60 



ACIDITY AND GAS INTERCHANGE IN CACTI. 



TABLE 37. Wound respiration. 



The normal respiration was first determined, and the plant then wounded by slicing 

 joints into sections 10 to 15 mm. thick. The determinations were made in New York 

 with the Pettenkofer apparatus, the material being 8 joints of Opuntia versicolor having a 

 fresh weight of 170 gm., sent from Tucson, Arizona. The date of the experiment was 

 April 5 to 9, 1912. 



