Figs. 35 and 36, is unique, being composed of large compound masses of
polyhedral granules from .12 to .02 millimeter in length, the single
granules averaging .02 to .015 millimeter. It does not polarize
actively, as may be seen in the figures, and displays neither rings nor
hilum.
The first sign of maize or corn meal as an adulterant is the thin outer
coat which becomes detached in milling and is not readily crushed. In
yellow corn it has a pinkish color, and simple, longitudinal cells.
Broken rice is sometimes used as a dilutant; it may be recognized by the
brilliant appearance of the hard white particles which may be picked out
of the spice under a hand lens.
The two cereals named (broken rice and maize corn) are the only ones
which are commonly met with that introduce starch.
Wheat bran (Fig. 37) is occasionally added, which can be recognized by
its distinctive structural character and is better understood from an
authentic specimen, which should be soaked in chloral-hydrate.
As modified cereals, we find refuse bread, cracker dust, and stale ship
bread, in which the wheat starch is much changed from its original form
by the heat and moisture, so that at times it might be confused with
leguminous starch, but the softness of the particles and the ease with
which they fall to pieces in water reveal their true name. Oil seed, oil
cake, and husk (Figs. 38, 39, and 40) are very commonly used and are
readily recognized by the peculiar structure of the outer coats of the
seed. The particles, which can be usually found and selected with a
dissecting microscope, should be examined in alcohol or glycerine, or a
mixture of the two, as the outer coats of some seeds, such as mustard,
are swollen by water and become indistinct. Many varieties of the
cruciferous seeds resemble it very much, so that it is difficult to
distinguish them, but it is generally recognized by the outer layer of
hexagonal cells and a middle and inner coating, which consists of
peculiar angular cells, the latter being much larger than the former,
which are the most characteristic feature, and should be compared with
seeds of known origin. After soaking in chloral-hydrate, the remaining
interior layers are, perhaps, more easily made out, in some cases, after
moderate bleaching with nitric acid and chlorate; the interior of this
seed is not blued by iodine.
Peanut, or ground nut cake, is recognized by the characteristic
structure of the red-brownish coat, which surrounds the seed, and
consists of polygonal cells with peculiar saw-toothed thickening of the
walls. The seed itself consists of polygonal cells full of oil and
starch granules, which are globular in form and not easily confused with
pepper starch. The structure of the brown membrane is best made out in
chloral-hydrate, which removes the red color and leaves the fragments of
a bright yellow.
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