The Effect of Gentian Violet on Protozoa

In the original communication of Churchman 1 on the selective bactericidal action of gentian violet, published two years ago, the suggestion was made that similar studies should be carried out on the effect of the dye on growing tissue. This communication contains the report s of work undertaken in that direction. The work was primarily undertaken to settle two questions raised by the observations on the effect of gentian violet on bacteria. These two questions were (a) whether the nucleus of a single-celled organism could be stained during life, and (b) whether such a stained organism was capable of further reproduction. 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 the unstained bacteria. The retention of motility by the stained organisms might be explained as a survival phenomenon; and the growth of the 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