ACID ACCUMULATION IN SUCCULENTS 



263 



recorded in the number of cc. of -nr NaOH required to neutralize 

 1 cc. of the sap. 



The increase in acidity in the morning samples is "apparent. 

 This is what is to be expected in view of the greater intensity of 



VlRTICAL 

 StCTlO/1 



/ v 



Vlbtical 



StCTIOM 



Cross - Stc-non 



E.CHIAIOCACTUS 



Cross -Stc-non 



Carnlgie.a 



Fig. 1. Diagram of Echinocactus and Carnegiea in section, showing regions 

 from which samples were taken for analysis. 



light and heat acting upon the plants during the day. Relieved 

 from the destructive action of these agencies, the organic acids 

 which are formed wherever carbohydrates are being burned, 

 tend to accumulate during the night faster than they are de- 



