. Carnegie Institution of Washington publication. 166 BACTERIA IN RELATION TO PLANT DISEASES. In addition to large quantities of carbon dioxide, ginger beer contains during eaily stages of fermentation traces of alcohol and acetic acid, while relatively large quantities of an acid resembling lactic acid, if not identical with it are formed. Just what each organism gains from the combination was not made out clearly, but the yeast seems to do better in the presence of the bacterium than where separated from it. The following pertinent paragraphs from Ward's paper may close this review: "Ev
. Carnegie Institution of Washington publication. 166 BACTERIA IN RELATION TO PLANT DISEASES. In addition to large quantities of carbon dioxide, ginger beer contains during eaily stages of fermentation traces of alcohol and acetic acid, while relatively large quantities of an acid resembling lactic acid, if not identical with it are formed. Just what each organism gains from the combination was not made out clearly, but the yeast seems to do better in the presence of the bacterium than where separated from it. The following pertinent paragraphs from Ward's paper may close this review: "Everything points to the view that the relations between the yeast and the bacterium are those of true symbiosis, because every attempt to feed the schizomycete with dead yeast-cells or decoctions of such, or detect it embracing such cells in a dead or feeble condition has failed. " It is significant that the synthesis of this dual organsim—which is so strikingly like the lichen that we may compare it forthwith with one of the gelatinous forms—was most easily brought about by adding the yeast-cells to already advanced cultures of the bacterium, both having been grown in the same medium and under like conditions. * * * "The schizomycete is favored by obtaining some substance or substances directly they leave the sphere of metabolic activity of the yeast-cells; it can benefit by the presence of these substances, even apart from the living yeast, though to a less extent. "The yeast,on the other hand, benefits by these substances being removed and destroyed, hence its renewed and continued activity—as evidenced by the steady and copious evolution of carbon- dioxide for weeks, and the corresponding increase of the yeast-cells by budding—when the symbiosis is established. "For the present this can only be regarded as a hypothesis. It might be objected that I have inverted the order of things—that, since the schizomycete is able to evolve small quantities o
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