DISCUSSION ON BACTERIAL RESPIRATION 265 



the problems with which we are confronted in extracts and in Hving 

 cells: 



1. In extracts a disturbance of the ratio of the various components 

 and an effect upon the total enzyme system occurs automatically, 

 which may cause an accumulation and even a stabilization of tran- 

 sient products. 



2. By selective poisoning of parts of the enzyme system numerous 

 facts have been established. 



3. In hving cell processes, because of the introduction of reagents 

 not akin to the whole system, a supposed or possible intermediary 

 product is removed and thereby excluded from the reaction se- 

 quence. For example: 



1. Amino acid oxidase is capable of deaminating I- or d-amino 

 acids in tissue slices. In the case of injured or denatured tissues, 

 however, natural amino acids are no longer deaminated. 



2. The extent to which the carrier enzymes are dispersed may 

 change under the influence of various factors. Moreover, in the cells 

 disperse particles of the various protoplasmic substances actually 

 possess widely differing pH values. 



3. Even Dr. and Mrs. Cori declare, in accordance with the afore- 

 mentioned fact, that the conditions for glycogen synthesis are much 

 more favorable in the intact cell than in tissue extracts, where, they 

 state, they have obtained starch.* 



4. Experiments show that in the case of Corynebacterium diph- 

 theriae, strains gravis and mitis, conditions are comparable. 



5. There is no stoichiometrical relationship between the carbon 

 dioxide evolved and the actual decrease in inorganic phosphorus 

 (in the living cell). 



6. When carbon dioxide evolution was compared with energy 

 liberated as heat by living yeast cells and by Lebedew extract, it 

 was noted that the heat of reaction in the course of fermentation 

 changed continually, indicating that fermentation with living cells 

 does not proceed according to a fixed scheme. 



The thermochemical course of fennentation with juices shows, in 

 contrast, that at least two different conversions occur: (1) fermenta- 

 tion of free sugar in the presence of free phosphate (inhibited by 

 phloridzin) and (2) the subsequent fermentation of the residual 

 substrate in the absence of free phosphate (not inhibited by phlorid- 

 zin). 



* Compare G. J. Goepfert, Brewers Digest, 16, No. 6 (1941). 



