Formates by B. coli communis. 



471 



Summary and Conclusion. 



(1) The power of B. coli communis to decompose formic acid varies con- 

 siderably when the organism has been kept for some time on artificial 

 media. 



(2) The decomposition of formates is inhibited by a very small excess of 

 either acid or alkali and, therefore, a greatly increased decomposition of 

 formates results if glucose is added, since the acid produced from the sugar 

 neutralises the alkali from the formate. 



(3) A method and apparatus are described by which the decomposition of 

 various substances by micro-organisms may be followed quantitatively 

 requiring only 50-100 c.c. of the solution. 



(4) It has been suggested that in place of a solution of sodium formate a 

 mixture of sodium formate - 5 per cent, and glucose 1*5 per cent, should be 

 used as a test of a gas-producing strain, since by this means the production 

 of gas from formate is greatly increased, and it is also suggested that the test 

 could be used as a criterion as to whether an organism, which has been 

 recently isolated from some natural source and produces no gas from glucose 

 peptone water, may be regarded as having been recently derived from a gas- 

 producing strain. 



(5) It has been shown that formates may be conveniently used as 

 neutralising agents, and that thereby the activity of gas-forming organisms 

 may be considerably increased. 



In conclusion I would express my thanks to Prof. Harden, F.K.S., for help 

 and criticism. 



EEFERENCES. 



Arkwright. J. A., ' Journ. Hyg.,' vol. 13, p. 68 (1913). 



Grey, E. C, this vol., p. 472 (1914). 



Harden, A., 'Chem. Soc. Journ.,' vol. 79, p. 610 (1901). 



Harden, Thompson and Young, ' Biochem. Journ.,' vol. 5, p. 230 (1910). 



Harden and Penfold, W. J., 'Proc. Roy. Soc.,' B, vol. 85, p. 416 (1912). 



Penfold, W. J., ' Roy. Soc. Med. Proc.,' p. 97 (1911). 



Pakes and Jollyman, 1 Chem. Soc. Journ.,' vol. 79, p. 386 (1901). 



VOL. LXXXVII. — B. 



