Starch, it would seem from this, is the prime food element of the human family, the chief factor in the upbuilding of a race, because a fundamental aliment of our bodies.
If the starch factories do not make, in the true sense, the product of their mills, it may be to the point to consider how this all-important substance comes into existence. The organic chemist tells us that starch is a ternary compound, and this agrees closely with the definition laid down by the dictionaries, only they add that it is odorless, tasteless, and insoluble in water. It is one of the proximate principles of plants, and is stored in the form of granules wonderfully variable in size and shape, but each kind having a type that is adhered to with much regularity. For example, the ordinary potato (Solanum tuberosum L.) produces a starch granule that is characterized by a form resembling the shell of the oyster. [Fig. 1] is from a camera drawing of a cell from the center of a potato, with portions of adjoining cells, all of which were packed full of starch, a few grains only being represented.
Starch is acted upon differently by reagents, one of the leading tests for it being a solution of iodine. A drop of a very weak solution will determine the presence of starch in a cuff or shirt front by leaving a blue spot or streak where the iodine has been applied. By means of this reagent the student of plant tissues is readily able to locate starch when present in any slice of tissue he may have made. He would, for example, find much more starch in the tuber of the potato than in any other portion of the plant, and there the grains will be found many times larger than in the stem or the cells of the green leaves. Of the relation of the starch in the leaves to that in the underground stem something may be said later in this paper.
In the corn plant the starch is stored chiefly in the grain, and not in the subterranean portions, as in the potato. The granules of the corn starch are much smaller than those of the potato, as indicated by [Fig. 2], which is from a camera drawing of a cell from a grain of corn and made to the same scale as [Fig. 1]. The granules are oval and not much marked with striæ or lines, but chemically the substance is the same in both cases.
Another leading starch is that of wheat, the form of the grains of which is shown in [Fig. 3]. While somewhat larger than the corn-starch granules, they are not otherwise widely different.
Fig. 3.—Starch Granules of Wheat.
Fig. 4.—Starch Granules of Rice.
One could scarcely overlook the starch produced by the rice plant, for it feeds more people than the potato, corn, or wheat. The relative size and form of the rice-starch granules are shown in [Fig. 4]. It is seen that the grains are not large, and with a strong tendency to break up into small angular pieces.