260 Dr. A. Macfadyen, Dr. G. H. Morris, and Mr. S. Rowland. 



fall in gravity of the juice. These experiments agree with those of 

 Buchner on the same point. 



Table III. Influence of Filtration on the Activity of the Juice. 



* In this experiment the filtration was through a Chamberland filter ; in the 

 remaining experiments a Berkefeld filter was used. 



f After 72 hours in this case ; all the others after 48 hours. 



Influence of Dilution. In considering the nature of the action of the 

 juice and of the agent to which the evolution of gas was due, it 

 appeared important to ascertain the effect of dilution on the action of 

 the juice. All experiments were conducted by adding the weighed 

 quantity of sugar to the juice itself, so that no water at all was intro- 

 duced. If the action were a purely enzymic one, dilution to a limited 

 extent should not appreciably affect the result ; whereas if the action 

 were due to other causes, it might be influenced to a greater or less 

 extent. We accordingly carried out a series of determinations on 

 dilution with water alone, with physiological salt solution (0'75 per 

 cent, sodium chloride), and with water in the presence of cane-sugar. 

 The experiments with sugar were made in two ways : in the one, the 

 sugar was added to the juice in the usual way (10 per cent.), and 

 water was then added to bring about the desired dilution, the 

 ratio of the sugar to juice being therefore kept constant ; in the 

 other, the dilution was made with a 10 per cent, solution of sugar, so 

 that the ratio of sugar to the total volume was maintained throughout. 

 The results obtained are set out in TaUlc IV. An examination of the 

 results will at once show that the auto-fermentation of the juice is 

 greatly influenced by dilution both with water and with salt solution. 

 The addition of an equal volume of water sensibly retards the action, 



