=Glycogen=, or "animal starch," is one of the most widely distributed reserve foods of the animal body; in fact, it is the only known form of carbohydrate-reserve in animal tissues. But it is present only rarely in plants. It occurs in certain fungi, particularly in yeasts. In the animal body, glycogen is found in all growing cells; also in the muscles and blood; but most largely in the liver, where it is stored in large quantities. The glycogen found in yeasts is identical with that found in animal tissues. The quantity of glycogen in a yeast cell increases rapidly as the yeast grows during the fermentation process. Glycogen is a white, amorphous compound, readily soluble in hot water, forming an opalescent solution similar in appearance to the solutions of soluble starch. It is strongly dextrorotatory (specific rotatory power +190°), is colored brown by iodine, and is hydrolyzed to dextrin and maltose, and finally to glucose. =Lichenin=, =para dextran=, and =para isodextran= are dextrosans which have been isolated from various lower plants. They all yield glucose when completely hydrolyzed. They resemble starch in chemical properties, but differ from it in physical form, etc. (B) LEVULOSANS =Inulin= replaces starch as the reserve food carbohydrate in a considerable number of natural orders of plants, particularly in the Compositae. It is the carbohydrate of the tubers of the dahlia and artichoke and of the fleshy roots of chicory. It is often found associated with starch in monocotyledonous plants, such as many species of _Iris_, _Hyacinthus_, and _Muscari_. Among the monocotyledons, starch seems to be the characteristic carbohydrate reserve of aquatic, or moisture-loving, species, while inulin is more common among those which prefer dry situations. Inulin may be prepared from the tubers of dahlias or artichokes, by boiling the crushed tubers with water containing a little chalk (to precipitate mineral salts, albumins, etc.) filtering and cooling the filtrate practically to the freezing point, which precipitates the inulin. Inulin is a white, tasteless, semi-crystalline powder, which is soluble in hot water, from which it may be precipitated by alcohol or by freezing. It forms no paste like that of starch or dextrin, and gives no color with iodine. It is levorotatory, and when hydrolyzed by acids or by the enzyme _inulinase_ yields fructose; in fact, inulin bears the same relation to fructose that starch does to glucose. =Graminin, irisin, phlein, sinistrin, and triticin= are all inulin-like polysaccharides, which have been found in the plants after which they are named. Their solutions are, as a rule, sticky or gummy in consistency, which suggests that these compounds bear the same relation to inulin that dextrins do to starch. (C) MANNOSANS, OR MANNANS