DISCUSSION ON BACTERIAL RESPIRATION 267 



complishment is somewhat lessened by our recognition that we can 

 do Httle with the extract that we have not already done with intact 

 resting and acetone-treated cells. Nevertheless, we continue studies 

 with it in the hope that a clue to the mechanism of nitrogen fixation 

 may be furnished by the extract that has been successfully hidden in 

 the intact organism. Meanwhile, however, the physical-chemical 

 studies on the intact growing bacteria will not be neglected, since 

 they have already proved their value. 



REFERENCES 



1. BuRK, D., Ergebnisse d. Enzymforschung, 3, 23 (1934). 



2. Wilson, P. W., The Biochemistry of Symbiotic Nitrogen Fixation (University 

 of Wisconsin Press, 1940 ) . 



3. BuRK, D., and Burris, R. H., Ann. Rev. Biochem., 10, 587 (1941). 



