236 RECOVERY FROM ANAEROBIOSJ^"^ 



It may be mentioned, finally, that animals exposed to 

 respiratory poisons, like hydrocyanic acid, behave much 

 like those directly deprived of oxygen. The revival of 

 insects after exposure to such poisons has received con- 

 siderable attention in connection with fumigation prob- 

 lems. It would lead us too far afield to review here the 

 data accumulated in the literature of applied entomology. 

 The reader is referred to the thorough papers of Bliss 

 (1935), and of Broadbent and Bliss (1936), on Drosophila, 

 among others. 



2. POST-ANAEROBIC GAS EXCHANGE 



Any animal in which the oxidations are normally 

 aerobic will, when deprived of oxygen, experience a need 

 for this gas, resulting in an oxygen debt. Whether and 

 to what extent this debt is repaid during the subsequent 

 exposure to air depends upon whether or not non-oxi- 

 dized substances have accumulated in the body and also 

 upon the chemical nature of the recovery processes. This 

 is obvious since any excess oxygen is used to remove, by 

 aerobic oxidations, the accumulated end products of the 

 anaerobic metabolism. Another very frequent feature of 

 the recovery respiration is the retention of carbon diox- 

 ide. We have mentioned previously that the liberation 

 of carbon dioxide from inorganic substances is a common 

 phenomenon in anaerobic metabolism. These substances 

 — bicarbonates or carbonates — are rebuilt during the re- 

 covery period, and this resynthesis obviously requires 

 carbon dioxide. In all cases of retention, pronounced 

 changes in the respiratory quotient must occur. We shall 

 discuss post-anaerobic respiration in two sections, the 

 first one dealing with the oxygen consumption, the sec- 

 ond with the carbon dioxide production and retention, 

 and with the respiratory quotient. 



A. Oxygen consumption. It is clear that, if all the end 

 products of anaerobic metabolism were excreted, no re- 

 payment of an oxygen debt could be expected. It is, 



