MICROSCOPICAL EXAMINATION. 205 
maceration of the chromic acid. Even under the best 
conditions it is almost impossible to stain some spores. 
Staining Flagella. For the demonstration of flagella, 
which are possessed by all motile bacteria, we are in- 
debted to Loeffler. The special stains devised by him, 
and also the one devised by Van Ermengem, are those 
usually employed. 
Bunge’s modification of Loeffler’s method is carried 
out as follows: Cover-glasses which have been most 
carefully cleaned are covered by a very thin smear of 
an eighteen-hours’ old culture of the motile organism 
to be examined. After drying in the air and passing 
three times through the flame the smear is treated with 
a mordant solution, which is prepared as follows: To 
3 parts of saturated alum solution add 1 part of a solu- 
tion of liquor ferri sesquichloride, of the strength of 
1:20 of distilled water. To 10 c.c. of this mixture 
add 1 ¢.c. of a concentrated watery solution of fuchsin. 
This mordant should be allowed to stand for several 
days before using. After preparing the cover-slip with 
all precautions necessary to cleanliness the filtered mor- 
dant is allowed to act cold for five minutes, after which 
it is slightly warmed and then washed off. After dry- 
ing the smear is faintly stained with the carbol fuchsin 
solution and then washed off, dried, and mounted. 
Frequently the flagella appear well stained, but often 
the process has to be repeated a number of times before 
success is arrived at. 
The Preservation of Specimens. Dry unstained or 
stained preparations of bacteria keep indefinitely if 
mounted in Canada balsam, cedar oil, or dammar lac; 
they tend to gradually fade, but may be preserved for 
many months or years. 
