By T.J. BURRILL, M.D., Champaign, Ill.
Having had considerable experience in the use of the alcoholic solutions
of aniline dyes for staining bacteria, and having for some months used
solutions in glycerine instead, I have come to much prefer the latter.
Evaporation of the solvent is avoided, and in consequence a freedom
from vexatious precipitations is secured, and more uniform and reliable
results are obtained. There is, moreover, with the alcoholic mixtures a
tendency to "creep," or "run," by which one is liable to have stained
more than he wishes--fingers, instruments, table, etc.
From these things the glycerine mixtures are practically free, and there
are no compensating drawbacks. For staining _Bacillus tuberculosis_ the
following is confidently commended as preferable to the materials and
methods heretofore in use. Take glycerine, 20 parts; fuchsin, 3 parts;
aniline oil, 2 parts; carbolic acid, 2 parts.
The solution is readily and speedily effected, with no danger of
precipitation, and can be kept in stock without risk of deterioration.
When wanted for use, put about two drops into a watch glass (a small
pomatum pot is better) full of water and gently shake or stir. Just
here there is some danger of precipitating the coloring matter, but the
difficulty is easily avoided by gentle instead of vigorous stirring.
After the stain is once dissolved in the water no further trouble
occurs; if any evaporation takes place by being left too long, it is the
water that goes, not the main solvent. The color should now be a light,
translucent red, much too diffuse for writing ink. Put in the smeared
cover glass, after passing it a few times through a flame, and leave it,
at the ordinary temperature of a comfortable room, half an hour. If,
however, quicker results are desired, boil a little water in a test tube
and put in about double the above indicated amount of the glycerine
mixture, letting it run down the side of the tube, gently shake until
absorbed, and pour out the hot liquid into a convenient dish, and at
once put in the cover with sputum. Without further attention to the
temperature the stain will be effected within two minutes; but the
result is not quite so good, especially for permanent mounts, as by the
slower process.
After staining put the cover into nitric (or hydrochloric) acid and
water, one part to four, until decolorized, say one minute; wash in
water and examine, or dry and mount in balsam.
If it is desired to color the ground material, which is not necessary,
put on the decolorized and washed glass a drop of aniline blue in
glycerine; after one minute wash again in water and proceed as before.
Almost any objective, from one-fourth inch up will show the bacilli if
sufficient attention is paid to the illumination.--_Med. Record_.
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