120           THE MICROTOMIST'S VADE-MECUM
preserve their form   for many hours. He uses a tolerably
concentrated aqueous solution, to which it is frequently advis-
able to add 1 per cent. of acetic acid (glacial) or a trace of
osmic acid (0-1 to 1 per cent.). Washing out is easily done        1
with water.                                                         i'
143. Methyl-Green (for amyloid degeneration) (Gursch-           '"
mann's method').-" A 1 per cent. aqueous solution is used, a       itte
few minutes' immersion being sufficient; a more uniform              P
colouration is produced by using a more dilute solution and
immersing the section for a longer time. Alcohol, turpentine,
and oil of cloves quickly discharge the colour, hence specimens
cannot be mounted in balsam (sic), but may be mounted in           t
glycerin."                                                         TiSue
" Dr. Curschmann, of Hamburg, claims that methyl-green          eld
has a peculiar affinity for amyloid substance, colouring it an     Thest
intense violet; surrounding tissues that have not undergone       sarjbo,
degeneration are stained green or bluish green. The contrast       vided.
is striking; the smallest spot of amyloid disease can be readily
discovered. Methyl-green also colours hyaline casts ultra-         t
marine blue, so in a section of the kidney the healthy tissue       1fl
would appear green, hyaline casts blue, and amyloid spots           I
violet."                                                            5he
144. Piero-Anilin (Tafani's method2).-Tafaniwas led to seek      monsti!
for a green stain, obtained by the combination of anilin-blue      intheel
with picric acid, through observing that blue stains in general    of Pieei
are (optically) unfavorable to definition.    Picric acid was       141
chosen in preference to chromic acid on account of its greater     obtaine
harmlessness to the tissue-elements, whilst anilin-blue was         given
taken as the blue colouring agent on account of its more           I sluiot
selective action on certain tissues (spleen, lymphatic, central     eera
nervous tissues), and its resistance to acids.                      moot
1 'Louisville Medical Herald,' ii (1880), p. 123. 'Journ. Roy. Mic.  1Y1
Soc.,' iii (1880), p. 857.
2 ' Journ. Roy. Mic. Soc.,' i (1878), p. 82. 'Journal de Micro-
graiphie.'


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