32 AMERICAN WHEAT AND CORN. 



Under these outer coverings are three membranes, known as the testa 

 or episperm, the legmen, and the embryous envelope. The testa is a 

 compact affair, and carries the coloring matter of the bran. The 

 teginen is an extremely thin membrane not easily seen except where 

 it becomes thick and just under the testa in the heart of the crease. It 

 is not of importance from a milling point of view. The testa and teg- 

 men form about 2 per cent, of the grain. 



The embryous membrane is a continuation of the embryo around the 

 endosperm or floury portion of the grain. It is composed of cells which 

 are often erroneously termed gluten cells, but the true gluten cells are 

 scattered through the endosperm. The cells of the embryous mem- 

 brane contain little or no gluten, and as they are a continuation of the 

 embryo it must be nearly as undesirable to allow them in the finished 

 flour as the germ itself. 



The endosperm is by far the largest portion of the grain, and it is 

 that which is the object of all milling processes to separate from the 

 rest of the wheat and grind to flour. 



It consists of large cells containing the granules of starch and the 

 gluten. At the exterior, nearer the embryous membrane, it is much 

 harder than in the center and contains much more gluten. In all 

 methods of gradual reduction, therefore, the center is of course reduced 

 first, and, being very starchy, is only fit for a low-grade flour, while the 

 richest part of the endosperm, being harder and closely attached to the 

 tough bran coats, is to a certain extent lost, or so contaminated with 

 small pieces of the bran as to injure the color of the flour, furnishing 

 what is known as bakers' grades. 



By the old-fashioned low-milling process, or grinding between stones 

 placed very close together and bolting, it was impossible to obtain a 

 flour entirely free from contamination. The advance to high milling 

 with stones far apart, allowing the middlings which were produced to 

 be purified before grinding to flour, was a step which made it possible 

 to make from winter wheat an excellent and pure flour. When, how- 

 ever, spring wheat, with its hard and brittle outer coats, became im- 

 portant commercially, it was necessary to resort to the roller methods 

 of milling, which, in conjunction with peculiar purifying machinery, 

 would furnish a flour free from all undesirable impurities. 



This process is so complete that an examination and chemical analysis 

 of the products are of great interest, as showing how the different con- 

 stituents of the grain are divided. It is unnecessary, however, to de- 

 scribe the process itself, long accounts of which can be found in the 

 millers' journals of the day and in the Census of 1880, Vol. Ill, Statistics 

 of Agriculture. It is sufficient merely to know the names of the prod- 

 ucts and the portion of the grain from which they come. 



The first series, consisting of seventy-two specimens, is from the mill 

 of 0. A. Pillsbury & Co., Minneapolis, Minn., known as the Pillsbury 



