152 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



The production of an inactive or active modification depended 

 in this case on the organism. With different conditions of 

 experiment different results are obtained, and the production 

 of a dextro or laevo form depends quite as much on the 

 fermenting medium as on the organism producing the fermen- 

 tation. The dependence of the products of the reaction upon 

 the constitution of the fermenting molecule has been the 

 subject of a very interesting research by Harden, who has 



FIG. 24. APPAEATUS USED IN DR. HARDEN'S EXPERIMENTS ON 

 B. coli communis. 



studied the chemical action of B. coli commums and similar 

 organisms on carbohydrates and allied compounds. 



The apparatus shown in Fig. 24 was made use of ; one litre 

 of the solution was placed in a large flask provided with a 

 side tube and an indiarubber stopper, through which passed a 

 straight glass tube leading to the bottom of the flask, the side 

 tube and vertical tube were plugged with cotton wool and the 

 flask then sterilised. The side tube was then attached to a 

 piece of bent tubing (A) on which a small bulb was blown near 

 tjie bend ? a drop of mercury was placed in the tube and served 



