lie | idl 
NON-PROTOPLASMIC CELL CONTENTS 79 
tric (apparently ending in the margin of the grain and not sur- 
rounding the hilum), or both, as in potato starch. 
7. The color of the grains when stained with dilute iodine 
solutions; whether indigo, blue, purple, red or yellowish-red, etc. 
8. The appearance under polarized light. 
9. The temperature at which the paste is formed. 
10. The consistency of the paste. 
11. Whether the grains are unaltered or altered. * 
CHARACTERISTICS OF IMPORTANT COMMERCIAL STARCHES 
- Poratro STARCH (Solanum tuberosum) 
Mostly simple, conchoidal or ellipsoidal, 
with occasional spheroidal and two- 
to three-compound grains. 
size:'6 to 125. 
Hilum: circular, at smaller end of grain. 
Lamellz: concentric and eccentric. 
Polarization cross very distinct; beau- 
tiful play of colors with selenite plate. 
MARANTA STARCH (Maranta 
arundinacea) 
Ellipsoidal to ovoid. 
Simple. 
Size: mostly 10 to 65z. 
Hilum: a transverse or crescent-shaped 
cleft in center or near broad end of 
grain, or circular. 
Lamellz: usually faint, concentric and 
eccentric. j 
Polarization cross very distinct; fine 
play of colors with selenite plate. 
Corn Srarcu (Zea Mays) 
Polygonal to rounded. 
Up to 354. Most grains over 15 in 
diameter. 
Simple. 
Hilum: circular or a two- to five-rayed 
cleft. 
Lamellz: indistinct. 
Polarization cross distinct but no 
marked play of color with selenite 
plate, 
* Starch grains may be altered by heat, press 
starch is starch altered by boiling. It gives a sky bl 
Rice STARCH (Oryza sativa) 
Polygonal. 
2 to 10u in diameter. 
Simple or two- to many-compound. 
Hilum: usually indistinct, occasionally 
a central cleft. 
Lamellz: indistinct. 
Polarization cross distinct but no play 
of colors with selenite plate. 
WHEAT STARCH (Triticum sativum) 
Circular grains appearing lenticular 
shaped on edge view; simple. 
Large grains 28 to 45u in diameter. 
Hilum: central, appearing as dot, but 
usually indistinct. 
Lamellz: generally indistinct, when 
present in partially germinated 
wheat, concentric. 
Polarization cross indistinct; no play 
of colors with selenite plate. 
Rye Srarcu (Secale cereale) 
Grains having a similar shape to those 
of wheat starch but many larger; 
simple. 
Large grains 25 to 64y in diameter. 
Hilum: a star-shaped central cleft or 
indistinct in most grains. 
Lamellz: indistinct; concentric in partly 
germinated rye. 
Polarization cross distinct. 
, acids and enzymes. Soluble 
ue color with iodine water. See 
also dextrin, p. 82 and corrosion starch, p. 102. 
