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zr af NUI AURA au 
E with a sharp knife. 
1894.] Mieroscopy. 829 
After the sections are made they are placed in alcohol, which dis- 
solves the anise-oil. 
The sections so obtained may be stained with any of the ordinary 
agents. I used Biondi's fluid a good deal ; itis rapid and differentiates 
well. Perhaps the most generally useful stain is Mayer's carmalum. 
This has all the advantages (and they are many) of alum-carmine, and 
has some additional ones of its own. Thus it is much brighter in tint, 
and so forms a better contrast. "This is of special service when Gram's 
or Weigert's method is used for the detection of microbes, as the blue 
tint of alum-carmine is often objectionable when the microbes are 
stained blue. I commonly use picric acid.as a contrast stain with the 
carmalum. The solution used consists of alcohol seventy parts, satur- 
ated watery solution of picric acid 30 parts, and hydrochloric acid i 
part. I find the results obtained to be much better than those yielded 
by picrocarmine in my hands. The whole process of staining by 
carmalum and picric acid need not take many minutes. If necessary 
a gentle heat may be used to hasten the action. An excellent method 
of staining, in many respects, is that described by Nicolle. It is intro- - 
duced as a method of staining microbes which do not stain by Gram’s 
method. The staining agent is Kiihne’s or Sceffler’s blue. I have 
used, chiefly, Kühne's blue, which acts very rapidly, a few seconds 
being usually enough. It is so very vigorous, that dilution is 
sometimes necessary. The section is then washed in water and treated 
with a 10 per cent. solution of tannic acid. This has the effect of fix- 
ing the blue color in nuclei and microbes, so that subsequent treatment 
with alcohol and oil of cloves will not remove the color. The section 
is taken from the tannin solution, washed in water, dehydrated with 
alcohol, cleared with oil of eloves, washed in xylol, and mounted in 
Canada balsam in the usual way. If a contrast stain he desired, then 
eosin or acid fuchsine may be added to the tannin solution. v 
To summarise the method it may be put as follows: - quels 
1. Select an illustrative part of the fresh tissue, and remove a slice — 
2. Place in absolute aleohol and heat the vessel in » water bath to 
| S about 40? C. for half an hour to an hour. — 
3. Dry the tissue and place on the freezing plate of the microtome 
dn a large drop of anise-oil. fe 
moistened with alcohol while cutting. - : 
5. Place in alcohol to remove aniseoil. — 
6. Float out in water and place on slide for staining. 
4. Freeze and cut sections. The upper surface of the knife may be 
d. Stain by any approved rapid method, and inounk «Joerg 4 dac 
