121 
NOTE ON THE STAINING OF BACTERIAL FLAGELLA 
WITH SILVER 
By J. W. W. STEPHENS, M.D., Cantab 
WALTER MYERS LECTURER IN TROPICAL MEDICINE, LIVERPOOL 
IN a short communication to the Lancet, 1898, I stated that by using largin, an 
albuminate of silver, I had easily been able to obtain well-stained and clear 
specimens of flagella. I observed at the time that this body, largin, smelled 
distinctly of ammonia, and I suggested that my success in using this modification of 
Van Ermengem's well-known method was due to this cause. I was unable at the 
time to pursue the matter further, and left it to any other person interested in the 
subject to carry out. So far as I know no one has pursued the subject in this 
direction, and it is only quite recently that 1 have again taken the matter up. 
I will not here give all the many experiments 1 made, suffice it to say that it 
soon became clear that the advantage in using largin depended not upon its albumi- 
nate but upon its ammonia content. 
So that I next experimented with ammoniacal silver solutions, but found that 
it was more convenient to add the ammonia to the tannic and gallic acid solution of 
Van Ermengem, because ammonia precipitates this acid solution, and by dissolving 
the precipitate in excess of ammonia a clear solution is got. With this ammoniacal 
solution I was able to get beautifully stained specimens. 
I next proceeded to find out which constituent of Van Ermengem's somewhat 
complex mixture was the essential one, and 1 found that an ammoniacal solution of 
tannic acid alone gave as good results as Van Ermengem's mixture. (So far as I have 
experimented, gallic acid alone has not given me positive results). It was next a 
question of determining the best proportions of tannic acid and ammonia respectively, 
and after numerous trials I find that good results can be constantly got in the 
following way, though I do not assert that I have yet found the best proportions :— 
1 take no extraordinary precaution in cleaning glass sides — for the whole of 
the staining is most readily done on slides — except that after cleaning with a pocket- 
handerchief I heat the slides thoroughly on a clean piece of wire gauze over the 
bunsen. 
R 
