M. H. SOULE 267 



It is apparent that relatively simple apparatus and methods are now available 

 for the exact determination of the gaseous metabolism of bacteria. When applied to 

 aerobic forms, the amount of O2 consumed and of CO2 produced can be readily as- 

 certained. By contrast, the anaerobic organisms yield relatively large volumes of 



CO2 

 gases which consist essentially of CO2 and H2. The hydrogen quotientj-r^r^ , may pos- 



sibly be useful as a basis of classification. 



