THE MICROROMIST'S VADE-MECUM

toxylin, or anilin. The best results were obtained with anilin
applied in the manner described by Hermann (in ' Tageblatt
der 48 Versammlung deutscher Naturforscher in Graz,' 187,
No. 4, p. 105, vide post, 'Anilin Stains'). This method has
the advantage of procuring a purely nuclear stain.
113. Gold Chloride (Banvier's method ).-The method of
Lwit has been modified by many workers by omitting the
final treatment with undiluted formic acid, and also in some      are
other details. Ranvier proceeds as follows. Reflecting that
the action of the one-third formic acid in which L6wit placed
his tissues must be hurtful to the finer ramifications of the
nerves, he combines the formic acid with a fixing agent de-       I
signed to antagonise its macerating action, and takes for this
purpose the chloride of gold itself. The tissues are placed in   la
a mixture of chloride of gold and formic acid (4 parts of 1       atel
per cent. gold chloride to 1 part of formic acid) which has       :to
been boiled and allowed to cool.2   They remain in this until
thoroughly impregnated (muscle twenty minutes, epidermis         Of@
two to four hours); the reduction of the gold is effected either
by the action of daylight in acidulated water, or in the dark     110
in dilute formic acid (1 part of the acid to 4 parts of water).
The object of boiling the mixture of gold chloride and         tinco
formic acid is this, that "by boiling in the presence of the      aoln
acid the gold acquires a great tendency to reduction, and for     a
this reason its selective action on nervous tissues is enhanced."  R6k16
114. Gold Chloride and Lemon-juice (REnvier's method 3).       hour""
-Instead of combining the formic acid with gold chloride in       lorit
order to mitigate its action, recourse may be had to a less       Mutl
injurious acid than formic acid. Ranvier finds that of all
acids lemon-juice is the least hurtful to nerve-endings. He
therefore soaks pieces of tissue in fresh lemon-juice filtered
through flannel, until they become transparent (five or ten
I ' Quart. Journ. Mic. Sci.' (N.S.), 1xxx (1880), p. 456.
2 'Trait4,' p. 826.
3 ' Trait6,' p. 813.

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