156 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



The reaction in the case of mannite would be represented 

 as follows : 



CH 2 OH 



| = CH 3 -CH OH + C0 9 + H 2 



CHOH CH 2 OH 



CHOH CHOH 



! I 



CHOH CHOH 



I I 



CHOH CHOH 



CH 2 OH CHOH 



CH 2 OH 



= CH 3 -CH 2 OH + C0 2 + H 2 



The precise modification of lactic acid which may be 

 produced will, according to this theory, depend on the con- 

 figuration of the three centre CHOH groups and also on the 

 particular organism taking part in the reaction. 



Harden's suggestion as to the dependence of the alcohol 

 formation on the presence of a terminal group CH 2 OHCHOH 

 finds further confirmation in his studies in conjunction with 

 Walpole on the action of B. lactis aerogenes on glucose and 

 mannite. They found that, in addition to the usual products 

 of this class of fermentation, glucose yields butylene glycol, 

 CH 3 CH(OH)CH(OH)CH 3 . Mannite, on the other hand, gives 

 similar products, but less butylene glycol and more alcohol. 



The instances given in the foregoing chapter will suffi- 

 ciently indicate the complexity of the problem involved in 

 obtaining a full explanation of the manner in which carbo- 

 hydrates break down under the action of bacteria. Com- 

 paratively few cases have been worked out in a rigorous 

 manner as in the researches referred to above ; it is, however, 

 only by systematic quantitative work of this kind, with sub- 



