Differential Reduction of Methylene Blue by Living Organisms

Abstract

With the oxidized dye and with a leucobase prepared by adding-small amounts of HCl and Na₂S₂O₃ to dye solutions axial differentials or gradients in rate of reduction of dye have been observed in various unicellular and multicellular organisms. Paramecium, is able to reduce methylene blue in mixtures of culture fluid and dye exposed to air, provided the animals are numerous in proportion to volume of fluid or gather in aggregations and decrease oxygen locally, or provided other organisms which take up oxygen are present, but reduces more rapidly in sealed preparations with small amounts of fluid. With high oxygen content of solutions the anterior ectoplasm stains more rapidly than other parts. In low concentrations of dye with somewhat lower oxygen content permitting some reduction stain appears first in the deepest part of the posterior entoplasm, extends anteriorly in the entoplasm and the ectoplasm does not stain or stains more slowly, also from posterior to anterior, except for the extreme posterior tip which often stains less rapidly than adjoining regions. Apparently rate of staining under these conditions varies inversely as reducing power of different regions. In stained but uninjured animals reduction first becomes evident in the ectoplasm of the anterior end and progresses posteriorly, somewhat more rapidly along the peristome than on the aboral side and the extreme posterior tip of some individuals shows early reduction. In high concentrations the anterior ectoplasm stains more rapidly and more deeply than other regions at first and with sufficient staining it is injured and its reducing power is decreased or lost while more posterior regions are still able to reduce the dye in low oxygen.