CELL CONTENTS S15 
Cystoliths occur, then, in special cavities, in parenchyma 
cells (rubber-plant leaf, fig, pellionea, and mulberry), and in 
non-glandular hairs (cannabis indica). 
In powdered ruellia root the cystoliths occur in or are sepa- 
rated from the parenchyma cells. 
TESTS FOR CYSTOLITHS 
When dilute hydrochloric acid or acetic acid is added to 
cystoliths a brisk effervescence takes place with the evolution 
of carbon dioxide gas. 
