NERVE-ENDINGS IN MUSCLES

549. Smooth-muscle, Nerve-endings in (Cscheidlen's me-
thods 1).-The following directions are given for the employ-
ment of gold after Lowit's manner :-Place the fresh tissue
(after having rinsed the surface with distilled water) in
formic acid (of from 2 to 4 per cent.) for twenty-four
hours. Thence remove it direct to 1 per cent. gold chloride,
where it remains till it becomes straw colour (which should
be in about fifteen minutes), rinse with water, and bring it
back into the formic-acid solution. Leave it to reduce therein
in the dark for twenty-four hours, wash, and mount in gly-
cerin. Gscheidlen thinks these preparations are permanent;
none of his have faded, but all are as fine as when first
mounted more than two years before.
550. Nerve-endings in Smooth Muscle.2-Ranvier recom-
mends one or the other of his two gold-processes (Nos. 113
and 114). The bladder of frogs should be carefully distended
by injection of the lemon-juice or gold chloride and formic
acid through the cloaca.
551. Innervation of Bladder of Frog (Wolff's qmethods 3
A frog is killed and a solution of gold chloride of 1-20,000
injected into the bladder through the anus. (If the injec-
tion flows out on removal of the syringe, tie the frog's thighs
together.) Now open the frog, dissect away the attachments
of the bladder, ligature the intestine above the bladder, and
cut away the abdomen of the frog so as to have in one piece
bladder, rectum, and hind-legs. (All this time the bladder
must be kept moist with weak gold-solution.) The bladder
and the rest are now put into gold-solution of 1-2000 for
four hours; the bladder is then excised, slit open, and pinned
(with hedgehog spines) on to a cork (outside downwards).
Place it under running water until all the epithelium is
washed away. Use a pencil if necessary. Put for twenty-
' Ibid., xiv (1877), p. 325.
2 ' Traitd,' p. 854.
3 'Arch. Mik. Anat.,' xx (1881), p. 362.

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