Starch. In the vegetable kingdom starch is a very widely-diffused body. In almost every growing cell granules of starch may be distinguished by means of the microscope. These granules are of various sizes, and assume a great variety of forms; some are round, others are flat, whilst others are even stellate. These granules are always found mixed with other substances, hut they are easily made distinguishable by the application of a little iodine, which is one of the best tests for starch, and which, coming in contact with it, produces a beautiful blue colour.

Starch 191

Granules of Starch. (A) From wheat and barley; (B) from arrow-root; (C) From Portland sago.

Starch is found in some plants in greater Quantities than in others; it is, however, very generally found in perennial roots and rootstocks, in the stems and in the seed? of plants. It seems stored up in these parts for the future growth of the developing organs of the plant. There are few or no vegetables or parts of plants that are eaten that do not contain starch. We find it in turnips, carrots, potatoes, cabbages, parsnips beans, peas, wheat, barley, oats, and the rest of the Cerealia; in chesnuts, walnuts, hazelnuts, and all other seeds; in the apple, the pear, the plum, the cherry, and all other fruits. In many of these things, however, it is not the distinguishing alimentary ingredient, but it is often separated and used pure as an article of diet. The substances in which it exists in a tolerably pure form, and of which we wish now more particularly to speak, are arrow-root, sago, and tapioca.