224 



Comparative Animal Physiology 



as temperature affect the rate of oxygen consumpti i. Gas exchange is not the 

 only index of activity or energy production of an organism, but its correlation 

 in a quantitative way with rate of metabolism and heat production has made 

 it the generally accepted standard of the over-all measuic of metabolic 

 processes. 



The Determination of Oxygen Consumption It is unnecessary to discuss 

 here in detail the many methods and their uses that have been elaborated by 



^ a 



Fis- 44. Respiromctcrs developed by (a) Warburg,'"'' (b) Fenn,"" (c) Scholander 

 and Edwards,"'' and (d) Holter and Linderst^t^n-Lang.'™ 



a host of investigators in the held. Ihe monographs of Dixon'''" and Krogh,-'^ 

 as well as I Iciibrunn's tcxt,"'"'^ Umbreit's handbook, -'^"^ and, if micromethods 

 are desired, the important review by robias,''^-'' should be consulted for ex- 

 tensive bibli()gra]-)hics as well as discussions of principles, sensitivities, and 

 limitations in\'()l\ cd in the \arious techniques that haxe been devised. I he 

 earlv literature was abl\ summarized bv liuerstedt.''"'^ 



