THREE FIGURES
To avoid coniplications resulting from uncontrolled cell multiplication in the course of experiments with living yeast, various investigators have resorted to measures such as short observation periods, media deficient in sugar or utilizable nitrogenous materials, resting cell suspensions, temperature unfavorable to growth and addition of growth inhibiting agents. I n this paper observations are recorded relevant to the attainment of a constant fermentation rate with a stable yeast population in a medium which, when sufficient oxygen is present, permits yeast growth to the extent of more than 300 million cells per milliliter. Thus, yeast metabolism can be studied in a n excellent nutrient medium with cells which are in a steady state with respect to growth and sugar utilization. Several advantages of this procedure for studies involving yeast metabolism will be pointed out in the discussion.
EXPERIMENTAL PROCEDURE
Ycast strain. A11 experiments were conducted with a distillery type yeast obtained from Joseph E. Seagram & Sons, Inc., Louisville, Kentucky, under the identification, Sacchoromyces cerevisine, strain DCL. This strain is included in the culture collection of the