DESCRIPTION OF PLATE II 



Fig. s.— Types of Crystals of Calcium Occurring in Different Plants.— i. A 



parenchyma cell containing a bundle of needle shaped (acicular) crystals of calcium 

 oxalate (raphide). 2, 3, 4, Acicular crystals differing in length, as they occur in 

 Scilla and in other representatives of the liliaceous groups of plants. 5. Much 

 elongated prismatic crystals as they occur in QuiUaja and in Iris florentina. 6. 

 Prismatic crystals very widely distributed in the plant kingdom. 7. Elongated 

 prismatic crystals. 8. Twin crystals as they occur in Ulmus bark. 9. Very large 

 aggregate crystals as they occur in Rheum and Polygonum species. 10, 11. Smaller 

 aggregate crystals very widely distributed in the vegetable kingdom. 12, 13. Very 

 minute prismatic (pyramidal) crystals as they occur in Belladonna. 14. Prismatic 

 crystals as they occur in Hyoscyamus and in other plant groups. 



Calcium oxalate crystals are among the highly diagnostic structural characteris- 

 tics of drug plants and should be studied not only as to form but also as to size. 

 They are not dissolved in the usual mounting media and are not destroyed by heat. 

 They dissolve slowly in the stronger acids (hydrochloric acid). 



Fig. 6. — ^Types of Bast Cells as They Occur in Barks and in Other Plant 

 Parts. — I. Shorter bast cell as they occur in the cinnamon barks. 2. Typical 

 bast cell (showing a portion of a cell only) as they occur in willow bark, in Ulmus, in 

 Mezereon, etc. 3. Branching bast cells as they occur in QuiUaja and in Prunus 

 bark. 4. Greatly thickened sclerenchymatous bast cells as they occur in the 

 Cinchonas. 



Fig. 7. — Types of Sclerenchyma (Stone) Cells. — i. Typical sclerenchyma cells 

 as they occur in the endocarp of drupaceous fruits and nuts. 2. Elongated bast- 

 like sclerenchyma cells. 3. Thin- walled typical sclerenchyma cell. 4. Scleren- 

 chyma cell with unequally thickened walls as they occur in the cinnamons. 5. 

 Large thin-walled sclerenchyma cells as they occur in the seed coat of Amygdala. 



6. Branching sclerenchyma cells as they occur in tea leaves and in peanut exocarp. 



7, 8, 9. Forms of sclerenchyma cells. 



Fig. 8. — Typical Sclerenchyma Cells (in groups) as they occur in the pulp of 

 the pear. 



