Chapter XIV 



— 169 — 



The Vacuolar System 



pounds remain uncolored with the leucoderivative, and the leuco- 

 derivative which they have absorbed becomes oxidized instantane- 

 ously m contact with air. It may therefore be believed that the 

 vacuoles of wheat and Iris are acid whereas those of the bean are 

 not. 



Vacuolar rH has been evaluated by means of vital stains (Ma- 

 TIUJA Brooks) or by micro-injection of indicators in algae such as 

 Spirogyra. These measurements have given an rH of 16-18. 



Fig. 116. — A, Petiole of Begonia; octahedral crystals, 

 isolated (lower cell), or twinned (upper left), in the 

 shape of a sea urchin (upper right). B, Leaf of Aloe 

 succotrina; raphides. 



