“That close resemblance,” replied his uncle, “is explained by the fact that potato starch and laundry starch are at bottom the same thing. Both substances are chemically known as fecula; but laundry starch is made from cereals, particularly wheat, while fecula, properly speaking, comes either from potatoes or from various grains and roots. “Like the starch of the potato, laundry starch is in the form of superposed leaflets, but its grains are much smaller: ten thousand would hardly be enough to make a pellet the size of a pin’s head. And there are some still smaller. It would take sixty-four thousand grains of Indian corn starch to make a pin’s head or, to be more exact, to fill the inside of a cube measuring one millimeter on a side; and in the case of the beet it would take ten millions. You see that in spite of their excessive smallness, a smallness that makes them invisible to the naked eye, the starch grains of the potato are giants in comparison. “It is chiefly by the varying size of their microscopic grains that the starches of different kinds are distinguished from one another. In substance and structure they are all alike. Placed in warm water, their grains swell, burst, expand their leaflets, and the starch, from whatever source, is changed into a glutinous jelly. “Starch is the food supply of plant-life. Wherever we find buds that are intended to develop by themselves, wherever we find germs, there also we shall find a supply of starch serving as a sort of food reserve. Hence this peculiar provision is met with in tubers, bulbs, bulblets, seeds, and fleshy roots. Now when these buds and germs develop, the starch becomes, in the process of vegetation, a kind of sugar which, being soluble in water, can be sent to all parts of the young plant and serve it for food.