78 



ACIDITY AND GAS INTERCHANGE IN CACTI. 



TABLE 51. Average of 99 gas-interchange experiments, arranged according to the 



acidity of the pure juice. 



Average of 99 gas-interchange experiments, arranged according to the acidity of the pure 

 juice, and grouped according to temperatures. The acidity is given in terms of cubic 

 centimeters N /10 KOH per cubic centimeter pure juice. The COj and Oj are given accord- 

 ing to cubic centimeters of gas per gram-hour, fresh weight. 



CERTAIN ANOMALOUS CASES. 



In four of the experiments carried out at Tucson during 1912 and 1913 there 

 was an entire or practically entire cessation of carbon dioxide evolution. 

 These must be regarded as anomalous, for they stand out sharply from all the 

 others. The lowest gas ratio cited, that of 0.29, where the amount of gas 

 produced was greatly diminished, is hardly comparable with the condition 

 of gas interchange found in these instances. The experiments in question are 

 K' and DD' (table 64), where the amount of carbon dioxide found was minimal 

 and Q', 1, and 17 (table 64), where there was no evolution of carbon dioxide at 



