142 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



with increasing size, while the exchange per unit surface shows only 

 irregular variations without any marked tendency. 



Loewy [Op.] has given another table of comparisons which, when 

 reduced to calories per twenty-four hours, and after exclusion of the 

 values for the ox and the sheep, which are not comparable with the 

 rest, is as follows : 



TABLE XL. 



To conclude from this table that the respiratory exchange of 

 different warm-blooded animals is approximately proportional to the 

 surface area would be rash indeed. 



The most reliable comparisons are undoubtedly those made by 

 E. Voit [1901]. He compares first series of determinations made on 

 each species in the Pettenkofer apparatus. The animals had fasted for 

 one or more days l before the experiments and were quiet during the 

 determinations. For each species the metabolism is carefully reduced 

 to unit surface (square metre) by means of the complete formula 

 given on p. 133 and the specific constant. 



TABLE XLI. 



It must be admitted that the metabolism per square metre is fairly 

 constant. Voit puts forward as an explanation of the low value found 



1 The experiments on the horse are an exception from this rule. They were made by 

 Zuntz and Hagemann [1898] on horses during digestion, and a correction has been applied 

 for the resulting increase in metabolism. This correction appears somewhat arbitrary. 



