abs.
Aqu. dest.
Glycerine _aa_ 100.0
Glacial acetic acid 10.0
Alum in excess

The fluid must stand for some weeks. The preparations, fixed in absolute
alcohol, or by short heating, stain in from half-an-hour to two hours.
The haemoglobin and eosinophil granules are red, the nuclei stain in the
colour of haematoxylin. The solution must be very carefully washed off.

2. In the practical application of the triacid fluid, particular care
must be taken, as M. Heidenhain first shewed, that the dyes are
=chemically pure=[6]. Formerly granules, apparently basophil, were
frequently observed in the white blood corpuscles, particularly in the
region of the nucleus. They were not recognised, even by practised
observers (_e.g._ Neusser) as artificial, but were regarded as
preformed, and were described as perinuclear forms. Since the employment
of pure dyes these appearances, whose meaning for a long time puzzled
us, are but seldom seen.

Saturated watery solutions of the three dyes are first prepared, and
cleared by standing for some considerable time. The following mixture is
now made:

13-14 c.c. Orange-g. solution
6-7 c.c. Acid fuchsin solution
15 c.c. Aqu. dest.
15 c.c. Alcohol
12.5 c.c. Methyl green
10 c.c. Alcohol
10 c.c. Glycerine

These fluids are measured in the above-mentioned order, with the same
measuring glass; and from the addition of methyl green onwards the fluid
is thoroughly shaken. The solution can be used at once, and keeps
indefinitely. The staining of the blood specimen in triacid requires
only a little fixation, cp. page 35. The stain is completed in five
minutes at most.

The nuclei are greenish, the red blood corpuscles orange, the acidophil
granulation copper red, the neutrophil violet. The mast cells stand out
by "negative staining" as peculiar bright, almost white cells, with
nuclei of a pale green colour.

The triacid stain is very convenient. It is much to be recommended for
good general preparations; =it is indispensable in all cases where the
study of the neutrophil granulations is concerned=.

3. =Basic double staining.= Saturated, watery methyl-green solution is
mixed with alcoholic fuchsin.

The stain, which only requires a small fixation, is completed in a few
minutes, and colours the nuclei green, the red blood corpuscles red, the
protoplasm of the leucocytes fuchsin colour. It is therefo