190 



STUDIES ON EESPIRATION. II 



RATE 



180% 



100 



-it—^f 



~ ^~-~— f— 



60MIN. 



Fig. 5. Curve B shows the respiration of Aspergillus niger, first for 20 min- 

 utes in tap water (horizontal part of curve), then in 20 per cent acetone. Curve 

 A shows the respiration, first in tap water (horizontal part of curve), then in 0.5 

 per cent solution of caffeine. Curve C shows respiration, first in tap water (hori- 

 zontal part of curve) , then in saturated solution of caffeine. The dotted line shows 

 the respiration of a control in tap water. 



The normal rate (which is taken as 100 per cent) corresponds to a change 

 from pH 7.60 to pH 7.25 in 2.75 minutes for Curve A; in 3.25 minutes for Curve 

 B, and in 3 minutes for Curve C. 



Curve A represents the average of seven. Curve B of four, and Curve C of 

 two experiments. Probable error less than 2.4 per cent of the mean. 



