. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . Fig. Section of wheat grain (outer coat) X Girdle cells, b. Cerealin cells. the grain—called the skin or testa ; and this is the casewith even the finest ground and purest flours. In wheat the envelope is composed of three- fine• There are probably six in all under very high powers. STARCH GRANULES. 337 membranes. The external and the middle both con-sisting of flattened elongated cells, whose contourspresent a beaded
. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . Fig. Section of wheat grain (outer coat) X Girdle cells, b. Cerealin cells. the grain—called the skin or testa ; and this is the casewith even the finest ground and purest flours. In wheat the envelope is composed of three- fine• There are probably six in all under very high powers. STARCH GRANULES. 337 membranes. The external and the middle both con-sisting of flattened elongated cells, whose contourspresent a beaded appearance, and which are more orless dove-tailed into each other. The long axis of the cells in the middle coat aredisposed at right angles to those in the external—whichare arranged with their long axis corresponding withthat of the grain. The external coat is made up of two or three layersof cells, the middle of only one—and the cells of thelatter are smaller and more uniform in size. Unicel-lular cells ( hairs ^ with pointed apices, come off in. Fig. 75.—Wheat. Tissue from the testa ot the grain, showingthe appearance of the cells forming its outer and inner membranes.(X 100) tufts from the external coat at one extremity of thegrain; these hairs are simply prolongations of thecells. The internal coat is made up of irregularly roundedopaque-looking cells, which frequently contain one ormore oil globules. The starch granules, comprisingalmost the whole of the interior of the grain, are in-cluded within a thick-walled cellular network. In barley the envelopes are similar to those in wheat,except in the following respects :—The cells forming theexternal coat are smaller and more uniform in size 33^ LABORATORY WORK. than in wheat, and their outUne is serrated instead ofbeaded ; they carry, moreover, short thick hairs. Thecells of the middle coat are more elongated, and notbeaded—or very imperfectly so. Those of the innercoat are somewhat smaller.
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