III. The influence of polarized light on yeast and bacteria

Abstract

In connection with the experiments on the biological effects of polarized light described in the preceding communications, a study was made of the influence of such light on yeast and bacteria. A suspension of ordinary baker's yeast, Saccharomyces cerevisiæ, was made, and equal quantities of such a suspension were added to solutions of sucrose in fermentation tubes. Such tubes were exposed to polarized light, and also to non-polarized light of the same intensity and at the same temperature. It was found that the fermentation of sugar in polarized light proceeded much more rapidly than in non-polarized light as indicated by the amount of carbon dioxide gas evolved in the fermentation tubes. Following the experiments on yeast a number of other experiments were begun on smaller microscopi'c plants, namely bacteria. Cultures of B. coli and B. typhosus were exposed to polarized light, and also to non-polarized light of the same intensity and at the same temperature. While the number of experiments with bacteria so far has not been very great, the results obtained seem to indicate that the bacterial cultures grow more profusely in polarized light. These experiments will be continued on a larger scale but it was deemed advisable to announce the results obtained so far, in view of the most interesting communication published recently by T. F. Morrison of Princeton University, concerning the effect of polarized light on the growth of certain luminous bacteria. This author found that such bacteria flourished better under polarized light. If the above observations should be confirmed by further repeated experiments the results obtained would be of great hygienic interest, showing from a new point of view the importance of out-door sunlight in the treatment of certain infections, as sunlight passing through windows is always more or less polarized.