1912.] Glucose of Bacillus coli communis (JEscherich). 417 



(3) C 6 H 12 6 + H 2 = C 2 H 4 2 + C 2 H 6 + 2HC0 2 H 



= C 2 H 4 2 + C 2 H 6 + 2C0 2 + 2H 2 . 



These enzymes may occur in different proportions in different individual 

 organisms, and the process of selection would then result in the survival 

 of an organism containing a large proportion of the lactic acid enzyme 

 and a small proportion of that producing alcohol, acetic acid, and formic 

 acid. It may be noted that the selected organism still retains the power 

 of decomposing formic acid into C0 2 and H 2 , and, moreover, its products 

 do not contain more of this acid than those of the normal bacillus. The 

 absence of gas formation, therefore, is not due to an accumulation of 

 formic acid. It is thus seen that the change produced in the organism 

 does not really cause its chemical action to approximate to that of B. typhosus, 

 an organism which also yields no gas, but differs from B. coli by producing 

 a large amount of formic acid. 



The foregoing numbers are not sufficiently accurate to decide with 

 certairity whether the relative proportions of alcohol, acetic acid, and formic 

 acid produced by the selected organism are the same as those formed by 

 the original bacillus. Taking the alcohol as standard, the carbon as formic 

 acid (including gaseous C0 2 ) should be 0-27, instead of - 22 observed, and 

 that as acetic acid 041 instead of 0'6. The deviation in the last case 

 may be due to the difficulty of effecting the quantitative separation of acetic 

 acid from a large proportion of lactic acid. 



Further experiments may be expected to throw light on these points. 



If, however, the foregoing explanation be found correct, the study of 

 the chemical action of these selected organisms should form a valuable 

 means of investigation into the nature of the various processes of fermenta- 

 tion effected by bacteria, and the subject is being prosecuted from this point 

 of view. 



REFERENCES. 



(1) Penfold, 'Eoy. Soc. Med. Proc.,' 1911, p. 97. 



(2) ' Biochemical Journal,' 1910, vol. 5, p. 230. 



(3) Harden, 'Chem. Soc. Journ.,' 1901, p. 610. 



2 G 2 



