Decomposition of Organic Compounds. 261 



Saccharomyces cerevisice and certain species of bacteria were grown in nutrient 

 media, and the chemical action of their vital processes was utilised to develop 

 electrical energy in a manner parallel to the production of E.M.F. by means 

 of the ordinary galvanic cell. 



The Apparatus. 



The apparatus employed (fig. 1) consisted of a glass jar containing a porous 

 cylinder. The same nutrient fluid was placed in the glass jar and in the 

 porous cylinder, and two platinum electrodes were introduced, one into the 



A, The ceJl. 



E, Galvanometer. 



C, Condenser. 



D, Mercury cups to 

 facilitate connections 

 with different cells. 



E, Morse key. 



fluid in the jar and the other into the porous cylinder. In the case of pure 

 cultures, instead of the jar, a large boiling tube was used, which could be 

 plugged with cotton wool and the whole apparatus sterilised either by inter- 

 mittent boiling or in an autoclave. After sterilisation the fluid in the 

 boiling tube could readily be inoculated with the micro-organisms under 

 investigation. Cultures of micro-organisms, when introduced into either the 

 fluid in the jar (the outer fluid) or that in the porous cylinder (the inner fluid), 

 under suitable conditions, set up a chemical action, and the apparatus so far 

 described constitutes a type of galvanic cell. 



Throughout the main experiments platinum was used as the electrode, and 



