76 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



decrease with both higher and lower oxygen percentages. His 

 methods were not nearly accurate enough, however, to demonstrate 

 this. 



As pointed out by Benedict and Higgins most of the experiments 

 made are not accurate enough to decide whether or not there is a 

 slight increase in the oxygen absorption at high oxygen pressures. 

 Loewy [1895] found a slight increase (Table V) when he averaged 

 his figures, but he does not think it real and a calculation of the 

 mean errors shows that it cannot be relied upon. 



TABLE V. 



The most accurate determinations are those made by Benedict 

 and Higgins which show as averages for a large number of experiments 

 on six different subjects the results detailed in Table VI from which 



TABLE VI. AVERAGE ABSORPTION OF OXYGEN IN EXPERIMENTS WITH VARYING 

 OXYGEN TENSIONS (c.c. per minute). 



it is concluded by the authors that the oxygen rich mixtures have no 

 effect whatever on the respiratory exchange. It is extremely probable, 

 however, that there is in these experiments a slight systematic error 

 because the experiments were made with the closed-space apparatus 

 (fig. 1 6) without any introductory period. When an oxygen rich 

 mixture is breathed some oxygen will therefore simply be used to 

 saturate the blood at the higher oxygen pressure, but on the other 

 hand nitrogen will be washed out from the blood and tissues into the 



