The results as to the total fermentations in experiments of this kind are liable to be vitiated by the circumstance that when a low initial concentration of sugar is employed, the supply of sugar may be so greatly exhausted before the close of the experiment as to cause a marked diminution in the rate of fermentation and hence an unduly low total. Even allowing, however, for any effect of this kind, the foregoing table clearly shows the increase in total fermentation and the decrease in initial rate accompanying the increase of sugar concentration from 10 to 40 per cent. Working with a greater range of concentrations (3·3-53·3 grm. per 100 c.c.) Lebedeff has obtained similar results with maceration extract [1911, 4], but has found that the total amount fermented diminishes after a certain optimum concentration (about 33·3 grm. per 100 c.c.) is reached. A practical conclusion from these experiments is that a high [p035] concentration of sugar tends to preserve the enzyme in an active state for a longer time. Simultaneously it prevents the development of bacteria and yeast cells. (/f/) /Effect of Varying Concentration of Yeast-Juice./ This subject, which is of considerable importance with reference to the question of the protoplasmic or enzymic nature of the active agent in yeast-juice, has been examined in some detail by Buchner [Buchner, E. and H., and Hahn, 1903, pp. 158-65] and by Meisenheimer [1903] for juices from bottom yeast, by Harden and Young [1904] for those from top yeast, and by Lebedeff [1911, 4] for maceration extract, the results obtained being in substantial agreement. Dilution of yeast-juice with sugar solution, so that the concentration of the sugar remains constant, produces a small progressive diminution in the total fermentation, which only becomes marked when more than 2 volumes are added, and this independently of the actual concentration of the sugar. Dilution with water produces a somewhat more decided diminution, which, however, does not exceed 50 per cent. of the total for the addition of 3 volumes of water. The effect on maceration extract is somewhat greater but of the same kind. The autofermentation of juice from top yeast is scarcely affected by dilution with 4 volumes of water.