Slator2 has shown that the rate of fermentation of dextrose by yeast is proportional to the concentration of the yeast, over a wide range of concentration. The rate is almost independent of the concentration of the sugar, except in very dilute solutions. The diffusion of sugar into the yeast-cell is sufficiently rapid to supply more sugar than can be fermented by the cell, even in dilute solutions.3 Lævulose is fermented at the same rate as dextrose by different yeasts; and maltose at almost the same rate, by those yeasts which contain maltase. Malt wort, during the first part of the fermentation, is also fermented at the same rate as dextrose; the temperature and the concentration of the yeast are the chief factors which determine the rate. Temperature, in fact, has a considerable influence upon the activity of yeast. At 35°, for instance, the quantity of sugar fermented per unit of time in an experiment was nearly double the quantity at 25°, and this again was about six times as much as at 10°.