262 Di. A. M.H-f.ulyen, Dr. G. H. Morris, ami Mr. S. i:.,wlaud. 



and, in some cases, di' "> " <lnnlili' /<./ Until// >/'//<.- th<- 



evolution '/'/">. With salt solution, the action is still more marked. 



In the presence of sugar the retarding action is still distinctly 

 apparent, especially when the concentration of the sugar decreases 

 with dilution. In this case the effect of dilution is fully as marked as 

 in the case of water alone or of salt solution. When the strength of 

 the sugar solution is maintained constant, the retardation is still con- 

 siderable, but not so great as in the other cases. 



This paralysing effect of dilution on the activity of the .juice is so 

 contrary to the behaviour of enzymes in general under similar condi- 

 tions, that in our opinion it forms a grave objection to the acceptance 

 of Buchner's enzyme theory. Since the above experiments were 

 made, we find that Wroblewski* has conducted dilution experiments 

 with like results. 



In connection with the question of the influence of dilution on 

 enzyme action, it may be mentioned that when a sample of six-day 

 juice was diluted to 1 in 1000 with cane-sugar solution, 50*5 per cent, 

 of the cane-sugar was found to be inverted, whilst with another juice, 

 three days old, a dilution of 1 in 100 showed an inversion of 79'5 per 

 cent, of the cane-sugar present. This offers a great contrast to the 

 effect of dilution of the juice on the production of carbon dioxide. 



Ratio of Carbon Dioxide to Alcohol. In connection with the question 

 whether we had to do with a true alcoholic fermentation, it became 

 important to determine if carbon dioxide and alcohol were produced 

 in the proportions ordinarily found, and if the amount of sugar which 

 disappeared during the experiment bore any relation to the alcohol 

 and carbon dioxide. We carried out a large number of experiments 

 with a view to elucidate these points, and the results of some of the 

 experiments are shown in Table V. In experiments 1 to 5, the 

 alcohol and carbonic acid estimations were made on the same fermenta- 

 tion, but in experiments 6 to 15 we carried out duplicate fermenta- 

 tions, under identical conditions with the same juice, for the two 

 determinations. We did this in order to ensure greater accuracy in 

 the alcohol estimation, since the escaping gas could le washed by 

 passage through a little water, which was subsequently added to the 

 distillation flask. When we were estimating both products from the 

 same experiment this was not possible. 



It will be noticed from the table that the juice as it comes from the 

 press always contains a considerable amount of alcohol, and we found 

 on examination that this agrees fairly closely with the amount of 

 alcohol contained in the yeast, oven after the thorough washing and 

 pressing to which it had been subjected in the preliminary treatment. 



When corrections are made for the amounts of alcohol and of carbon 

 dioxide formed during the auto-fermentation of the juice, the ratio 

 'Centralbl. f. Physiol.,' 1899, p. 284. 



