276 ECONOMIC BOTANY. 



a cavity, ■which is often more or less star-shaped. No com- 

 pound grains intact are found in the rice starch of com- 

 merce. This resembles the starch of oats, but may be 

 distinguished from it at a glance, for in the latter the 

 compound grains are not wanting. 



250. Corn Starch, from grains of Indian Corn 

 (Zea Mays; family Graminece), is much like that of 

 wheat. The paste, however, is thicker, and the starch 

 is more readily converted into grape sugar. "When used 

 in finishing cloth, it does not give so fine a polish as the 

 wheat starch. The grains are perceptible with a strong 

 lens ; the size varies between .00032 and .00122 inches. 

 Some grains are simple, polyhedrical, or roundish. The 

 compound grains are composed of two to five parts. 

 When fresh, they exhibit a nucleus; but when dry a 

 cavity instead. The layers are not often perceptible. 



251. West India Arrow-root, or Maranta Starch, 

 is from the white, scaly, tuberous rhizomes of species of 

 Maranta (family Scitamineas). They are tropical or sub- 

 tropical plants. M. arundinaeea is indigenous in the West 

 Indies and South America ; cultivated in the Burmudas, 

 Guiana, Ceylon, etc. M. indica is indigenous in the East 

 Indies ; cultivated in the East Indies and adjacent islands. 

 The starch has been used by the natives from time imme- 

 morial. It is obtained by washing the rhizomes and soak- 

 ing the pulp in water ; the starch can then be washed out. 

 The size of the grains is variable; the largest diameter 

 .00043-00276 inches. The shape is oval, elliptical, or 

 irregular; the grains are both simple and compound. 

 This furnishes a simple food for invalids. 



252. The East India Arrow-root Starch is from two 

 species of Curcuma (C. angustifolia and C. leucorrhiza'), 



