W. J. V. OSTERHOUT 179 



CO2 and HoO. The consumption of O2 and the production of CO2 

 furnish the most convenient means of measuring respiration and it is 

 always desirable to study both together. If we find that O2 is con- 

 sumed but no CO2 is produced, as in some of Warburg's experiments/^ 

 we may speak of respiration. If on the other hand CO2 is produced 

 but no free O2 is consumed, as is the case in anaerobic respiration, 

 we may regard this as respiration also. Ordinarily a rise in the rate 

 of CO2 output is interpreted as a rise in the rate of respiration, but 

 it might happen that the sudden production of an acid (e.g. lactic 

 acid) might set free CO2 from carbonates already present in the tissue. 

 When there is reason to suspect that this is the case special precau- 

 tions must be taken to ascertain how the CO2 is produced. 



Some writers endeavor to make a distinction between oxidation 

 in the living cell and that which occurs after death. In the opinion 

 of the writer there is no valid ground for such a distinction, and the 

 term respiration is here used to include processes which occur imme- 

 diately after death. 



SUMMARY. 



A series of investigations on respiration with improved quantita- 

 tive methods has been commenced. The first of these are here de- 

 scribed. They show that when anesthetics are employed in sufficient 

 concentration to produce any result, plants show a rise in the rate of 

 respiration which is followed by a fall. In the animals studied, the 

 rise (found in higher concentrations only) was preceded by a tempo- 

 rary fall which is not entirely due to lowering of muscular activity or 

 tonus. In lower concentrations the effect on animals was merely a 

 decrease of respiration. 



The results of all the investigations are opposed to the theory of 

 Verworn. 



^^ Warburg, Ergebn. Physiol., 1914, xiv, 319. 



