The term _hilum_ has come to have a broader meaning than formerly. Hilum includes at the present time not only the starting-point of the starch grain, but the fissures which form in the grain upon drying. In all cases these fissures originate in the starting-point, hilum, and in some cases extend for some distance from it. The hilum, when excentral, may occur in the broad end of the grain, galanga, and geranium (Plate 71, Figs, 1 and 3), or in the narrow end of the grain, zedoary (Plate 71, Fig. 4). NATURE OF THE HILUM The hilum, whether central or excentral, may be rounded (Plate 75, Fig. 1); or simple cleft, which may be straight (Plate 71, Fig. 1); or curved cleft (Plate 71, Fig. 2); or the hilum may be a multiple cleft (Plate 74, Fig. 3). In studying starches use cold water as the mounting medium, because in cold water the form and structure are best shown, and because there is no chemical action on the starch. On the other hand, the form and structure will vary considerably if the starch is mounted in hot water or in solutions of alkalies or acids. The hilum appears colorless when in sharp focus, and black when out of focus. Starch grains, when boiled with water, swell up and finally disintegrate to form starch paste. Starch paste turns blue upon the addition of a few drops of weak Lugol solution. Upon heating, this blue solution is decolorized, but the color reappears upon cooling. If a strong solution of Lugol is used in testing, the color will be bluish black. [Illustration: PLATE 72 STARCH 1. Orris root (_Iris florentinia_ L.). 2. Stillingia root (_Stillingia sylvatica_, L.). 3. Calumba root (_Jateorhiza palmata_, [Lam.] Miers.).] [Illustration: PLATE 73 STARCH 1. Male fern (_Dryopteris marginalis_, [L.] A. Gray). 2. African ginger (_Zingiber officinalis_, Rosc.). 3. Yellow dock (_Rumex crispus_, L.). 4. Pleurisy root (_Asclepias tuberosa_, L.).] [Illustration: PLATE 74 STARCH 1. Kava-kava (_Piper methysticum_, Forst., f.). 2. Pokeroot (_Phytolacca americana_, L.). 3. Rhubarb (_Rheum officinale_, Baill.).] [Illustration: PLATE 75 STARCH GRAINS 1. Bryonia (_Bryonia alba_, L.). 2. Belladonna root (_Atropa belladonna_, L.). 3. Valerian root (_Valeriana officinalis_, L.). 4. Colchicum root (_Colchicum autumnale_, L.).] [Illustration: PLATE 76 STARCH MASSES 1. Aggregate starch of cardamon seed (_Elettaria cardamomum_, Maton). 2. Aggregate starch of white pepper (_Piper nigrum_, L.). 3. Aggregate starch of cubebs (_Piper cubeba_, L., f.). 4. Aggregate starch of grains of paradise (_Amomum melegueta_, Rosc.).] INULIN =Inulin= is the reserve carbohydrate material found in the plants of the composite family.