320 



GASOMETRIC-VOLUMETRIC METHODS 



gas volume changes. The original technique of Kalmus has been the 

 object of considerable criticism, but Cunningham and Kirk (1942) 



Type A Type B 



Fig. 96. Left : two capillary respirometers, shown with 

 protective jackets of glass tubing. Right: respirometer 

 assembly with microscope for observing shift of meniscus. 

 From Cunningham and Kirk (1942) 



have instituted improvements and they have chosen this open-tube 

 instrument in preference to differential types for studies requiring a 

 very high degree of sensitivity, e.g., measurements of the respira- 

 tion of a single Paramecium. The sensitivity obtained by Cunning- 

 ham and Kirk was 5 X 10"^ /^l- While the absolute accuracy is 

 doubtful, the accuracy for relative values was given as at least 

 dzl5% for the instruments used. It should be pointed out that the 

 technical difficulties involved in the use of this type of respirometer 

 are very great, and these will, no doubt, seriously limit its applica- 

 tion. 



Diagrams of the instruments are given in Figure 96; their dimen- 

 sions follow: 



Dimension 



Type A 



Type B 



Volume of liquid phase 



Volume of gas phase 



Diameter of respiration chamber. 



Diameter of manometer 



Length of manometer 



