EXPERIMENTAL DATA OF DETERMINATIONS WITH PETTENKOFER 



APPARATUS. 



TABLE 28. Respiration and acidity of young, mature-turgid, and mature-flaccid 

 joints of Opuntia versicolor at various temperatures. 



The determinations were made in half-hour periods and the results are the averages of 

 these, estimated in terms of milligrams of CO 2 per hour. The number of periods from which 

 the averages were made is indicated in the fifth column. No determinations were made 

 until the material had been at least 1$ hours at the temperatures named. The acidities 

 given were made from parallel material at the close of each temperature period, except the 

 acidities at 45 C., which were from the material used in the COz determinations. The 

 experiments were made at Tucson, Arizona, in June and July 1912. 



55 



