138 TRANSIT J (>.\ TO A.\A IJR0BI0SI8 



established: (A) That the end products characteristic of 

 anaerobic processes or incomplete oxidations, such as, 

 organic acids, have accumulated in the body, or have been 

 excreted into the medium. (B) That the rate of carbo- 

 hydrate consumption has increased beyond that prevail- 

 ing at normal tensions. A considerable increase in the 

 consumption of carbohydrates, the common mother-sub- 

 stance for fermentations, must be expected because fer- 

 mentations, as a rule, yield very small amounts of energy. 

 (C) That the respiratory quotient is higher than normal. 

 When values above 1.0 are reached, it is evident that some 

 carbon dioxide has been evolved which cannot be account- 

 ed for by the oxygen consumed. (D) That an oxygen 

 debt has been incurred during the period of stay in the 

 oxygen-poor surroundings, as evidenced by an oxygen in- 

 take greater than usual after restoration of a normal 

 oxygen tension. The surplus oxygen is used to eliminate 

 non-oxidized or partially oxidized products formed dur- 

 ing the preceding period of partial asphyxiation. 



Anaerobic oxidations may become necessary to an or- 

 ganism if the distribution of oxygen to the various parts 

 of the body is impaired or if the mechanisms of aerobic 

 oxidations are otherwise impeded: (A) through the ac- 

 tion of poisons like carbon monoxide, cyanide, etc., or (B) 

 by the concentration of salts in the medium. Accord- 

 ingly, two methods of experimentation were developed 

 which, in some cases, contributed valuable evidence of 

 anaerobiosis and will be treated separately below. 



But before considering these various points of evi- 

 dence for a partial transition from aerobic to anaerobic 

 processes we shall review the more general problem of 

 the influence of oxygen tension on oxygen consumption. 



