The effect of gentian violet on protozoa and on growing adult tissue

Abstract

This study was primarily undertaken to settle two questions raised by the observations made during the last two years on the effect of gentian violet on bacteria. 1 It was noticed early in the gentian violet studies that motile organisms not killed by the stain (violet negative organisms) retained their motility even though deeply stained; and that these stained violet negative organisms when transplanted to agar slants grew equally well with the control smears of unstained bacteria. The retention of motility by the stained organisms might in these experiments be explained as a survival phenomenon; and the growth of transplants made from the stained specimens might be regarded as arising, not from the organisms in the smear which had taken the stain, but from the few in the smear which had escaped it. It seemed altogether likely, from other observations that these explanations were not the correct ones; and that the violet negative organisms actually took the stain during life. Still, definite proof was lacking that gentian violet in these experiments was acting as a true intra-vital stain. To furnish this proof and to investigate the further problem (raised but not solved by the experiments with bacteria) as to whether the vital dye stained the nucleus or the protoplasm, two series of experiments have been done; one with a protozoon (paramecium) and another with living tissues.