CYTOLOGICAL METHODS

2. Alum-carmine (Partsch's formula, ' Arch. Mik. Anat.,'
xiv (1877), p. 180).
3. Picro-carmine (often causes swellings, especially when
i not quite neutral).
4. Anilin.
5. Hematoxylin.    (The two last are the most troublesome,
I but give the best results. With huematoxylin it is best to
'use very dilute solutions, and to stain very slowly. For the
nuclei of vegetal cells any of the usual stains may be used
with good results; bmatoxylin is apt to stain too intensely.)
486.1 These processes have since been further worked out,
and Flemming now (1882) adds the following instructions:
All fixing agents alter cell-structures if they are allowed to
act too long; it is always best to examine specimens after not
more than half an hour's immersion.
In opposition to Henle ('Arch. Mik. Anat.,' xx Bd., 4
Heft), Flemming maintains his above-quoted position " that
those who work at nuclear figures with chromic salts are
hopelessly in the wrong road." Chromic salts are excellent
Teagents for general histological work, but not for nuclear
structures. They dissolve nucleoli, destroy nuclear networks,
and swell-up and distort karyokinetic figures to such a degree
that the appearances obtained from them are merely unnatural
caricatures of the true structure.
Chromic acid gives equally good results in all strengths
from ) to -1 per cent.; for certain plant-structures it may be
taken of 1 per cent.
Picric acid may be taken either concentrated or weaker.
Acetic or formic acid should not be stronger than 1 per cent.
Altmann's nitric-acid method (formula No. 28) is excellent
for the purpose of hunting for cell-divisions in tissues; but
the minute structure of the figures is not so well preserved as
it is by means of chromic or picric acid. The same must be
said of Kleinenberg's picro-sulphuric acid method.
1 ' Zellsubstanz, &c.,' p. 379, et seg. et passim.

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