65 



BARLEY. 



1. Size. Two sizes of grains occur; large ones 20 — SOju in 



diameter, small ones less than 7/x in diameter. 



2. Form. Large grains irregularly circular. 



Small grains circular. 



a. Not in aggregates. 



3. Laminae. Indistinct or lacking. 



a. Sometimes cleft. 



4. Hiluni. Indistinct or lacking. 



5. Polarization Crosses. Distinct. 



6. Selenite Plate. Faint play of colors. 



IV. ELLIPSOIDAL STARCH GRAINS. 

 A BEAN (Common) 



1. Size. Grains usually 15 — 60^ in length, (rarely 60/^.) 



2. Form. Ellipsoidal or kidney shaped in case of larger 



grains. 



3. Laminae. Usually distinct. 



4. Hiluni. Elongated. 



a. Branching cleft conspicuous. 



5. Polarization Crosses. Brilliant distinct crosses. 



6. Selenite Plate. Fine play of colors. 



B PEA. 



1. Size. Grains usually less than 40At in diameter. 



2. Form. Ellipsoidal or roundly ellipsoidal. 



a. Rounded protuberances often present. 



3. Laminae. Distinct. 



4. Hilum. Elongated. 



a. Seldom distinctly cleft. 



5. Polarization Crosses. Brilliant crosses. 



6. Selenite Plate. Play of colors. 



C LENTIL. 



1. Size. Grains usually less than 30/i in diameter. Few 



40m. 



2. Form. Ellipsoidal. 



a. Very few grains have protuberances. 



