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II . — On some Methods for preparing the Tissues of the 
Frog Tadpole's Tail. 
By R. L. Maddox, M.D., Hon. Fel. R.M.S. 
Of the various methods employed by me lately to try and render 
more or less transparent some of the tissues of the common frog 
tadpole’s tail without inducing a too great granularity, and yet give 
distinct views of the relations and paths of the different sets of 
nerves, cutaneous and deeper seated, I beg to offer the following, 
thinking the plans may be of interest to readers of the Journal, and 
believing they embrace some novelty in the treatment. The tissues 
are not stripped, hence the relations are not destroyed; but the 
epidermis is removed so as to permit a clearer view into the thin 
parts of the tail, in fact completely through the textures. It is not 
worth while to do more than briefly recount some of the numerous 
methods, and those which have yielded excellent results, more in 
detail. 
Methods 1, 2, and 3. — After removing the epidermis, as 
described farther on, chloride of gold and chloride of cobalt solutions 
mixed in various strengths and various ways were tried. 
Methods No. 4 and 5. — Chromic acid solution followed by 
tincture of logwood and chloride of zinc solution ; also the chloride 
of zinc replaced by chloride of tin solution (these two reagents 
having been employed by me in 1868, when working on the 
structure of the papillae of the frog’s tongue, and found to beautifully 
stain the nerves of a blue or blue-violet colour) ; and these plans 
used in different ways more or less successfully on the tadpole’s 
tail, but did not equal the methods following. 
No. 6 Plan. — Living specimens, also tadpoles that had been 
dead at least for twelve hours, were placed in chromic acid solution, 
3 drams (strength J per cent.) with 20 drops of spirit of sweet 
nitre, for five minutes or a little longer; then washed in pure water 
thrice, changed for ten minutes ; now immersed in a few drams of 
ammoniated water (strength 4 drops of the strong liquor of 
ammonia to 3 drams of pure water) for about three minutes or 
until the epidermic epithelium was softened into a sort of mucoid 
film, then quickly removed into pure water in a Wedgwood 
evaporating dish, and gently brushed under water with a soft long 
camel-hair pencil ; now rewashed for ten minutes, changing the 
water three or four times, and replaced in fresh chromic acid and 
sweet nitre mixture for twenty minutes ; then rewashed in several 
changes of pure water for ten minutes, and placed in diluted tinc- 
ture of logwood for five minutes (strong tincture diluted with pure 
water until of a golden or sherry colour) ; again well washed and 
