temperate climate, while a gain of five to fifteen per cent mignt be looked for with absolute certainty. A difference of nine per cent was observed in twenty-four hours. Brewer found a difference of from five to 1 U. S. Dept. of Agr., Office of Exp. Stations E. S. B. II.

eight per cent of water in wheat in a room in which the moist air of New Haven circulated in September and in February when the room was heated by a furnace. Richardson found that two days were sufficient to equalize the moisture in samples of flour which originally varied from less than eight to over thirteen per cent. Afterward the water in the samples fluctuated with the humidity of the air.

68. Ash.-Lawes and Gilbert give the average composition of the ash of the grain and straw of wheat on an unmanured plat during twenty years as follows:1

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Fifty per cent more phosphoric acid than potash is laid up in the grain, while in the straw five times as much potash as phosphoric acid is accumulated. A relatively large amount of magnesia is stored in the grain, while relatively more lime is to be found in the straw. More than two-thirds of the ash of straw is silica. Formerly it was held that the silica helped to stiffen the straw. This view is no longer held, since the accumulation of silica is greater in the upper portion of the stem.

It has been shown that the ash constituents of normally ripened seeds of wheat are remarkably uniform, but vary some 1 Jour. Am. Chem. S. Vol. XLV (1888), p. 100.

what with the season, as does the nitrogen, on account of irregularities in the ripening of the seed, and only slightly on account of different modes of manuring except in cases of abnormal soil exhaustion. From three plats manured as indicated in the table below, Lawes and Gilbert found the average annual yield of total mineral constituents during sixteen years to be as follows: 1

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119.2

142.2

With ammonium salts alone 23.0

Where ammonium salts alone were used the grain showed exhaustion both of potash and phosphoric acid-especially the latter, while in the straw there was a marked deficiency of the former.

69. Protein.-In 310 analyses of American grown wheats compiled to September 1st, 1890, the protein (N x 6.25) varied from 8.1 to 17.2 per cent, with an average of 11.9 per cent in samples containing an average of 10.5 per cent water, or in other words, the protein was 13.3 per cent of the dry matter of the grain. Koenig reports the range in protein of the wheat grain from various parts of the world to be from five to twentyfour per cent, but that seventy-five per cent of all analyses fall within eight to fourteen per cent."

The nitrogenous compounds of wheat consist principally, if not wholly, of proteids, of which five have been recognized and studied by Osborne and Voorhees as follows: (1) a globulin, 0.6-0.7 per cent of the grain; (2) an albumin, 0.3-0.4 per cent; (3) a proteose, 0.2-0.4; (4) gliadin, 4.25 per cent; and (5) glutenin, 4-4.5 per cent. (71, 72)

1 Jour. Am. Chem. Soc. Vol. XLV (1888), p. 20.

U. S. Dept. of Agr., Div. of Chem. Bul. 4, p. 69.

8 The Proteids of the Wheat Kernel. By Thomas B. Osborne and Clark C Voorhees, Am. Chem. Jour. XV (1893), pp. 392-471.

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