68 



4. Hilum. Distinct. Excentricity 1-3 — 1-5. 



a. Often crossed by clefts. 



5. Polarization Crosses. Distinct. 



6. Selenite Plate. Fine play of colors. 



F MARANTA. 



1. Size. 30 — 50/x long, (seldom larger.) 



2. Form. Similar to potato, pear-shaped; also broad, 



spindle-shaped grains always present. 



3. Laminae. Usually distinct. 



4. Hilum. Distinct, in broad end of the grain. 



a. Usually cleft by curved, wing-like fis- 

 sures. 



5. Polarization Crosses. Distinct, striking. 



6. Selenite Plate. Beautiful play of colors. 



G YAM. 



1. Size. Grains range in size from 30 — 60yu in length. 



Seldom the latter. 



2. Form. Irregular, ovate, reniform. 



a. Often segmented at broad end. 



b. End not pointed. 



3. Laminae. Distinct evident. 



• 4. Hilum. Distinct, circular in narrow end of grain. 

 Excentricity 1-5 — 1-7. 



5. Polarization Crosses. Distinct. 



6. Selenite Plate. Play of colors. 



H BANANA. 



1. Size. Grains usually 20— 40/x long. Occasionally larger 



grains are found. 



2. Form. Cigar-shaped, rod-shaped, irregular-ellipsoidal. 



a. Occasionally aggregates of two grains, 

 end to end, form sickle shaped bodies. 



3. Laminae. Very distinct. 



4. Hilum. Distinct, usually in broad end of grain. 



a. Rarely found in narrow end. 



5. Polarization Crosses. Distinct. 



G. Selenite Plate. Play of colors evident. 



