RESPIRATORY EXCHANGE IN DIFFERENT ANIMALS 141 



Comparison between Different Species of Warm-blooded 



Animals. 



For comparisons between different warm-blooded animals series 

 of sufficiently reliable experiments made under truly standard con- 

 ditions are not available, and the comparisons have to be made 

 between experiments made by different experimenters using different 

 methods, usually at different temperatures and with only scanty in- 

 formation about the state of the animals. Tables can be put together, 

 therefore, which will satisfy almost any theory which could be put 

 forward. 



Tigerstedt [W.] has given the following table showing the 24- 

 hour metabolism of fasting animals, to which I have added the last 

 column : 



TABLE XXXIX. 



It should be remarked that while the figure for man is standard 

 metabolism, the other results have been obtained on animals which 

 were more or less quiet in the ordinary sense. This does not even 

 apply to the mouse or to the small birds which are never really 

 quiet when awake. When these things are taken into account the 

 table shows that the respiratory exchange per unit weight falls regularly 



