EXPERIMENTAL DATA ON ACIDITY DETERMINATION. 



45 



TABLE 21. Effect of injury on acidity. Opuntia versicolor. 



Shows the effect of injury on acidity in mature joints, turgid from winter rains and 

 injured by slicing into sections 5 to 10 mm. thick, at Tucson, Arizona, March 1911. 

 The sections were kept in moist atmosphere, but with free access of air, and in diffuse light 

 at laboratory temperature 23 to 25 C. Acidity is expressed in terms of cubic centimeters 

 of N /10 KOH per gram fresh weight. 



TABLE 22. Acidity of tissues of different ages. Opuntia versicolor. 



Acidity is expressed in terms of cubic centimeters of N /10 KOH per gram fresh weight. 

 The material was all mature and turgid from the winter rains. The temperature throughout 

 the experiment was 23 to 25 C. The experiments were conducted at Tucson, Arizona, in 

 March 1911. 



TABLE 23. Diurnal periodidty of acidity in Mammillaria grahami. 



Tucson, Arizona, March and April 1911. The acidity is given in cubic centimeters N /10 

 KOH per gram fresh weight. The plants being small, it was necessary to use a separate one 

 for each determination. 



