70 VEGETABLE HISTOLOGY. 



OTHER STARCHES. 



MARANTA. A large proportion of the edible starches obtained 

 from the rhizomes or root-stocks of various plants are known 

 in commerce under the name of arrow-root. Properly the name 

 should be restricted to the starch yielded by two or three species 

 of Maranta, the chief of which is Maranta arundinacea. Ac- 

 cording to the country from which it is derived, maranta starch 

 is known as Bermuda, St. Vincent, West Indian or Natal arrow- 

 root. The grains are simple and mostly ovoid, the largest ones 

 being marked by fine striations, but less distinct than those of 

 potato starch. The nucleus is rounded, linear or star-shaped 

 and usually placed eccentrically. The grains are rather large, 

 but smaller than potato starch. 



TOUS-LES-MOIS, Tulema or Queensland arrow-root is obtained 

 from several species of canna, a genus closely allied to maranta. 

 The grains resemble those of potato starch, but are much larger. 



CURCUMA or East Indian arrow-root is obtained from the 

 root-stocks of several species of the genus Curcuma (Zingi- 

 beracea?) chiefly Curcuma angustifolia. The grains are ovate 

 and taper to a nipple-like projection at one end, in which the 

 hilum is located. The grains are simple, rather large and so 

 flat that on edge they seem rod-shaped (Fig. 43, VIII). Ginger 

 starch is shaped somewhat like that of curcuma. 



BRAZILIAN arrow-root, cassava, or tapioca of commerce, is 

 manufactured from the starch obtained from the tubers of 

 Manihot utilissima. Most of the grains are blurred, which is 

 due to the heating in the process of manufacture, but many 

 grains may be found uninjured. Soak some of the starch a 

 few hours in water, mash a little out on a slide in water, cover 

 and examine. The unchanged grains appear as in Fig. 43, IX; 

 the others are more or less gelatinized. 



BRITISH arrow-root is potato starch, which is sometimes sold 

 under this name. The French excel in the preparation of imi- 

 tations of the more costly starches from potato starch. Its 

 chief use, however, as an edible starch, is for adulterating other 

 more costly preparations. It can easily be distinguished under 

 the microscope. 



SAGO, or pearl sago, of commerce is obtained by heating and 

 stirring the moist starch of the sago palm, Metroxylon Sagu. 

 As in the case of tapioca, many of the grains are gelatinized, 

 but some are still intact, which appear as in Fig. 43, X. 



MAIZE or corn starch is obtained from the fruits of Zea Mays. 

 The grains are simple, rounded or polygonal and tolerably uni- 

 form. The hilum appears as a point or more often as a stellate 

 cleft, less frequently as a large central cavity. This starch ia 

 one of the most frequently used adulterants of powdered 

 articles, and hence should be closely studied. 



