244 RECOVERY FROM ANAEROBJO^hS 



the post-anaerobic oxygen consumption on the tension 

 is only a special instance of the rule that any increase 

 in the respiratory rate will shift the critical oxygen ten- 

 sion at which the oxygen consumption begins to de- 

 cline, tow^ards a higher level. One could make a com- 

 parative study of the two opinions by investigating the 

 relationships between the rate of oxygen consumption 

 and the tension tirst in normal animals, kept, previous to 

 the determinations, in well-aerated surroundings, then in 

 *' post-anaerobic" animals, and finally, in normal animals 

 exposed to respiratory stimulants {e.g., methylene blue, 

 para-phenylene-diamine and others). If von Budden- 

 brock's view is correct the last group should show a curve 

 similar to that of post-anaerobic animals ; if Harnisch is 

 right, it ought to resemble more that of the normal ani- 

 mals. 



B. Production and retention of carton dioxide, and the 

 respiratory quotient. Regardless of whether or not the 

 actual recovery processes result in the production of 

 carbon dioxide, this gas is always formed during a post- 

 anaerobic period. This is explained by the generally ac- 

 cepted view that the normal aerobic metabolism is re- 

 sumed as soon as oxj'gen becomes available. It would, 

 then, proceed side by side with the special reconstitution 

 reactions. Rarely, however, if ever, is all the produced 

 carbon dioxide actually excreted; a certain amount is 

 usually retained and used to rebuild bicarbonates and 

 carbonates destroyed during the anaerobic period. 



The carbonate reconstruction requires, in most cases, 

 a few hours, but the period of carbon dioxide retention 

 does not always coincide exactly with that of excess oxy- 

 gen consumption. As a rule, both seem to begin imme- 

 diately upon the restoration of aerobic conditions, 

 though there are exceptions. In snails (Dahr, 1927) the 

 oxygen consumption is first at a low level, but it finally 

 rises to high values. In Zootermopsis the carbon diox- 



