The Influence of Sodium Chloride on the Growth and Metabolism of Yeast

The effects of the commoner salts on the physiology of the higher animals and plants have been studied by numerous investi-gators. In order to obtain quantitative data workers in the animal field, e.g., Loeb (1906), Lillie (1901), and Moore (1901), have studied normal rhythmical movements such as heart beat, the contractions of Polyorchis or the contractions of the lymph hearts of frogs. This type of research provided the experimental basis for several important conclusions: (a) in low concentrations the common salts exert a favorable and stimulating effect, (b) a toxic effect is exerted in higher concentrations, and (c) the influ-ence of a salt is modified by the presence of other salts in the solution. In the case of higher plants investigators have con-cerned themselves particularly with the influence of salts on the dry weight of the plant. The unicellular organisms provide a means of analyzing some of these effects in greater detail by chemical methods. Already there is a considerable literature dealing with this branch of the field. Several workers have shown recently that low concentra-tions of many different salts stimulate the growth of bacteria. Hotchkiss (1922) in a study of B. coli reported that 15 of a total of 23 chlorides stimulated growth as measured by the turbidity method. This was true of those salts which are usually considered to be particularly toxic. Holm and Sherman (1921) found that 0.2 M concentration of NaCl hastens the appearance of turbidity in media inoculated with B. coli. No measurements were made of total growth. Brooks (1919) made the important observation that an increased output of C02 by B. su.btilis took place in the