Demonstration of bacterial capsules

Abstract

Being the authors interested in a rapid method for the demonstration of bacterial capsules in cultures and considering that the aqueous staining solutions are not satisfactory unless recently prepared; the demonstration of capsules is not a frequent laboratory work, so that the aqueous staining solutions only at times may be recent; the most reliable stains are those of invariable composition; an attempt was made in such a way and, after a series of tests, a new staining technic for the demonstration of capsules in cultures is proposed. It is simple and use is made of an alcoholic solution of crystal violet. As far as the "Aussenhülle" is concerned, it was found to occur, not constantly, in the preparations of Klebsiella pneumoniae under observation. In the course of experiments the authors have noted a marked action of certain chemicals on the capsular swelling; then, they intend to improve the method described in this paper.